Abstract:
A heat exchanger ( 1 ), an energy recycling system, a fluid distribution manifold and a baffle. The heat exchanger comprising: a first fluid tube ( 25 ) through which a first fluid of a first temperature flows; a second fluid tubes ( 26 ) through which a second fluid of a second temperature flows; a baffle ( 22 ) located in at least one of said tubes for moderating flow of at least one fluid passing therethrough; wherein the heat exchanger ( 1 ) is configured for communicating thermal energy between the first fluid and the second fluid.

Description:
FIELD OF INVENTION 
       [0001]    The present invention relates to heat exchanging technology. In particular, the present invention relates to a heat exchanger, an energy recycling system, a fluid distribution manifold and a baffle. 
       BACKGROUND OF THE INVENTION 
       [0002]    In everyday life, people may use different washing facilities for cleaning and washing. These facilities include, for example, bathroom showers, sinks, washing tanks and the like. However, if the washing facilities use hot water as a washing medium, such wastewater discharged by the facilities still contains a huge amount of heat, thereby resulting in a waste of energy. 
         [0003]    All along, people have tried various methods to recover and utilize the energy lost in vain. For example, U.S. Pat. No. 4,619,311 discloses an “equal volume, contra flow heat exchanger”, which provides a heat exchanger and an energy recovery device for improving heat energy recovery from hot wastewater. As shown in  FIGS. 1 and 1A , a heat exchanger  430  includes an inner wastewater pipe  410  made of copper or aluminum with smooth inner walls and an outer pipe  412 , the heat exchanger  430  is installed vertically, and the inner wastewater pipe  410  is connected to a drain pipe  429  of a bathtub or sink  460  or the like, so that hot wastewater  432  passes through the inner wastewater pipe  410  from the top down and drains into sewers, cold feed water  426  enters the heat exchanger  430  from a water inlet  417  through a cold water pipe  416  and flows out from a water outlet  419  as preheated water, and the preheated water flows into a water heater  420  through a pipeline  418  to be further heated for application or storage. As shown in  FIG. 1A , the cold feed water  426  passes between the inner wastewater pipe  410  and the outer pipe  412  from the bottom up and forms a “cold water jacket” surrounding the inner wastewater pipe  410 , and the cold feed water exchanges heat with hot wastewater reversely flowing in the inner wastewater pipe  410 . As the inner diameter of the inner wastewater pipe  410  is greater than that of the drain pipe  429 , the hot wastewater will not fill the cavity of the whole inner wastewater pipe  410  when passing through the inner wastewater pipe  410 , which can be attached to the inner wall of the inner wastewater pipe  410  to form a thin film of the hot wastewater  432  to flow downwards spirally. The preheated water flowing out from the water outlet  419  may simultaneously flow into a mixing valve  434  through a pipeline  427 , is mixed into tepid water with hot water from the water heater  420  through a pipeline  444 , and flows out from a sprinkler  346  or a water tap  452  for use. 
         [0004]    Although the heat exchanger and the energy recovery device have a simple structure and can reduce the amount of hot water use and heating energy consumption, the problem of low heat recovery efficiency still exists. As the “cold water jacket”  426  exchanges heat with the hot wastewater through a pipe wall of the inner wastewater pipe  410 , due to resistance of the pipe wall, most of the cold water may quickly pass through a central portion between the inner wastewater pipe  410  and the outer pipe  412  at a higher speed without being fully heated, and with a laminar flow phenomenon of water flow, the cold water quickly passed through is not fully mixed with preheated water that has been heated adjacent to the pipe wall of the inner wastewater pipe  410 , which causes low recovery efficiency. 
         [0005]    The U.S. Pat. No. 4,619,311 is incorporated into the present invention by reference. 
       OBJECT OF THE INVENTION 
       [0006]    Accordingly, it is an object of the present invention to overcome or at least partially alleviate at least some of the deficiencies associated with the prior art. 
       SUMMARY OF THE INVENTION 
       [0007]    Broadly speaking, the present invention has described a fluid heat exchanger and an energy recovery device with high energy recovery efficiency, are simple to install, convenient to use and easy to clean. 
         [0008]    According to a first broad form of the present invention, there is provided a heat exchanger comprising a first fluid tube through which a first fluid of a first temperature flows, a second fluid tube through which a second fluid of a second temperature flows, a baffle located in at least one of said tubes for moderating flow of at least one fluid passing therethrough, wherein the heat exchanger is configured for communicating thermal energy between the first fluid and the second fluid. 
         [0009]    Preferably, the baffle may be configured to exchange thermal energy between the first and second fluid. 
         [0010]    Advantageously, the first tube and second tube may be configured for exchange of thermal energy between the first and second fluid. 
         [0011]    Preferably, the heat exchanger may further comprises a passage between the first fluid tube and the second fluid tube, the passage for receiving fluid leaking from the first fluid tube or the second fluid tube. 
         [0012]    Advantageously, the baffle may be configured for moderating the flow of fluid through at least one of the fluid tubes, according to any one or more of the following configurations: at least one elongate member extending in a direction of radially or along at least one of the fluid tubes; at least one protrusion extending radially from a wall of at least one of the fluid tubes, wherein the protrusion is integrally formed or detachably mounted on the wall; at least one protrusion extending in a direction of along a wall of at least one of the fluid tubes, the protrusion being integrally formed or detachably mounted on the wall; at least one spiral guiding structure extending along at least one of the fluid tubes; and at least one sleeve extending along at least one of the tubes. 
         [0013]    Preferably, the baffle may comprises at least one elongate member extending in a spiral arrangement, wherein the at least one elongate member extends in the direction of around or about at least one of the fluid tubes, or along the direction of the longitudinal axis of at least one of the fluid tubes. 
         [0014]    Preferably, the baffle may comprises at least one elongate member, formed in one or more spiral elements which extend around the inner circumference of the fluid tubes or along the longitudinal axis of the fluid tubes for moderating the flow of fluid through at least one of the fluid tubes, and wherein the at least one elongate member extends in the direction of around or about at least one of the fluid tubes, or extends along the direction of the longitudinal axis of at least one of the fluid tubes. 
         [0015]    Preferably, the at least one elongate member may extend about a core in an interengaged spiral arrangement, in a longitudinal direction along at least one of the fluid tubes. 
         [0016]    Preferably, the baffle may comprises at least one elongate member extending in a direction of around or about at least one of the fluid tubes, or along the direction of the longitudinal axis of at least one of the fluid tubes, and said at least one elongate member includes annular or spiral protrusions thereon. 
         [0017]    Preferably, the baffle may includes at least one protrusion extending radially from a wall of at least one of the fluid tubes and wherein the at least one protrusion extends in a annular or spiral arrangement. 
         [0018]    Preferably, the protrusions may extend in an annular or spiral arrangement along, about or within either or both of the fluid tubes. 
         [0019]    Preferably, the protrusions may extend in a spiral arrangement include a plurality of spaces therebetween, the spaces being substantially aligned to create a turbulent flow with the spiral flow. 
         [0020]    Advantageously, the heat exchanger may further comprises a plurality of elongate members having circumferential helical grooves formed therein, and both the elongate members and the grooves extend in a direction of along at least one of the fluid tubes. 
         [0021]    Preferably, the baffle may includes at least one spiral guiding structure extending along at least one of the fluid tubes, the spiral guiding structure formed by a plurality of members together define a spiral flow path. 
         [0022]    Preferably, the spiral guiding structure may include a plurality of elements formed therein substantially aligned to create a turbulent flow with the spiral flow path. 
         [0023]    Preferably, the baffle may includes a sleeve which extends along at least one of the fluid tubes. 
         [0024]    Preferably, the sleeve may extend along, about or within either or both of the fluid tubes and includes a plurality of holes therein. 
         [0025]    Preferably, the sleeve may extend in interengaged spiral arrangements with a plurality of elongate members. 
         [0026]    Preferably, the baffle may include at least a first and a further layer of elongate members, each of the layers comprising a plurality of elongate members each extending in a common direction, the common direction of the elongate members of the first layer being different from the common direction of the elongate members of the further layer  20 . A heat exchanger according to claim  19 , wherein the elongate members of the first layer are configured so as to be in thermal communication with the wall of at least one of the fluid tubes. 
         [0027]    Advantageously, the baffle may include a sleeve, extending along at least one of the fluid tubes and located between the first layer and the further layer. 
         [0028]    Advantageously, the sleeve may include a plurality of holes therein. 
         [0029]    Advantageously, at least one fluid tube may include a plurality of elongate members wrapped about a common longitudinal axis and along the at least one fluid tube, wherein the fluid tube has generally elliptical cross sectional profile formed by compression of a fluid tube having a generally circular cross sectional profile. 
         [0030]    Advantageously, the baffle may include at least one disc disposed within at least one of the tubes and wherein the disc includes protrusions thereon which define a plurality of flow paths. 
         [0031]    Advantageously, at least one of the fluid tubes of the heat exchanger may be configured for receiving a cleaning tube through an opening formed therein, the cleaning tube directing a fluid stream for displacing deposits formed within the heat exchanger. 
         [0032]    Advantageously, a fluid distribution manifold may have at least one protrusion which is located proximate the inlet of at least one fluid tube of a corresponding heat exchanger, wherein the fluid distribution manifold further includes a vent therein. 
         [0033]    Advantageously, the manifold may distribute fluid into fluid tubes of the heat exchanger via at least one or more passageways defined by the protrusion and manifold, wherein the vent is in communication with at least one of the protrusions. 
         [0034]    Optionally, the air flow to the fluid may be spaced tube apart from the fluid flow by the vent. 
         [0035]    Optionally, the protrusions of the manifold may be spaced apart from the inlet of at least one or more of the fluid tubes so as to direct the flow of air and fluid into the fluid tubes. 
         [0036]    Optionally, the protrusions of the manifold may contact at least a portion of the inlet of at least one or more of the fluid tubes. 
         [0037]    According to a second broad form of the present invention, there is provided an energy recycling system including a heat exchanger and a fluid distribution manifold. 
         [0038]    Preferably, the baffle may be according to any baffle in the embodiment of the heat exchanger above. 
         [0039]    According to a third broad form of the present invention, there is provided a kit for a heat exchanger including a first fluid tube through which a first fluid of a first temperature flows, a second fluid tube through which a second fluid of a second temperature flows, and a baffle for moderating the flow of fluid through at least one of the fluid tubes according to any embodiment of the heat exchanger above. 
         [0040]    According to a fourth broad form of the present invention, there is provided a kit for a heat exchanger according to any embodiment above, and further including a cleaning tube according to any embodiment above, and/or a fluid distribution manifold according to any embodiment above. 
         [0041]    In a further aspect of an embodiment of the present invention, there may be provided a kit for a heat exchanger including a first fluid tube through which a first fluid of a first temperature flows, a second fluid tube through which a second fluid of a second temperature flows, and a baffle for providing resistance to the flow of fluid through at least one of the fluid tubes according to the above. 
         [0042]    In a further embodiment of the present invention there is provided a fluid heat exchanger, including: a first fluid collector having an opening, a cavity and a plurality of first fluid outlets, where the opening covers all the first fluid outlets, for introducing a first fluid into the cavity, and then exporting the first fluid out of the first fluid outlets in parallel; a housing having a second fluid inlet, a second fluid outlet and a second fluid cavity between the second fluid inlet and the second fluid outlet; and a plurality of metal pipes each placed in the second fluid cavity, and forming a plurality of first fluid channels through the second fluid cavity and the housing for the first fluid to pass through in parallel, the first fluid channels separately communicate with the first fluid outlets of the first fluid collector to receive the first fluid exported from the first fluid outlets, where the second fluid inlet is used for introducing a second fluid with a temperature different from that of the first fluid, which flows through the second fluid cavity, and exchanges heat with the first fluid passing through in parallel within the first fluid channels by means of the plurality of metal pipes to change the temperature of the second fluid and then exported from the second fluid outlet. 
