Abstract:
The present invention relates to a combustion apparatus having an intake air/exhaust air heat exchanger. The combustion apparatus comprises: a burner for generating exhaust gas; a blower for supplying external air to the burner; a main heat exchanger for absorbing heat from the exhaust gas generated by the burner; an exhaust gas duct for discharging the exhaust gas having passed the main heat exchanger to the outside; an intake air duct for introducing external air to the blower; an intake air/exhaust air heat exchanger for exchanging heat between the external air introduced to the blower and the exhaust gas discharged through the exhaust gas duct using a thin film plate disposed therebetween; and an exhaust flue for discharging the exhaust gas having passed the intake air/exhaust air heat exchanger to the outside.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of International Application No. PCT/KR2014/000177 filed on Jan. 8, 2014, which claims priority to Korean Application No. 10-2013-0020591 filed on Feb. 26, 2013. The applications are incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to a combustion apparatus having an intake air/exhaust air heat exchanger, and more particularly, to a combustion apparatus having an intake air/exhaust air heat exchanger, in which heat exchange is performed between exhaust gas generated from a burner and exhausted to the outside and intake air flowing from the outside. 
       BACKGROUND ART 
       [0003]    In general, a combustion apparatus is to heat water using combustion heat that is generated in a combustion process of fuel and circulate the heated water along a pipe so that the circulated water is used to heat a room or supply heated water, and includes a water heater and a boiler. 
         [0004]    Such a combustion apparatus includes a burner that combusts fuel gas to generate high-temperature thermal energy, a combustion chamber in which combustion of a mixture of air and gas is performed by the flame generated from the burner, a heat exchanger in which heat exchange is performed between exhaust gas having passed through the combustion chamber and water having passed through the inside of the pipe, and an exhaust gas duct that discharges, to the outside, the exhaust gas in which heat exchange has been performed in the heat exchanger, and an exhaust flue for discharging the exhaust gas to the outside of a building is connected to the exhaust gas duct. 
         [0005]    Since the exhaust gas discharged to the outside through the exhaust flue is high-temperature gas, the exhaust flue is made of aluminum or stainless steel as a heat-resistant metal material, so that there is a problem that manufacturing costs increase. 
         [0006]    In case of some countries, when the temperature of the exhaust gas discharged through the exhaust flue is low, the exhaust flue is allowed to be made of an inexpensive synthetic resin material, but the exhaust gas having passed through the heat exchanger is high temperature gas, so that the exhaust flue is difficult to be made of the synthetic resin material. 
         [0007]    Meanwhile, the exhaust gas exhausted to the outside through the exhaust flue contains high-temperature heat, and therefore thermal energy loss may occur when the exhaust gas is discharged to the outside as is. As the prior art for solving the above-described problem, Korean Patent Publication No. 10-2007-0032866 has been disclosed. 
         [0008]    By the above-described prior art, heat exchange is performed between air flowing from the outside