         [0043]    In a further embodiment of the present invention there is provided an energy recovery device, which includes the heat exchanger described above and an external means for changing the temperature of the second fluid discharged from the second fluid outlet to an appropriate temperature of use and making the second fluid serve as the first fluid entered the opening of the first fluid collector of the heat exchanger after use. 
         [0044]    The heat exchanger, the energy recovery device and the energy recovery system according to the present invention can efficiently recover energy in fluids, are simple to install, convenient to use and easy to clean, which are suitable for use in showers or sinks or other facilities. 
         [0045]    According to an illustrative embodiment of the present disclosure, a thermal conductive baffle disposed in a fluid channel, wherein the fluid channel is an annular channel formed by internal and external tubular surfaces mutually nested, at least one part of the two tubular surfaces is formed by metal, the baffle clings to the two tubular surfaces and maintains good thermal contact with the metal part of the tubular surfaces, fluids passing through the annular channel exchange heat with substances outside the annular channel by means of the baffle and the metal part of the tubular surfaces, the baffle is formed by one or more metal strips having protruding solid structures, and the centerline of the metal strip is configured to surround the internal tubular surface. 
         [0046]    Optionally, a plurality of annular projections is spaced apart along a length direction of a surface of the metal strip. 
         [0047]    Optionally, the metal strip is spiral spring-like. 
         [0048]    Optionally, a spiral center of the spiral spring-like metal strip has another metal strip. 
         [0049]    Optionally, the metal strip is formed by intertwining of a plurality of metal wires. 
         [0050]    Optionally, the metal strip is a spiral strip having a non-circular cross-section. 
         [0051]    Optionally, the centerline of the metal strip is parallel to the centerline of the internal tubular surface. 
         [0052]    Optionally, the centerline of the metal strip spirally extends around the centerline of the internal tubular surface. 
         [0053]    Optionally, the centerline of the metal strip vertically surrounds the centerline of the internal tubular surface. 
         [0054]    According to another illustrative embodiment of the present disclosure, a baffle having a thermal conductive baffle disposed in a fluid channel, wherein the fluid channel is an annular channel formed by internal and external tubular surfaces mutually nested, at least one part of the two tubular surfaces is formed by metal, the baffle clings to the two tubular surfaces and maintains good thermal contact with the metal part of the tubular surfaces, fluids passing through the annular channel exchange heat with substances outside the annular channel by means of the baffle and the metal part of the tubular surfaces, the baffle comprises a barrel structure made of metal sheets and having a plurality of spiral pits on a surface, and the pits form, in the annular channel, a plurality of spiral channels surrounding the internal tubular surface to allow the fluids to pass in parallel. 
         [0055]    Optionally, the spiral channels leave a straight-through channel therebetween to allow part of the fluids to directly pass through adjacent spiral channels, to increase turbulence effects. 
         [0056]    According to another illustrative embodiment of the present disclosure, a baffle having a thermal conductive baffle disposed in a fluid channel, wherein the fluid channel is an annular channel formed by internal and external tubular surfaces mutually nested, at least one part of the two tubular surfaces is formed by metal, the baffle clings to the two tubular surfaces and maintains good thermal contact with the metal part of the tubular surfaces, fluids passing through the annular channel exchange heat with substances outside the annular channel by means of the baffle and the metal part of the tubular surfaces, and the baffle comprises two layers of metal wires surrounding the internal tubular surface, wherein each layer of metal wires comprises a plurality of metal wire sections with gaps therebetween and arranged in parallel, and at least part of the wire sections in the two layers of metal wires are not parallel to each other. 
         [0057]    According to another illustrative embodiment of the present disclosure, a baffle having a thermal conductive baffle disposed in a fluid channel, wherein the fluid channel is an annular channel formed by internal and external tubular surfaces mutually nested, at least one part of the two tubular surfaces is formed by metal, the baffle clings to the two tubular surfaces and maintains good thermal contact with the metal part of the tubular surfaces, fluids passing through the annular channel exchange heat with substances outside the annular channel by means of the baffle and the metal part of the tubular surfaces, the baffle is formed by a plurality of sheet-like objects superposed in the fluid channel with gaps, the plurality of sheet-like objects each has an opening that allows the fluids to pass, at least one part of the sheet-like objects are spoilers, whose opening is configured such that the fluids passing through the fluid channel need to circuitously pass between the spoilers, and at least one part of the sheet-like object is made of metal and thermally contacts the metal part of the tubular surfaces. 
         [0058]    Optionally, openings of any two closest spoilers do not overlap each other in a main surface direction and are separately adjacent to the internal and external tubular surfaces forming the annular channel. 
         [0059]    According to another illustrative embodiment of the present disclosure, a baffle having a thermal conductive baffle disposed in a fluid channel, wherein the fluid channel is an annular channel formed by internal and external tubular surfaces mutually nested, at least one part of the two tubular surfaces is formed by metal, the baffle clings to the two tubular surfaces and maintains good thermal contact with the metal part of the tubular surfaces, fluids passing through the annular channel exchange heat with substances outside the annular channel by means of the baffle and the metal part of the tubular surfaces, the baffle has a barrel structure made of metal to partition the annular channel into internal and external annular channels mutually nested, and solid baffle structures are formed in the two annular channels separately, and separately thermally contact the barrel structure and the metal part of the two tubular surfaces. 
         [0060]    Optionally, the solid baffle structures form, in the annular channels, a plurality of spiral channels that allows the fluids to pass in parallel. 
         [0061]    Optionally, a straight-through channel is disposed between the spiral channels to allow part of the fluids to pass through adjacent spiral channels by means of the straight-through channel, to increase turbulence effects. 
         [0062]    Optionally, the barrel structure is porous. 
         [0063]    Optionally, the internal and external annular channels have the baffle according to the present invention. 
         [0064]    According to another illustrative embodiment of the present disclosure, a baffle having a thermal conductive baffle disposed in a fluid channel, wherein the fluid channel is formed between two parallel sheet-like objects and a plurality of metal pipes passing through the two sheet-like objects, the two sheet-like objects tightly nest the plurality of metal pipes, the baffle comprises a plurality of first metal wires parallel to each other and a plurality of second metal wires parallel to each other, which are superposed not in parallel to each other to form a metal net, the metal net has a plurality of through holes corresponding to the plurality of metal pipes so as to tightly nest and thermally contact the plurality of metal pipes, and fluids passing through the fluid channel pass through gaps between the two layers of metal wires and the plurality of metal pipes in disorder and exchange heat with substances in the plurality of metal pipes by means of the net-like baffle and the plurality of metal pipes. 
         [0065]    According to another illustrative embodiment of the present disclosure, a baffle having a thermal conductive baffle disposed in a fluid channel, wherein the fluid channel is formed jointly by an inner wall of a pipeline and outer walls of a plurality of metal pipes disposed in the pipeline and parallel to the centerline of the pipeline, the baffle is formed by parallel superposition of a plurality of sheet-like objects whose surface is provided with a plurality of grooves, the sheet-like objects have a plurality of through holes corresponding to the plurality of metal pipes so as to tightly nest the plurality of metal pipes, grooves on surfaces of two adjacent sheet-like objects are not parallel to each other, the plurality of sheet-like objects each has an opening that allows fluids to pass, at least one part of the sheet-like objects are spoilers, configured such that openings of any two closest spoilers do not overlap each other in a main surface direction, so that the fluids passing through the fluid channel need to circuitously pass between the spoilers, at least one part of the sheet-like objects is made of metal and thermally contacts the plurality of metal pipes, and the fluids pass between the grooves in disorder when passing through the fluid channel, and exchange heat with substances in the metal pipes by means of the metallic sheet-like object and the plurality of metal pipes in thermal contact therewith. 
         [0066]    According to another illustrative embodiment of the present disclosure, a baffle having a thermal conductive baffle disposed in a fluid channel, wherein the fluid channel is formed jointly by an inner wall of a pipeline and outer walls of a plurality of metal pipes disposed in the pipeline and parallel to the centerline of the pipeline, the baffle is formed by superposition of a plurality of net-like spoilers, each of the net-like spoilers comprises a plurality of first metal wires parallel to each other and a plurality of second metal wires parallel to each other, the first metal wires and the second metal wires are not in parallel to each other and the first metal wires are superposed on the second metal wires, and each of the net-like spoilers has a plurality of through holes corresponding to the metal pipes so as to nest and thermally contact the metal pipes, and fluids pass between the first and second metal wires in turbulence, and exchange heat with substances in the metal pipes by means of the baffle and the metal pipes. 
         [0067]    Optionally, the net-like spoilers are constructed to form rings having substantially the same width with the through holes as centers, the rings are connected with each other, and except the part of rings, other parts of the net-like spoilers form gaps. 
         [0068]    Optionally, the net-like spoilers are constructed to form rings having substantially the same width with the through holes as centers, the rings are connected with each other, and except the part of rings, the first metal wires and the second metal wires in other parts of the net-like spoilers are flattened to close meshes therebetween. 
         [0069]    According to another illustrative embodiment of the present disclosure, a thermal conductive baffle disposed in a fluid channel, wherein the fluid channel has two parallel surfaces, at least one part of the two parallel surfaces is made of metal, the baffle is formed by at least two layers of non-parallel metal wires, which separately form two parallel surfaces of the fluid channel through contact and thermally contact the metal part, and fluids passing through the fluid channel pass between the metal wires, and exchange heat with substances outside the channel through the metal wires and the metal part forming the channel. 
         [0070]    Optionally, each layer of metal wires comprises a plurality of metal wire sections parallel to each other. 
         [0071]    Optionally, part of metal wire sections of at least two layers of metal wires of the multiple layers of metal wires are formed by the same metal wire and are connected through at least one bend. 
         [0072]    Optionally, the baffle is formed through the following process: a. disposing one or more spiral spring-like metal wires in a circular metal pipe with gaps; and b. flattening the circular metal pipe to form two parallel surfaces, and making the two parallel surfaces press against the plurality of metal wires. 
         [0073]    Optionally, the baffle comprises four layers of metal wires. 
         [0074]    Optionally, the baffle is formed through the following process: a. curling a metal net formed by two layers of non-parallel metal wires into a cylindrical shape to be placed in a circular metal pipe; and b. flattening the circular metal pipe to form two parallel surfaces, and making the two parallel surfaces press against the layers of metal wires forming the net-like cylinder. 
         [0075]    According to another illustrative embodiment of the present disclosure, a fluid heat exchanger, comprising: a metal pipe, in which a first fluid channel that allows a first fluid to pass is formed; and a second fluid channel surrounding the metal pipe, wherein a metal protruding spiral baffle structure in good thermal contact with the metal pipe is formed on an inner wall of the metal pipe; in use, the metal pipe is basically arranged vertically, and the first fluid passing therein does not fill a cavity of the metal pipe, is attached to the inner wall of the metal pipe, is spirally downward along the baffle structure, and exchanges heat with a second fluid passing from the bottom up in the second fluid channel through the metal pipe and the protruding metal spiral structure. 
         [0076]    Optionally, the spiral baffle structure has a plurality of open ends. 
         [0077]    Optionally, open ends of the spiral baffle structure are covered or form a slope to reduce accumulation of fouling at the open ends. 
         [0078]    Optionally, the second fluid channel is an annular channel jointly formed by an inner wall of a second fluid pipeline and an outer wall of a metal pipe disposed in the second fluid pipeline. 
         [0079]    Optionally, the annular channel has a metal baffle thermally contacting the metal pipe, and a second fluid passing through the annular channel exchanges heat with the first fluid passing through the metal pipe through the baffle and the metal pipe in thermal contact therewith. 
         [0080]    Optionally, the annular channel has the baffle according the present invention. 
         [0081]    Optionally, the second fluid channel is formed by one or more flat metal pipes having two parallel surfaces, the flat metal pipe spirally and tightly nests the metal pipe, and one of the parallel surfaces clings to an outer wall of the metal pipe. 
         [0082]    Optionally, the flat metal pipe has the baffle according to the present invention. 
         [0083]    According to another illustrative embodiment of the present disclosure, a fluid heat exchanger, comprising: a first fluid collector having an opening, a cavity and a plurality of first fluid outlets, wherein the opening covers all the first fluid outlets, and a first fluid is collected and introduced to the cavity, and then is exported out of the first fluid outlets in parallel; a housing having a second fluid inlet, a second fluid outlet and a second fluid cavity between the second fluid inlet and the second fluid outlet; and a plurality of metal pipes each placed in the second fluid cavity, and forming a plurality of first fluid channels passing through the second fluid cavity and the housing to allow the first fluid to pass in parallel, the first fluid channels separately communicating with the first fluid outlets of the first fluid collector to receive the first fluid exported from the first fluid outlets, wherein the second fluid cavity has a metal baffle thermally contacting the plurality of metal pipes; and the second fluid inlet is used for introducing a second fluid whose temperature is different from that of the first fluid, which passes through the second fluid cavity, and exchanges heat with the first fluid passing in parallel in the first fluid channels by means of the plurality of metal pipes and the metal baffle, so that the temperature of the second fluid is changed and then the second fluid is exported from the second fluid outlet. 
         [0084]    Optionally, the opening of the first fluid collector is used for introducing the first fluid into the cavity of the first fluid collector. 
         [0085]    Optionally, the metal pipes are formed by mutual nesting of internal and external metal pipes, the internal and external metal pipes maintain good thermal contact therebetween and are provided with a micro-channel that allows the first or second fluid to pass when the internal or external metal pipe breaks. 
         [0086]    Optionally, the micro-channel is communicated to the outlet above the plurality of metal pipes. 
         [0087]    Optionally, the flow divider comprises a plurality of baffles for evenly introducing the first fluid into the plurality of first fluid channels. 
         [0088]    Optionally, the flow divider is detachably installed to the opening of the first fluid collector. 
         [0089]    Optionally, the first fluid is a liquid, the baffles are disposed adjacent to the first fluid outlet and are provided with through holes, and each through hole communicates with an air vent disposed in a higher position. 
         [0090]    Optionally, the through hole is communicated to the air vent through a vent pipe and the collector is further provided with a filtration device which has a through hole nested to the vent pipe. 
         [0091]    Optionally, the baffles are spiral members disposed in the first fluid channel, which facilitate the first fluid to spirally pass in the first fluid channel. 
         [0092]    Optionally, the baffles are detachable. 
         [0093]    Optionally, inner walls of the metal pipes are provided with spiral protruding metal baffle structures in thermal contact with the metal pipes. 
         [0094]    Optionally, upstream open ends of the spiral baffle structure are covered or form a slope to reduce accumulation of fouling at the open ends. 
         [0095]    Optionally, a plurality of second fluid annular channels separately surrounding each metal pipe to allow the second fluid to pass in parallel is formed in the second fluid cavity and the second fluid channel has the metal baffle according to the present invention, which thermally contacts the metal pipes. 
         [0096]    Optionally, the second fluid cavity has a baffle formed by parallel superposition of a plurality of sheet-like objects with gaps, each of the sheet-like objects has a plurality of through holes corresponding to the metal pipes so as to nest the metal pipes, at least one part of the sheet-like objects is made of metal and thermally contacts the metal pipes, at least one part of the sheet-like objects are spoilers, on which an opening that allows the second fluid to pass is formed, and openings of any two closest spoilers do not overlap each other in a main surface direction of the spoilers, to facilitate the second fluid to circuitously pass between the spoilers in the second fluid cavity, and to exchange heat with the first fluid in the metal pipes by means of the baffle and the metal pipes. 
         [0097]    Optionally, the sheet-like objects have the baffle according to the present invention therebetween, which thermally contacts the plurality of metal pipes. 
         [0098]    Optionally, the second fluid cavity has the baffle according to the present invention. 
         [0099]    Optionally, the first fluid is a liquid, and centerlines of the plurality of metal pipes are basically arranged horizontally. 
         [0100]    Optionally, a section of an inner wall of the metal pipes is flat and has a major axis and a minor axis, and the major axis is basically arranged horizontally. 
         [0101]    Optionally, the inner wall of the metal pipes has two parallel surfaces and the two parallel surfaces have the baffle according to the present invention therebetween. 
         [0102]    Optionally, a vertical height of the inner wall of the metal pipes is not more than 6.5 mm. 
         [0103]    According to another illustrative embodiment of the present disclosure, an energy recovery device, comprising: the heat exchanger according to the present invention; and an external temperature-varying apparatus, wherein the second fluid after heat exchange in the heat exchanger is introduced into the external temperature-varying apparatus, the temperature of the second fluid is changed to a suitable operating temperature, and the second fluid, after use, serves as the first fluid introduced into the heat exchanger. 
         [0104]    Optionally, the external temperature-varying apparatus comprises a heater or a cooler. 
         [0105]    Optionally, the external temperature-varying apparatus comprises a fluid mixer mixing the second fluid after heat exchange with an external preheated or precooled third fluid to change the temperature. 
         [0106]    Optionally, the first fluid is wastewater, and the second fluid is clean water. 
         [0107]    Optionally, the heat exchanger is installed to the bottom of a bathtub or a sink of a washing facility or a base of a shower, or is integrally formed with the base of the shower or the sink, to receive hot wastewater generated in shower or washing. 
         [0108]    Optionally, a drain hole of the bathtub, the sink of the washing facility, or the shower covers all first fluid outlets in a horizontal direction. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0109]    The basic structure of the present invention is illustrated below with reference to the accompanying drawings, where: 
           [0110]      FIG. 1  is a schematic structural view of an equal volume, contraflow heat exchanger and an energy recovery device in the prior art; 
           [0111]      FIG. 1A  is a sectional view along Line  1 A- 1 A in  FIG. 1 , illustrating a cross-sectional structure of the heat exchanger in the prior art; 
           [0112]      FIG. 2  is an exploded perspective view of a first embodiment of a fluid heat exchanger according to the present invention, illustrating a schematic structural view of a first embodiment of a baffle according to the present invention; 
           [0113]      FIG. 2A  is a schematic view showing that a protruding spiral structure in a wastewater channel covered by a ring according to a first embodiment of the present invention; 
           [0114]      FIG. 3  is a sectional perspective view of the main body of the fluid heat exchanger shown in  FIG. 2 ; 
           [0115]      FIG. 4  is a sectional perspective view of an assembling state of the fluid heat exchanger shown in  FIG. 2 ; 
           [0116]      FIG. 5  is a schematic view of a metal strip in the first embodiment of the baffle according to the present invention; 
           [0117]      FIG. 6  is a perspective view of a second embodiment of the baffle according to the present invention; 
           [0118]      FIGS. 7-9  are schematic views of a third embodiment of the baffle according to the present invention; 
           [0119]      FIG. 10  is a perspective view of a fourth embodiment of the baffle according to the present invention; 
           [0120]      FIG. 11  is a schematic view of a spiral spring-like metal strip in the fourth embodiment of the baffle according to the present invention; 
           [0121]      FIG. 12  is a perspective view of a fifth embodiment of the baffle according to the present invention; 
           [0122]      FIG. 13  is a perspective view of a sixth embodiment of the baffle according to the present invention; 
           [0123]      FIG. 14  is a schematic view of spiral spring-like metal strips in the sixth embodiment of the baffle according to the present invention; 
           [0124]      FIG. 15  is a perspective view of a seventh embodiment of the baffle according to the present invention; 
           [0125]      FIG. 16  is a schematic view of metal strips of metal wires in the seventh embodiment of the baffle according to the present invention; 
           [0126]      FIG. 17  is a perspective view of an eighth embodiment of the baffle according to the present invention; 
           [0127]      FIG. 18  is a schematic view of a metal spiral strip in the eighth embodiment of the baffle according to the present invention; 
           [0128]      FIG. 19  is a perspective view of a ninth embodiment of the baffle according to the present invention; 
           [0129]      FIG. 20  is an exploded perspective view of the ninth embodiment of the baffle according to the present invention; 
           [0130]      FIG. 21  is a perspective view showing that the baffle shown in  FIG. 19  is installed in the heat exchanger; 
           [0131]      FIG. 22  is a perspective view of a tenth embodiment of the baffle according to the present invention; 
           [0132]      FIG. 23  is a perspective view showing that the baffle shown in  FIG. 22  is installed in the heat exchanger; 
           [0133]      FIGS. 24-25  are schematic views of an eleventh embodiment of the baffle according to the present invention; 
           [0134]      FIG. 26  is a schematic view of a twelfth embodiment of the baffle according to the present invention; 
           [0135]      FIG. 27  is a perspective view of a metal strip for manufacturing the baffle shown in  FIG. 26 ; 
           [0136]      FIG. 28  is a perspective view showing that the baffle shown in  FIG. 26  installed in the heat exchanger; 
           [0137]      FIG. 29  is a schematic view of a thirteenth embodiment of the baffle according to the present invention; 
           [0138]      FIGS. 30 and 31  illustrate spoilers of the baffle shown in  FIG. 29 ; 
           [0139]      FIG. 32  illustrates a heat transfer sheet of the baffle shown in  FIG. 29 ; 
           [0140]      FIG. 33  is a schematic view of a fourteenth embodiment of the baffle according to the present invention; 
           [0141]      FIG. 34  is a schematic view of a heat conducting cylinder used in the baffle shown in  FIG. 33 ; 
           [0142]      FIG. 35  is a perspective view showing the baffle shown in  FIG. 33  installed in the heat exchanger; 
           [0143]      FIG. 36  is a schematic view of a second embodiment of the heat exchanger according to the present invention; 
           [0144]      FIG. 37  is a schematic view of a fifteenth embodiment of the baffle according to the present invention; 
           [0145]      FIG. 38  is a schematic view of a sixteenth embodiment of the baffle according to the present invention; 
           [0146]      FIG. 39  is a schematic view of a seventeenth embodiment of the baffle according to the present invention; 
           [0147]      FIG. 40  is a schematic view of a circular fluid pipeline internally provided with a plurality of parallel spiral metal wires clinging thereto which forms the baffle of  FIG. 37 or 38  after flattening; 
           [0148]      FIG. 41  is a perspective view of a third embodiment of the heat exchanger according to the present invention; 
           [0149]      FIG. 42  is an exploded perspective view of the heat exchanger shown in  FIG. 41 ; 
           [0150]      FIGS. 43 and 43A  is a perspective view of a flow divider used in the heat exchanger shown in  FIG. 41 ; 
           [0151]      FIG. 44  is a schematic view of a filtration device in the heat exchanger shown in  FIG. 41 ; 
           [0152]      FIGS. 45 and 45A  is a sectional perspective view of the heat exchanger shown in  FIG. 41 ; 
           [0153]      FIG. 46  is a sectional perspective view of the main body of the heat exchanger shown in  FIG. 41 ; 
           [0154]      FIG. 47  is an exploded perspective view of a nested structure of a heat exchange pipe; 
           [0155]      FIG. 48  is a sectional perspective view of a heat exchanger identical to that of  FIG. 45 , illustrating an operation of removing fouling of the heat exchange pipe; 
           [0156]      FIG. 49  is a perspective view of a baffle forming the second embodiment of the flow divider according to the present invention; 
           [0157]      FIG. 50  is a perspective view showing the baffle shown in  FIG. 49  installed in the heat exchanger; 
           [0158]      FIG. 51  is a perspective view of a situation where the main body of the heat exchanger shown in  FIG. 42  is disposed with an annular channel; 
           [0159]      FIG. 52  is a sectional perspective view of an eighteenth embodiment of the baffle according to the present invention; 
           [0160]      FIGS. 53-54  are perspective views of a spoiler in the eighteenth embodiment of the baffle according to the present invention; 
           [0161]      FIG. 55  is a perspective view of a heat transfer sheet in the eighteenth embodiment of the present invention; 
           [0162]      FIG. 56  is a sectional perspective view of a nineteenth embodiment of the baffle according to the present invention; 
           [0163]      FIG. 57  is a perspective view of a spoiler in the nineteenth embodiment of the baffle according to the present invention; 
           [0164]      FIG. 58  is a sectional perspective view of a twentieth embodiment of the baffle according to the present invention; 
           [0165]      FIGS. 59-60  are perspective views of a spoiler in the twentieth embodiment of the baffle according to the present invention; 
           [0166]      FIG. 61  is a perspective view of a heat transfer sheet in the twentieth embodiment of the baffle according to the present invention; 
           [0167]      FIG. 62  is a sectional perspective view of a twenty-first embodiment of the baffle according to the present invention; 
           [0168]      FIG. 63  is an exploded perspective view of the twenty-first embodiment of the baffle according to the present invention; 
           [0169]      FIG. 64  is a sectional perspective view of a twenty-second embodiment of the baffle according to the present invention; 
           [0170]      FIG. 65  is a perspective view of a spoiler in the twenty-second embodiment of the baffle according to the present invention; 
           [0171]      FIG. 66  is an exploded perspective view of the twenty-second embodiment of the baffle according to the present invention; 
           [0172]      FIG. 67  is a sectional perspective view of a twenty-third embodiment of the baffle according to the present invention; 
           [0173]      FIG. 68  is a perspective view of a spoiler in the twenty-third embodiment of the present invention; 
           [0174]      FIG. 69  is an exploded perspective view of a fourth embodiment of the heat exchanger according to the present invention and a bathroom drain device; 
           [0175]      FIG. 70  is a perspective view of an assembling state of the heat exchanger and the bathroom drain device shown in  FIG. 69 ; 
           [0176]      FIG. 71  is an exploded perspective view of the heat exchanger shown in  FIG. 69 ; 
           [0177]      FIG. 72  is a sectional perspective view of an assembling state of the heat exchanger shown in  FIG. 69 ; 
           [0178]      FIG. 73  is an exploded perspective view of the heat exchange pipe shown in  FIG. 69 ; 
           [0179]      FIG. 74  is a perspective view of a nested state of the heat exchange pipe shown in  FIG. 73 ; 
           [0180]      FIG. 75  is a schematic view of a fifth embodiment of the heat exchanger according to the present invention being placed on the bathroom floor; 
           [0181]      FIG. 76  is an exploded perspective view of the heat exchanger and a water collector shown in  FIG. 75 ; 
           [0182]      FIG. 77  is an exploded perspective view of the heat exchanger shown in  FIG. 75 ; and 
           [0183]      FIG. 78  is a schematic view of an internal baffle structure of a heat exchange pipe in the heat exchanger shown in  FIG. 75 . 
       
    
    
     DETAILED DESCRIPTION 
       [0184]    The present invention relates to a thermal conductive baffle, a fluid heat exchanger and an energy recovery device. Embodiments in which the thermal conductive baffle, the fluid heat exchanger and the energy recovery device of the present invention are combined with a bathroom shower and a sink of a washing facility are described below only by way of examples with reference to the accompanying drawings. It should be understood that the present invention is not limited thereto. 
         [0185]      FIGS. 2, 2A, 3 and 4  illustrate a structure of a first embodiment of a fluid heat exchanger according to the present invention. The heat exchanger  1  includes a heat exchanger main body  11  and a baffle  31 . The heat exchanger main body  11  includes a housing  13  and a metal pipe  15 . The housing  13  has a cold water (second fluid) inlet  17 , a tepid water (preheated second fluid) outlet  18  and a cold water (second fluid) conduit  19  between the cold water inlet  17  and the tepid water outlet  18 . The metal pipe  15  is vertically disposed in the cold water conduit  19  and passes through the housing  13 , and a hot wastewater (first fluid) channel  21  for hot wastewater (first fluid) to pass through is formed in the metal pipe  15 . A protruding baffle structure  22  is disposed on an inner wall of the metal pipe  15 . The baffle structure  22  is formed by one or more solid metal spiral structures extending along a length direction of the metal pipe  15 , and maintains good thermal contact with the inner wall of the metal pipe  15 . The baffle structure  22  can be assembled into the metal pipe  15  in the following manner: 
         [0186]    a. spiraling and coiling one or more solid metal wires on a straight bar with gaps, to such that overall outer diameter thereof less than the inner diameter of the metal pipe  15 ; 
         [0187]    b. placing the straight bar and the metal wires together in a suitable position within the metal pipe  15 ; 
         [0188]    c. loosening the metal wires, such that the metal wires naturally rebound to press against the inner wall of the metal pipe  15 ; and 
         [0189]    d. removing the straight bar. 
         [0190]    A cold water (second fluid) annular channel  23  ( FIG. 3 ) surrounding an outer wall of the metal pipe  15  is formed between the metal pipe  15  and the cold water conduit  19 . In the following description about various embodiments of the present invention, the first fluid is hot wastewater and the second fluid is cold water as an example for illustration, but the present invention is not limited thereto. 
         [0191]    During the operation of the heat exchanger  1 , the cold water inlet  17  is directly or indirectly connected to a cold water source (not shown) of a building, the tepid water outlet  18  is connected to a bathroom heater (not shown) or a mixing valve (not shown), and the hot wastewater channel  21  is communicated to a drain pipe (not shown) of a shower device or the like to receive hot wastewater generated during shower. The inner diameter of the hot wastewater channel  21  is designed such that hot wastewater generated generally by shower is not sufficient to fill its cavity. The hot wastewater attaches to an inner wall of the hot wastewater channel  21  to slowly flow downwards. The baffle structure  22  slows down the speed at which the hot wastewater flows downwards, and facilitates the spiral motion of the hot wastewater in the metal pipe  15  to delay the time period of its stay in the hot wastewater channel  21 . In the meantime, heat exchange surfaces of the hot wastewater is also significantly increased. These all effectively enhance heat exchange efficiency of the heat exchanger. To further enhance the efficiency of heat conduction between the baffle structure  22  and the metal pipe  15  and prevent the baffle structure  22  from shifting, a layer of solder may be pre-coated on surfaces of the metal wires. After the metal wires are placed in the metal pipe  15 , relevant parts may be placed in a high-temperature furnace for heating, so that the solder melts to braze the baffle structure onto the inner wall of the metal pipe  15 . Certainly, the baffle structure is optional, which may be omitted in the following drawings and description of embodiments. 
         [0192]    To reduce that fouling (such as hair) accumulated on one or more open ends of the top (upstream) of the protruding spiral structure  22  affecting the drainage effect, the open ends may form a slope  10  ( FIG. 2 ) that facilitates the fouling to slide or may be covered by another ring  29  as illustrated in  FIG. 2   a.    
         [0193]    Meanwhile, the cold water is introduced from the cold water inlet  17  to flow through the cold water annular channel  23  from the bottom up, and exchanges heat with hot wastewater flowing through the hot wastewater channel  21  by means of the metal pipe  15 , so that the temperature of the cold water is changed and the cold water becomes preheated water, and then exported from the tepid water outlet  18  and provided to the bathroom heater or the mixing valve (not shown) for use. 
         [0194]    As shown in  FIGS. 2-4 , the metal pipe  15  is formed by mutual nesting of two metal pipes, i.e., an external metal pipe  25  and an internal metal pipe  26 , and the external metal pipe  25  and the internal metal pipe  26  maintain good thermal contact therebetween, and leave a micro-channel  27  that can allow the wastewater or cold water to pass through. The micro-channel  27  is formed between the external metal pipe  25  and the internal metal pipe  26  by having small concave-convex structures on a surface of the internal metal pipe  26  through knurling or the like. Under normal conditions, no cold water or wastewater seeps leak out from the micro-channel  27  between the external metal pipe  25  and the internal metal pipe  26 . However, when one of the external metal pipe  25  or the internal metal pipe  26  is damaged to cause seepage of cold water or hot wastewater, the cold water or hot wastewater may flow out of the heat exchanger  1  through the micro-channel  27  and alert the user. Certainly, the nested structure is optional, and for the sake of simplicity, in the following drawings and description, the metal pipe  15  may be illustrated and described in the form of a single piece. 
         [0195]    The heat exchanger  1  in the first embodiment of the fluid heat exchanger according to the present invention further includes a baffle  31 , to further improve the heat exchange efficiency. As shown in  FIG. 4 , the baffle  31  surrounding the metal pipe  15  is disposed in the cold water annular channel  23  formed by tubes, i.e., the metal pipe  15  and the cold water conduit  19 . The baffle  31  is made of metal, which tightly presses against on the inner wall of the cold water conduit  19  and maintains good thermal contact with the outer wall of the metal pipe  15 . A manner in which the baffle  31  is installed may include welding, or after the baffle  31  is placed, the inner diameter of the metal pipe  15  is slightly expanded so that the outer wall of the metal pipe  15 , the baffle  31  and the inner wall of the cold water conduit  19  pressed together. 
         [0196]      FIGS. 2, 3 and 4  illustrate a structure of a first embodiment of a thermal conductive baffle according to the present invention. The baffle  31  includes a plurality of solid metal strips  33  (see  FIG. 5 ). A plurality of solid annular projections  34  is spaced apart along a length direction of the metal strips  33 . The plurality of solid metal strips  33  is adjacently configured around the outer wall of the metal pipe  15  with their centerlines parallel to the centerline of the metal pipe  15 . The cold water is blocked by the plurality of metal strips  33  when passing through the cold water annular channel  23 , and the cold water passes through between the outer wall of the metal pipe  15 , the metal strips  33 , the annular projections  34  and the inner wall of the cold water conduit  19  in turbulence, and exchanges heat with the hot wastewater flowing through the hot wastewater channel  21  by means of heat conduction of the baffle  31  and the metal pipe  15 . The thermal conductive baffle  31  significantly increases the heat exchange surface with the cold water, and can constantly change the flow direction of the cold water to generate a turbulence effect, thereby improving the heat exchange efficiency. The cold water conduit  19  may also be made of metal, so that the inner wall of the cold water conduit  19  also becomes the heat exchange surface with the cold water. 
         [0197]      FIG. 6  illustrates a structure of a second embodiment of a thermal conductive baffle according to the present invention. The baffle  41  is made of one or more solid metal strips  33  as shown in  FIG. 5 . The metal strips  33  spirally extend with their centerlines around the outer wall of the metal pipe  15 . The function and the effect of the baffle  41  are substantially the same as those of the baffle  31 , which are not repeated herein. 
         [0198]      FIGS. 7-9  illustrate a structure of a third embodiment of a thermal conductive baffle according to the present invention. The baffle  41 ′ includes a plurality of solid metal strips  36  made of metal. A plurality of solid annular projections  37  are spaced apart from each other along a length direction of the metal strips  36 . Each of the metal strips  36  surrounds the metal pipe with its centerline perpendicular to the centerline of the metal pipe  15 , and the annular projections  37  of adjacent metal strips  36  are staggered. The function and the effect of the baffle  41 ′ are substantially the same as those of the baffle  31 , which are not repeated herein. 
         [0199]    To facilitate assembly of the plurality of metal strips  36 , planes  38  back to each other may be formed on the solid annular projections  37 , and then the metal strips  36  are fixed to a metal sheet  39  by means of the planes  38 . Afterwards, the metal sheet  39  is bent into a cylindrical shape ( FIG. 9 ) to be nested onto the metal pipe  15 , and another plane  38  of the annular projections  37  is pressed against the metal pipe  15 . In this way, a contact area of the baffle  41 ′ and the metal pipe  15  is increased, and the thermal conductive function is enhanced. 
         [0200]      FIGS. 10-11  illustrate a structure of a fourth embodiment of a thermal conductive baffle according to the present invention. The baffle  51  includes a plurality of spiral spring-like metal strips  53  (see  FIG. 11 ) made of solid metal wires. The metal strips  53  are adjacently configured around the outer wall of the metal pipe  15  with their centerlines parallel to the centerline of the metal pipe  15 . The function and the effect of the baffle  51  are substantially the same as those of the baffle  31 , which are not repeated herein. 
         [0201]      FIG. 12  illustrates a structure of a fifth embodiment of a thermal conductive baffle according to the present invention. The baffle  61  is formed by one or more metal strips  53  as shown in  FIG. 11 . The metal strips  53  spirally extend with their centerlines around the outer wall of the metal pipe  15 . The function and the effect of the baffle  61  are substantially the same as those of the baffle  31 , which are not repeated herein. 
         [0202]    Similarly, the metal strips  53  shown in  FIG. 12  may also surround the metal pipe with their centerlines perpendicular to the centerline of the outer wall of the metal pipe  15 , so as to construct a baffle (not shown) similar to the baffle shown in  FIG. 7 . 
         [0203]      FIGS. 13-14  illustrate a structure of a sixth embodiment of the baffle having a thermal conductive baffle according to the present invention. The baffle  71  includes a plurality of metal strip  75 , each comprises a first spiral spring-like metal element  73  (see  FIG. 14 ) and a second metal strips  74  extending along the center of the spiral element  73  to increase the heat exchange surface. The second metal strips  74  shown in  FIG. 14  are straight bars, but they may be various kinds of metal strips described previously or below. The metal strips  75  are adjacently configured around the outer wall of the metal pipe  15  with their centerlines parallel to the centerline of the metal pipe  15 . The function and the effect of the baffle  71  are substantially the same as those of the baffle  31 , which are not repeated herein. 
         [0204]    Similarly, one or more metal strips  75  shown in  FIG. 14  may spirally extend with their centerlines around the outer wall of the metal pipe  15 , or the plurality of metal strips surrounds the metal pipe with their centerlines perpendicular to the centerline of the metal pipe  15 , so as to construct a baffle (not shown) similar to the baffle shown in  FIGS. 6 and 7 . 
         [0205]      FIGS. 15-16  illustrate a structure of a seventh embodiment of a thermal conductive baffle according to the present invention. The baffle  81  includes a plurality of metal strips  83  (see  FIG. 16 ), and each of the metal strips  83  is made by intertwining of two solid metal wires  84  and  85 , on whose surface there is a spiral concave structure. The metal strips  83  are adjacently configured around the outer wall of the metal pipe  15  with their centerlines parallel to the centerline of metal pipe  15 . The metal strips may also be formed by intertwining of a plurality of metal wires. The function and the effect of the baffle  81  are substantially the same as those of the baffle  31 , which are not repeated herein. 
         [0206]    Similarly, one or more metal strips  83  shown in  FIG. 16  can spirally extend with their centerlines around the outer wall of the metal pipe  15 , or the plurality of metal strips  83  surrounds the outer wall of the metal pipe with their centerlines perpendicular to the centerline of the metal pipe  15 , so as to construct a baffle (not shown) similar to the baffle shown in  FIGS. 6 and 7 . 
         [0207]      FIGS. 17-18  illustrate a structure of an eighth embodiment of a thermal conductive baffle according to the present invention. The baffle  91  includes a plurality of metal spiral strips  93  having rectangular or non-circular cross-sections, on whose surfaces there are spiral concave structures  95  (see  FIG. 18 ). The metal spiral strips  93  are adjacently configured around the outer wall of the metal pipe  15  with their centerlines parallel to the centerline of the metal pipe  15 . The function and the effect of the baffle  91  are substantially the same as those of the baffle  31 , which are not repeated herein. 
         [0208]    Similarly, one or more metal spiral strips  93  shown in  FIG. 18  can spirally extend with their centerlines around the outer wall of the metal pipe  15 , or the plurality of metal strips  93  surrounds the outer wall of the metal pipe with their centerlines perpendicular to the centerline of the metal pipe  15 , so as to construct a baffle (not shown) similar to the baffle shown in  FIGS. 6 and 7 . 
         [0209]      FIGS. 19-20  illustrate a structure of a ninth embodiment of the baffle having a thermal conductive baffle according to the present invention. The baffle  101  has a barrel structure made by stamping of metal, and is formed by two semi-barrel structures  102  and  103 , on whose surfaces there are a plurality of spiral pits  104  and  105  to form a plurality of spiral channels that allows the cold water to flow through in parallel, and a plurality of straight-through through holes  106  and  107  is further provided between the spiral pits  104  and  105  to allow part of the cold water to directly pass through adjacent spiral channels with a non-circuitous straight-through path to generate turbulence effects.  FIG. 21  illustrates a state in which the baffle  101  is installed in the heat exchanger main body  11 . The cold water exchanges heat with the hot wastewater flowing through the hot wastewater channel  21  by means of heat conduction of the baffle  101  and the metal pipe  15  when flowing through the plurality of spiral channels in parallel. 
         [0210]      FIG. 22  illustrates a structure of a tenth embodiment of the thermal conductive baffle according to the present invention. The baffle  111  includes two layers of helically configured un-parallel (preferably with reverse helical direction) solid metal wires  112  and  113  overlapping each other that surround the metal pipe  15 . Each layer of metal wires  112  and  113  includes a plurality of metal wires sections spaced apart and parallel to each other where the metal wires  112  in the inner layer presses against and thermally contacts the outer wall of metal pipe  15  along the majority of their length, while the metal wires  113  in the outer layers butts against the inner wall of the cold water conduit  19 . The cold water passing through the annular channel  23 , flows through gaps  114  (see  FIG. 23 ) between the two layers of wires  112  and  113  and exchanges heat with hot wastewater in the wastewater channel  21 . The baffle  111  significantly increases the heat exchange surface of cold water and constantly changes the flow direction; these are helpful to improve the heat exchange efficiency of the heat exchanger. 
         [0211]    The baffle  111  with thermal conductive function as illustrated in  FIG. 22  may be fabricated by method as illustrated in  FIG. 22  A: 
         [0212]    1. A plurality of metal wires  112 A,  112 B,  112 C and  112 D are spirally arranged about mandrel  114  with gaps and in parallel, to form an inner metal wire layer  112 ; 
         [0213]    2. Upon spirally arranged about mandrel  114  for a certain of length, the plurality of metal wire  112 A,  112 B,  112 C and  112 D are further spirally arranged about mandrel  114  in counterclockwise direction with gaps and in parallel, to form an outer metal wire layer  113 ; 
         [0214]    3. Prior to relieving or cutting the plurality of metal wires  112 A,  112 B,  112 C and  112 D, the two metal wire layers are welded in suitable position with suitable means (such as spot welding) to form a rigid metal tubular mesh; 
         [0215]    4. The metal wires are removed from mandrel  114  and then cutting into suitable length to form the baffle as illustrated in  FIG. 22 . 
         [0216]    In the aforementioned example, mandrel  114  may also be replaced by metal tube  15  and directly weld the plurality of metal wires  112 A,  112 B,  112 C and  112 D thereon. 
         [0217]    By using the method as above, baffle with more than two metal wire layers may be fabricated to increase heat exchange surface and enhance turbulence effect.  FIGS. 24-25  illustrate a structure of an eleventh embodiment of the thermal conductive baffle according to the present invention. Structure of baffle  121  is basically same as baffle  111  ( FIG. 22 ) except that it is formed by curling a metal mesh  121 ′ as shown in  FIG. 25 . The metal mesh  121 ′ includes two layers of metal wires. Each layer includes a plurality of solid straight metal wires  122 ′ and  123 ′ parallel to each other and spaced apart. The two layers are superposed and welded with the wires unparallel to form the mesh  121 ′. The function and effect of the baffle  121  are substantially the same as those of baffle  111 , which are not repeated herein. 
         [0218]      FIG. 26  illustrates a structure of a twelfth embodiment of a thermal conductive baffle according to the present invention,  FIG. 27  illustrates a shape of the metal strips  132  for manufacturing the baffle  131 , and  FIG. 28  illustrates a state in which the baffle  131  is installed in the heat exchanger main body  11 . The baffle  131  has a barrel structure made by cutting of metal strip  132  after curling. Multiple pairs of mutually aligned solid spoilers  134  and  135  functioning to baffle flow are convexly formed on internal and external surfaces of cylindrical walls  133  respectively, and the spoilers  134  and  135  maintain good thermal contact with the outer wall of the metal pipe  15  and press against the inner wall of the conduit  19 . The cylindrical walls  133  and the spoilers  134  and  135  respectively form two groups of internal and external spiral channels  136  and  137  in the cold water annular channel  23 . The cold water passes through the two groups of internal and external spiral channels  136  and  137  in parallel. Due to heat conduction of the mutually aligned solid spoilers  134  and  135  of the baffle  131  as well as the cylindrical walls  133  and the metal pipe  15 , the heat exchange surface with the cold water is significantly increased, thereby improving the heat exchange efficiency. The spoilers  134  and  135  are further respectively provided with a plurality of substantially aligned notches  138  and  139 , to allow part of the cold water to directly pass through two adjacent spiral channels  136  and  137  with a non-circuitous straight-through path, thereby generating turbulence effects. 
         [0219]      FIG. 29  to  FIG. 32  illustrate a structure of a thirteenth embodiment of a thermal conductive baffle according to the present invention. The baffle  55  is horizontally superposed in the annular channel  23  ( FIG. 29 ) through sheet-like objects as shown in  FIG. 30  to  FIG. 32  with gaps, and the sheet-like objects  56 ,  57  and  58  ( FIGS. 30-32 ) all have central through holes ( 561 ,  581  and  571 ) for tightly nesting the metal pipe  15  and openings that allow the fluids to pass, where the opening  562  of the sheet-like object  56  ( FIG. 30 ) is formed in adjacent to the central through hole  561 , the opening  574  of the sheet-like object  57  ( FIG. 31 ) is formed by a gap between a periphery  572  thereof and the inner wall of the cold water conduit  19 , and the sheet-like object  58  ( FIG. 32 ) has two openings, including an opening  582  formed adjacent to the central through hole  581  and an opening  584  formed by a gap between a periphery  583  thereof and the inner wall of the cold water conduit  19 . The sheet-like objects  56 ,  57  and  58  are at least partially made of metal (in the above example, the sheet-like objects  56 ,  57  and  58  are all made of metal) and thermally contact the outer wall of the metal pipe  15 . The sheet-like objects  56  and  57  are spoilers, and any two closest spoiler  56  and  57  when placed in the annular channel  23  ( FIG. 29 ), whose openings do not overlap each other in a main surface direction, so that the cold water passing through the annular channel  23  needs to circuitously flow between the baffle spoiler  56  and  57  alternately from inside to outside and then from outside to inside so as to alternately pass through the openings  562  and  574  to form turbulence effects, and increase the rate of heat exchange. 
         [0220]    To further increase heat transfer effects, one or more metal heat transfer sheets  58  may be added between the spoiler  56  and  57 . When the cold water passing through the annular channel  23  passes through any two closest spoiler  56  and  57 , the cold water passes in parallel through two main surfaces of the heat transfer sheets  58 , and exchanges heat with the hot wastewater passing through the metal pipe  15  by means of the heat transfer sheets  58  and the metal pipe  15 . The metal sheet-like object  56 ,  57  or  58  significantly increases the heat exchange surface of the cold water; the spoiler  56  and  57  constantly change the flow direction of the cold water to generate turbulence effects; these are all helpful to improve the heat exchange efficiency of the heat exchanger  11 . 
         [0221]      FIGS. 33-35  illustrate a structure of a fourteenth embodiment of a thermal conductive baffle according to the present invention. The baffle  141  is similar to the baffle  111  in the tenth embodiment, and includes two layers of un-paralleled solid metal wires  142  and  143  overlapping each other to surround the metal pipe  15 . The difference merely lies in that a heat conducting cylinder  144  is disposed between the two layers of metal wires  142  and  143  of the baffle  141 . A plurality of through holes  146  is formed on cylinder walls  145  of the heat conducting cylinder  144 .  FIG. 35  illustrates a state in which the baffle  141  is installed in the heat exchanger main body  11 . The heat conducting cylinder  144  partitions the cold water annular channel  23  into internal and external annular channels, the solid metal wires  142 / 143  thereby forming two groups of cold water spiral channels. Part of the cold water spirally passes through the two groups of cold water spiral channels, and part of the cold water passes through the through holes  146  on the heat conducting cylinder  144  between the metal wires, to generate turbulence effects. The baffle  141  significantly increases the heat exchange surface of the cold water, thereby enhancing the heat exchange efficiency of the heat exchanger. In this embodiment, the metal wires  142  and  143  respectively constitute internal and external baffles, and the internal and external baffles may be any one or a combination of any two of the baffles in the first to thirteenth embodiments. Due to the thermal conduction of the heat conducting cylinder  144 , the internal and external baffles and the metal pipe  15 , the heat exchange surface with the cold water is significantly increased, thereby enhancing the heat exchange efficiency. 
         [0222]    In the foregoing embodiments, pipe  15  and the thermal conductive baffles are made of metal, preferably they should be made of good thermal conductors such as copper or aluminium or its alloy to enhance heat exchange. Optionally, cold water conduit  19  can also be made of metal so that its internal wall becomes a heat exchange surface to enhance heat exchange. 
         [0223]    In the foregoing embodiments, the thermal conductive baffles are placed in an annular channel formed by 2 tubes (metal pipe  15  &amp; cold water conduit  19 ) which includes at least one metal wall (metal pipe  14 ) and is in thermal contact with at least one metal wall (metal pipe  15 ) that form the annular channel. Fluid (cold water) exchange heat with hot wastewater (second fluid) outside the annular channel. But optionally, other substance, such as electric heating wires, can be placed outside the annular channel, for example, inside metal pipe  15  or outside cold water conduit  19 , so that the heat exchanger can serve as a fluid heater. If an electric heating wire is placed outside the cold water conduit, the metal pipe  15  may be replaced by a solid member. 
         [0224]      FIG. 36  illustrates a second embodiment of the heat exchanger according to the present invention. The heat exchanger  32  includes a metal pipe  15  and a metal cold water conduit  42  spirally surrounding the metal pipe  15 , which tightly nests and thermally contacts the metal pipe  15 . A section of the cold water conduit  42  is flat, and a section on an outer wall thereof has at least one straight side and clings to an outer wall of the metal pipe  15  so as to increase a contact surface with the metal pipe  15 . 
         [0225]    In use of the heat exchanger  32 , an inlet  43  (cold water inlet) of the cold water conduit  42  located in the bottom is directly or indirectly connected to a cold water source (not shown) of the building; an outlet  44  (tepid water outlet) on the top thereof is connected to a bathroom heater (not shown) or a bathroom mixing value (not shown). Like the heat exchanger  11  in the first embodiment, the hot wastewater channel  21  of the heat exchanger  32  is communicated to a drain pipe (not shown) of a shower device or the like to receive hot wastewater generated during shower. The hot wastewater passes through the metal pipe  15  in a manner identical to that in the first embodiment, which is not repeated herein. 
         [0226]    In the meantime, the cold water is introduced from the cold water inlet  43  to flow through the spiral conduit  42  from the bottom up, and exchanges heat with hot wastewater flowing through the hot wastewater channel  21  by means of the metal pipe  15 , so that the temperature of the cold water is changed and the cold water becomes preheated water, and then is exported from the tepid water outlet  44  and provided to the bathroom heater or mixing valve (not shown) for use. 
         [0227]    To increase the heat exchange efficiency, the spiral protruding structure in the first embodiment ( FIG. 2 ) can optionally be added to the wastewater channel  21 , the function of which is not repeated herein; meanwhile, a thermal conductive baffle as shown in  FIG. 37, 38 or 39  may also be added to the cold water conduit  42 . 
         [0228]    As shown in  FIG. 37 , the baffle  35  is placed in a metal fluid conduit  42 ′, a fluid channel  45  formed on an inner wall of the fluid conduit  42 ′ has two parallel surfaces  47  and  48 . The baffle is formed by upper and lower layers of metal wires  49  and  52 , each layer of metal wires is formed by a plurality of metal wire sections parallel to each other and arranged with gaps, and each layer of metal wires (thermally) contacts the two parallel surfaces  47  and  48  respectively. Part of wire sections in the two layers of metal wires are formed by the same metal wire and are connected through bends  54  and  59 . Fluids passing through the fluid channel  45  pass between the two layers of metal wires  49  and  52  and between various sections of parallel metal wires in turbulence, and exchange heat with substances outside the channel  45  (for example, the hot waste water in the metal pipe  15 ) by means of the two layers of metal wires  49  and  52  and walls of metal channels in thermal contact therewith. 
         [0229]    One or more metal fluid conduit  42 ′ having the baffle  35  as shown in  FIG. 37  may tightly be wound to the outer wall of the metal pipe  15  to form the heat exchanger  32  ( FIG. 38 ). The baffle  35  in the fluid channel  45  significantly increases the heat exchange surface of the cold water, and constantly changes the flow direction of the cold water, to effectively improve heat exchange effects. 
         [0230]    The fluid channel having the heat conducting baffle  35  may be manufactured in the following manner: 
         [0231]    a. coiling one or more metal wires on a straight bar with gaps, such that an overall outer diameter thereof slightly less than the inner diameter of a circular metal pipe; 
         [0232]    b. placing the straight bar and the metal wires together in a suitable position in the metal pipe; 
         [0233]    c. loosening the metal wires, such that the metal wires are naturally rebound to press against the inner wall of the metal pipe; 
         [0234]    d. removing the straight bar, to form a circular fluid conduit having a plurality of parallel spiral metal wires clinging thereto as shown in  FIG. 40 ; and 
         [0235]    e. flattening the circular metal pipe to form the fluid pipeline of the baffle having a thermal conductive baffle as shown in  FIG. 37 or 38 . 
         [0236]    The difference between  FIG. 37  and  FIG. 38  lies in that: for the baffle  35  shown in  FIG. 37 , the upper and lower layers of metal wires thereof are tightly pressed together, so that heat can be rapidly transferred from one parallel surface to the other parallel surface through thermal conduction between the two layers of metal wires; and for the baffle  35 ′ (in the sixteenth embodiment) shown in  FIG. 38 , the upper and lower layers of metal wires thereof leave a gap therebetween, to allow more fluids to pass through and result in smaller pressure loss, and technicians can choose to use the baffle according to situations. 
         [0237]      FIG. 39  illustrates a seventeenth embodiment of the baffle according to the present invention. The baffle  62  is disposed in a metal fluid channel  45 , and the fluid channel  45  has two parallel surfaces  47  and  48 . The baffle is formed by superposition of four layers of metal wires  63 ,  64 ,  65  and  66  which are pressed together to provide thermal contact there between, each layer of metal wires has a plurality of metal wire sections parallel to each other and having gaps, and metal wire sections in two adjacent layers of metal wires are not parallel to each other. The metal wire  63  in the top layer (thermally) contacts the upper parallel surface  48  of the fluid channel  45 ; the metal wire  66  in the bottom layer (thermally) contacts the lower parallel surface  47  of the fluid channel  45 , and part of sections of the metal wires  63  and  66  in the top layer and the bottom layer are formed by the same metal wire, and are connected through bends  67  and  67 ′. Part of sections of two layers of metal wires  64  and  65  in the middle are formed by the same metal wire and are connected through bends  68  and  68 ′. The fluids passing through the fluid channel  45  pass through the four layers of metal wires and the parallel metal wire sections in turbulence, and exchange heat with substances outside the channel (for example, the hot waste water in the metal pipe  15 ) by means of the metal wires and metal walls of fluid channels in thermal contact therewith. 
         [0238]    One or more metal fluid channels  42 ′ having the baffle  62  as shown in  FIG. 39  may tightly be wound to the metal pipe  15  to form the heat exchanger  32  ( FIG. 36 ). The baffle  62  significantly increases the heat exchange surface of the cold water, and constantly changes the flow direction of the cold water, which are helpful to improve heat exchange effects. 
         [0239]    The fluid channel having the baffle  62  may be manufactured in the following manner: 
         [0240]    a. placing the net-like metal cylinder shown in  FIG. 22 or 24  into a metal circular pipe whose inner diameter is slightly greater than that of the net-like cylinder; and 
         [0241]    b. flattening the metal circular pipe and the net-like cylinder together such that the circular pipe form two parallel surfaces and tightly press the (four layers of) metal wires. 
         [0242]      FIG. 41  illustrates a third embodiment of the heat exchanger according to the present invention. The heat exchanger  160  is installed below a sink  162  and a tabletop  163 . As shown in  FIG. 42 , the heat exchanger  160  includes a wastewater collector  165 , a main body  167  and a wastewater connector  169 . The wastewater collector  165  has an opening  172 , a cavity  173  and a plurality of wastewater outlets  174 . The opening  172  is located above the plurality of wastewater outlets  174 , and covers all the wastewater outlets  174  in a horizontal direction. The main body  167  includes a housing  177  and a plurality of heat exchange pipes  179 . The wastewater connector  169  has a plurality of wastewater receiving holes  182  and wastewater discharge ports  183 . The opening  172  of the wastewater collector  165  communicates with a drain hole  161  of the sink  162 , to receive hot wastewater generated during washing. The drain hole  161  covers all the wastewater outlets  174  in a horizontal direction. The hot wastewater flows into the cavity  173  through the opening  172  of the wastewater collector and then flows out of the cavity  173  in parallel from the plurality of wastewater outlets  174 . The plurality of wastewater outlets  174  separately communicates with the plurality of heat exchange pipes  179 , such that the hot wastewater pass through hot wastewater channels  185  in parallel. The hot wastewater, enters the wastewater connector  169  from the plurality of wastewater receiving holes  182  after passing through the main body  167 , and is then discharged from the wastewater discharge ports  183  to a drain pipeline (not shown) outside the building. 
         [0243]    To ensure the wastewater flow out from the plurality of wastewater outlets  174  evenly and avoid that the wastewater only rapidly flows out from one or two wastewater outlets to affect the heat exchange efficiency, a flow divider  181  (see  FIG. 43 ) may detachably be disposed in the cavity  173 . The flow divider  181  includes a chassis  1811 , a riser  1812  extending upwards from the chassis  1811  and an upper cover  1813  covering an upper end of the riser  1812 . The chassis  1811  is provided with a plurality of baffles  1814  corresponding to the wastewater outlets  174 . The baffles  1814  are adjacent to or placed in inlet ends of the wastewater outlets  174  respectively, so that the wastewater is blocked by the baffles  1814  to pass through gaps  180  (see  FIG. 45 ) between the baffles  1814  and the wastewater outlets  174  with relatively even flow in entering the wastewater channels  185 . The quantity of wastewater flow is insufficient to fill the whole wastewater channels  185 , and thus the wastewater is attached to inner walls of the wastewater channels  185  and flows downwards around a central air column of the wastewater channels  185 . 
         [0244]    The baffles  1814  have through holes  1815 , which communicate with the riser  1812 . An air vent  1817  is formed on the upper end of the riser  1812 . The wastewater, when passing through the baffles  1814 , forms low pressure in the vicinity of the through holes  1815 , to suck air into the wastewater channels  185  from the air vent  1817 , so that the air can still enter the wastewater channels  185  when the wastewater floods the wastewater outlets  174  to maintain the state of having the central air column. 
         [0245]    Alternatively, as shown in  FIG. 43A , Baffles  1814  of the flow divider  181  may include gaps  1818 . When inserted in the wastewater outlet  174  ( FIG. 45A ) the Baffles  1814  contacts the waste water outlet  174  and the gap  1818  form passageway  182  for wastewater to evenly flow through. 
         [0246]    The downward flowing wastewater, exchanges heat with cold water flowing reversely outside the heat exchange pipes through the heat exchange pipes  179 . 
         [0247]    To reduce the fouling accumulated and clogged in the wastewater channels  185 , a strainer  64  as shown in  FIG. 44  may be disposed in the cavity  173  of the wastewater collector  165  for separating hair and other garbage. The strainer  64  has a through hole  641  located in the center to allow the riser  1812  to pass through and small holes  642  located in the periphery to allow the wastewater to pass through. The strainer  64  and the flow divider  181  are detachably installed in the cavity  173  of the wastewater collector  165  such that a user may remove the strainer  64  and the flow divider  181  at the opening  172  for cleaning. 
         [0248]    As shown in  FIG. 45 , a protruding baffle structure  186  can be formed on the inner walls of the wastewater channels  185  to improve the heat exchange efficiency, where the function, effect, and assembly method are substantially the same as those of the baffle structure  22  shown in  FIG. 3 , and thus are not repeated herein. Similarly, the baffle structure is optional, and such baffle structure may be omitted in the following drawings and description for the sake of simplicity. 
         [0249]      FIG. 46  illustrates an internal structure of the heat exchanger  160 . The housing  177  has a cold water inlet  192  and a tepid water outlet  193 . The plurality of heat exchange pipes  179  communicates with the plurality of wastewater outlets  174  and the plurality of wastewater receiving holes  182  respectively, such that the hot wastewater pass through from the hot wastewater channels  185  in parallel. The hot wastewater enters the wastewater connector  169  after passing through the main body  167 . During operation, the cold water inlet  192  is directly or indirectly connected to a cold water source (not shown) of the building, and the tepid water outlet  193  is connected to a heater (not shown) outside the sink  162  or mixing valve (not shown). Hot wastewater generated during washing flows downwards in parallel in the plurality of hot wastewater channels  185 . Meanwhile, the cold water is introduced into a cavity  194  of the housing  177  from the cold water inlet  192  and flows through outer walls of the plurality of heat exchange pipes  179  from the bottom up, and is then exported from the tepid water outlet  193 . In the meantime, the cold water exchanges heat with the hot wastewater flowing through the hot wastewater channels  185  of the heat exchange pipes  179 , and is heated up as preheated water to reduce energy consumption. 
         [0250]    As shown in  FIG. 47 , the heat exchange pipes  179  are formed by mutual nesting of two metal pipes, i.e., an external metal pipe  195  and an internal metal pipe  196 , the external metal pipe  195  and the internal metal pipe  196  maintain good thermal contact therebetween, and leave a micro-channel  197  for the wastewater or cold water to pass through. The micro-channel  197  is formed between the external metal pipe  195  and the internal metal pipe  196  by having small concave-convex structures on a surface of the internal metal pipe  196  through knurling or the like. Under normal conditions, no cold water or wastewater seeps out of the micro-channel  197  between the external metal pipe  195  and the internal metal pipe  196 . However, when one of the external metal pipe  195  and the internal metal pipe  196  is damaged to cause seepage of cold water or hot wastewater, the cold water or hot wastewater may flow out of the heat exchanger main body  167  through the micro-channel  197 , for example, flowing out of a gap  198  between the main body  167  and the wastewater collector  165  or a gap  199  ( FIG. 45 ) between the main body  167  and the wastewater connector  169 , to send an alarm. Certainly, the nested structure is optional, and the metal pipe  179  may be illustrated and described in the form of a single piece in the following drawings and description for the sake of simplicity. 
         [0251]    After operating for a period of time, it is inevitable that fouling is accumulated on the inner walls of the wastewater channels  185  and the baffle structure  186 , which affects efficiency of heat recovery. As the opening  172  and the drain hole  161  are located above the plurality of wastewater outlets  174  and cover all the wastewater outlets  174  in a horizontal direction, as shown in  FIG. 48 , the user can wash away the fouling only by using a straight pipe  202  to insert one end thereof into the wastewater channels  185  through the wastewater outlets  174  of the wastewater collector  165 , and connecting pressurized water from the other end of the straight pipe  202  (for example, the other end is directly communicated to the cold water source of the building). 
         [0252]      FIG. 49  illustrates a structure of baffles in a second embodiment of the flow divider according to the present invention.  FIG. 50  illustrates a state in which the baffles are installed in each heat exchange pipe separately. Baffles  211  include strips  214  of which surfaces forming a spiral diversion structure  213 , and leave gaps  215  (see  FIG. 50 ) between the baffles and the heat exchange pipes  179 . When hot wastewater flows through the hot wastewater channels  185 , part of the hot wastewater vertically passes through the gaps  215 , and the other part blocked by the spiral diversion structure  213  spirally passes through the hot wastewater channels  185 , and the two water flows interfere with each other such that the hot wastewater is fully mixed and effectively exchange heat with cold water flowing reversely outside the heat exchange pipes  179 . 
         [0253]    A filtration device (not shown) can be disposed in the cavity  173  of the wastewater collector  165  to reduce clogging. After operating for a period of time, it is inevitable that fouling is accumulated on the inner walls of the wastewater channels  185 , and thus affecting water drainage and heat recovery efficiency. The user only needs to remove the filtration device and the baffles  211  from the opening  172  of the wastewater collector  165  for cleaning. 
         [0254]    As shown in  FIG. 51 , to further improve the heat exchange efficiency of the fluid heat exchanger  160  according to the present invention, a flow diverter  250  with a plurality of through holes  252  is disposed in the cavity  194  of the housing  177 , and a plurality of annular channels each surrounding each of the heat exchange pipes  179  is formed in the cavity  194  of the housing  177 . Various thermal conductive baffle as stated above can be configured in the annular channels. 
         [0255]      FIG. 52  illustrates an eighteenth embodiment of a thermal conductive baffle according to the present invention. The baffle  221  is formed by a plurality of sheet-like objects  222 ,  223  and  226  ( FIGS. 53, 54 and 55 ) disposed up and down with gaps. The sheet-like objects  222  and  223  are spoilers, which are alternately disposed horizontally in the cavity  194 . 
         [0256]    The spoiler  222  ( FIG. 53 ) is disc-like, and has a plurality of through holes  2221  corresponding to the heat exchange pipes  179  for nesting the heat exchange pipes  179  and forms a central opening  2222  for cold water to flow through, wherein edge  2223  clings to an inner wall of the cavity  194 . The spoiler  223  ( FIG. 54 ) is also disc-like, and also has a plurality of through holes  2231  corresponding to the heat exchange pipes  179  for nesting the heat exchange pipes  179 , and an edge  2232  and the inner wall of the cavity  194  leave a gap therebetween to form an opening  224  on the periphery for the cold water to pass through. A gap  225  is formed between any two closest spoilers  222  and  223 , and the openings  2222  and  224  do not overlap each other in the main surface direction of the spoilers  222  or  223 . After entering the cavity  194  through the cold water inlet  192 , the cold water is blocked by the spoiler  222  to enter the gap  225  between the baffle plates/sheets  222  and  223  from the opening  2222 , and then the cold water flows from the center to the periphery, and flows upwards through the spoiler  223  and the opening  224 . The cold water is once again blocked by the spoiler  222  in the upper layer to flow from the periphery to the center, and flows upwards through the opening  2222  of spoiler  222 . The process is repeated until the cold water flows out from the tepid water outlet  193 . In the meantime, the cold water circuitously flows through the plurality of heat exchange pipes  179  and exchanges heat with the hot wastewater flowing reversely therein, and the spoilers  222  and  223  constantly change the flow direction of the cold water, to generate turbulence effects, which are helpful to improve the heat exchange efficiency. To further improve the efficiency, one or more heat transfer sheets  226  as shown in  FIG. 55  can optionally be added between the spoilers  222  and  223 . The heat transfer sheets  226  are made of metal and are disc-like, which have a plurality of through holes  2261  corresponding to the heat exchange pipes  179  for nesting and thermally contacting the heat exchange pipes  179  and form a central opening  2262  for cold water to pass through, and an edge  2263  and the inner wall of the cavity  194  leave a gap therebetween to form an opening  227  at the periphery for cold water to pass through. When passing through the gap  225  between any two closest spoilers  222  and  223 , the cold water flows through two main surfaces of the heat transfer sheets  226  in parallel, and exchanges heat with hot wastewater in the pipes by means of the heat transfer sheets  226  and the plurality of heat exchange pipes  179  in good thermal contact therewith. The heat transfer sheets  226  significantly increase the heat exchange surface of the cold water, thereby improving the efficiency of the heat exchanger  165 . To further increase the heat exchange surface of the cold water, the spoilers  222  and  223  can also optionally be made of metal and thermally contact the plurality of metal pipes  179 . 
         [0257]      FIGS. 56-57  illustrate a structure of a nineteenth embodiment of a thermal conductive baffle according to the present invention. The baffle  231  is similar to the baffle  221  in the eighteenth embodiment, and their difference merely lies in that a net-like flow restrictor  232  is disposed between two adjacent parallel sheet-like objects  222 ,  223  or  226  of the baffle  231 , where the net-like flow restrictor  232  is also disc-like and is made by blanking a metal mesh as shown in  FIG. 25  The net-like flow restrictor  232  has a plurality of through holes  2323  corresponding to the heat exchange pipes  179  for nesting and thermally contacting the heat exchange pipes  179 . The manner in which the cold water passes through the baffle  231  is substantially the same as that in which the cold water passes through the baffle  221 , but if the cold water encounters the net-like flow restrictor  232  when passing through a fluid channel formed by two adjacent parallel sheet-like objects  222 ,  223  or  226  and the plurality of heat exchange pipes  179 , the cold water may flow through gaps between the metal wires  2321  and  2322 . Thus, the heat exchange surface of the cold water can be increased and further generate turbulence effects, which are helpful to improve the heat exchange efficiency. 
         [0258]      FIGS. 58-61  illustrate a structure of a twentieth embodiment of a thermal conductive baffle according to the present invention. The baffle  241  is similar to the baffle  221  in the fifteenth embodiment, and their difference merely lies in that a plurality of parallel grooves  2423 ,  2432  and  2443  are disposed on upper and lower surfaces of sheet-like objects  242 ,  243  and  244  of the baffle  241  respectively. Similarly, the spoiler  242  includes a plurality of through holes  2421  corresponding to the heat exchange pipes  179  for nesting and thermally contacting the heat exchange pipes  179  and a central opening  2422 ; the spoiler  243  also has a plurality of through holes  2431  corresponding to the heat exchange pipes  179  for nesting the heat exchange pipes  179 ; the heat transfer sheet  224  includes a plurality of through holes  2441  corresponding to the heat exchange pipes  179  for nesting and thermally contacting the heat exchange pipes  179  and also a central opening  2442 . The groove  2243  of the heat transfer sheet  224  increases the heat exchange surface of the cold water, and the grooves of the baffle sheet like objects  242 ,  243  and  244  constantly change the flow direction of the cold water, to further generate turbulence effects, which are helpful to improve the heat exchange efficiency. To further increase the heat exchange efficiency, the spoliers  242  and  243  can optionally be made of metal and thermally contact the plurality of heat exchange pipes  179 . 
         [0259]      FIGS. 62-63  illustrate a structure of a twenty-first embodiment of a thermal conductive baffle according to the present invention. The baffle  251  is formed by superposition of a plurality of net-like flow restrictor  232 . The specific structure of the net-like flow restrictor  232  has been described previously, which is not repeated herein. 
         [0260]      FIGS. 64-66  illustrate a structure of a twenty-second embodiment of the thermal conductive baffle according to the present invention. The baffle  261  is formed by superposition of a plurality of net-like flow restrictor  262 . The net-like flow restrictor  262  is made by blanking a metal mesh as shown in  FIG. 25 . The net-like flow restrictor  262  have a plurality of through holes  2623  corresponding to the heat exchange pipes  179  for nesting and thermally contacting the heat exchange pipes  179 . The net-like flow restrictor  262  are constructed to form rings having substantially the same width with the through holes  2623  as centers, and further form a central hole  2624  in the center of the net-like flow restrictor  262 . Correspondingly, shapes coupled to the rings are formed on the inner wall  264  of the cavity  194 , such that the baffle  261  clings to the inner wall of the cavity when being assembled into the cavity  194 . In addition, a center rod  263  can be inserted into the central hole  2624  of the baffle  261  to prevent the cold water from flowing through the central hole. Distances between portion of the baffle  261  for the cold water to flow through and the heat exchange pipe are substantially uniform, thus avoid the situation where heat exchange of the cold water in different portion of the baffle  261  is non-uniform. 
         [0261]      FIGS. 67-68  illustrate a structure of a twenty-third embodiment of the baffle having a thermal conductive baffle according to the present invention. The baffle  271  is formed by superposition of a plurality of net-like spoilers  272 , where the structure of the net-like spoilers  272  is basically similar to that of the net-like spoilers  232  in the seventeenth embodiment, and their difference merely lies in that, in the net-like spoilers  272 , metal wires in other peripheral parts  2721  and a central part  2723  are flattened except the rings having substantially the same width center to the through holes  2722  to close meshes and prevent the cold water from flowing there through. Therefore, distances between parts of the baffle  271  for the cold water to flow through and the heat exchange pipe are substantially uniform, and thus avoid the situation where heat exchange of the cold water in different parts of the baffle  271  is non-uniform. 
         [0262]      FIGS. 69-71  illustrate a fourth embodiment of the heat exchanger according to the present invention. The heat exchanger  280  is detachably disposed in a drain hole  295  of a bathroom floor drain device  283 . The heat exchanger  280  has a wastewater collector opening  291 , a wastewater collector cavity  292  and a plurality of wastewater collector outlets  293 . Hot wastewater generated after shower enters the wastewater collector opening  291  and flows into the wastewater collector cavity  292  from the drain hole  295 , then passes through the heat exchanger  280  in parallel in a plurality of wastewater channels  298  formed in a plurality of heat exchange pipes  296 , and is further discharged to a drain pipe (not shown) of the building through a drain port  299  of the drain device  283 . 
         [0263]      FIGS. 70-72  illustrate an assembly structure of the heat exchanger  280 . The heat exchanger  280  includes a main body  301  and a leakproof shell  302 . As shown in  FIG. 72 , cold water is introduced from a cold water inlet  303 , passes through a cavity  304 , and then is exported from a tepid water outlet  305 . In the meantime, the cold water exchanges heat with hot wastewater passing through the wastewater channels  298  through the plurality of heat exchange pipes  296 . Any one of the foregoing thermal conductive baffle can be disposed in the cavity  304  to increase the heat exchange efficiency. 
         [0264]    As shown in  FIGS. 73 and 74 , the heat exchange pipes  296  are formed by mutual nesting of two metal pipes, i.e., an internal metal pipe  306  and an external metal pipe  307 , where a bottom outer wall of the internal metal pipe  306  is in a sealed connection with the leakproof shell  302 , and the bottom of an outer wall of the external metal pipe  307  is in a sealed connection with a bottom shell  308  of the main body  301 . When there is leakage from the external metal pipe  307 , the cold water may flow into a cavity formed between an outer wall of the main body  301  and an inner wall of the leak proof shell  302  through a micro-channel  309  formed between the internal metal pipe  306  and the external metal pipe  307 , and then flows out from a leakage alarm hole  310  located above the heat exchange pipes  296  and in adjacent to a wastewater opening  301 . The user can notice the leakage in the bathroom and thus notify technicians for repair or replacement. 
         [0265]      FIGS. 75-76  illustrate a fifth embodiment of the heat exchanger according to the present invention. The heat exchanger  380  is installed to the bottom of a water catch  370 , and the water catch  370  has a platform  371 , a periphery  372  and a water catch outlet  375 . The water catch  370  is disposed on a shower room floor  378 . During operation, a person taking a shower stands on the platform  371 , and hot wastewater generated during shower is collected by the platform  371  and the periphery  372 , and flows out from the water catch outlet  375 . 
         [0266]      FIG. 77  illustrates a structure of the heat exchanger  380 , including a wastewater collector  381  and a heat exchanger main body  386 . The wastewater collector  381  has an opening  382 , a cavity  383  and a plurality of wastewater outlets  384 , where the opening  382  is located above the plurality of wastewater outlets  384 , and covers all the wastewater outlets  384  in a horizontal direction; the main body  386  includes a housing  387  and a plurality of metal pipes  391 , where the housing  387  has a cold water (second fluid) inlet  395 , a tepid water (preheated second fluid) outlet  396  and a cold water conduit  390  between the cold water inlet  395  and the tepid water outlet  396 ; the plurality of metal pipes  391  are disposed in the cold water conduit  390  of which the plurality of metal pipes  391  passes through the housing  387  and forms, in the cold water conduit  390 , a plurality of wastewater (first fluid) channels  392  for the hot wastewater to pass through in parallel. The plurality of wastewater channels  392  communicates with the plurality of wastewater outlets  384  of the wastewater collector  381  respectively. Wastewater, after flowing out from the water collector catch  375 , enters the cavity  383  through the opening  382  of the wastewater collector  381 , then passes through the plurality of wastewater channels  392  in parallel, and finally flows from a gap  376  ( FIG. 75 ) to a bathroom drain port  377  in the bottom of the water catch  370 . 
         [0267]    In use of the heat exchanger  380 , the cold water inlet  395  is directly or indirectly connected to a cold water source (not shown) of the building, and the tepid water outlet  396  is connected to a bathroom heater (not shown) or a mixing valve (not shown). 
         [0268]    In the meantime, the cold water is introduced from the cold water inlet  395  to flow through a cold water channel  400  from right to left, and exchanges heat with hot wastewater flowing through the hot wastewater channels  392  by means of the metal pipes  391 , such that the temperature of the cold water is changed and the cold water becomes preheated water, and then is exported from the tepid water outlet  396  and provided to the bathroom heater or the mixing valve (not shown) for use. 
         [0269]    As shown in  FIG. 77 , waste water channels  392  is flat, and has a major axis and a minor axis, where its centerlines are basically arranged horizontally, and the major axis is also arranged horizontally. The vertical height (minor axis) is designed so that wastewater flowing therein is in contact with both its upper and lower surfaces. In one example, when a vertical height (minor axis) of the wastewater channel  392  is less than 6.5 mm, even if the wastewater is flowing at an extremely low flow rate or even is almost stationary, due to resistance of the pipe wall and surface tension of the water, the wastewater passing through may still simultaneously contact two surfaces on the top and in the bottom of the waste water channel  392 . This ensures that the hot wastewater still has a sufficient heat exchange surface even if at a low flow rate. 
         [0270]    Optionally, the metal pipes  391  as shown in  FIG. 77  may be formed by mutual nesting of an internal metal pipe and an external metal pipe as illustrated in the third embodiment ( FIG. 48 ). The internal and external metal pipes maintain good thermal contact therebetween, and leave a micro-channel for the cold water to pass through. Under normal conditions, no cold water flows through the micro-channel  394 ; however, when the external metal pipe is damaged, the cold water may enter the leak proof shell  398  through the micro-channel  394 , and flow out from an alarm hole  401  ( FIG. 77 ), located above the metal pipes  391 , of the water catch  370  through a connecting pipe  399  ( FIG. 76 ) to alert the user. 
         [0271]    After operating for a period of time, it is inevitable that fouling is accumulated on the inner walls of the wastewater channels  392 , which affects efficiency of heat recovery. As the opening  382  of the collector covers all the wastewater outlets  384  in a horizontal direction, the user can wash away the fouling by removing a baffle plate  502  and insert straight pipe  202  connecting pressurized water (For example, the other end is directly communicated to the cold water feed of the shower) as shown in the third embodiment ( FIG. 9 ) into the wastewater outlets  384 . 
         [0272]    As shown in  FIG. 78 , a protruding baffle structure  402  may be formed on the inner walls of the wastewater channels  392  to improve the heat exchange efficiency, whereas the function and manufacturing method are substantially the same as those of the baffle structure shown in  FIG. 38 , and hence are not repeated herein. 
         [0273]    To further improve the efficiency of the heat exchanger  386 , various described a thermal conductive baffle can be added to the cold water cavity  400 , which is not repeated herein. 
         [0274]    An energy recovery device of the present invention including various heat exchangers stated above is described below. 
         [0275]    The energy recovery device further includes an external temperature-varying apparatus (not shown), where cold clean water (second fluid) after heat exchanged in the heat exchanger is introduced into the external temperature-varying apparatus, such that the temperature of the second fluid is changed to a suitable operating temperature, and the second fluid, after use, serves as hot wastewater (first fluid) introduced into the heat exchanger. 
         [0276]    The external temperature-varying apparatus includes a heater or a cooler (not shown). The external temperature-varying apparatus includes a fluid mixer for mixing the cold water (second fluid) after heat exchanged with an external preheated or pre-cooled third fluid to change the temperature. 
         [0277]    The heat exchanger can be installed to the bottom of a bathtub or a sink of a washing facility or a base of a shower, or is integrally formed with the base of the shower or the sink, to receive hot wastewater generated in shower or washing.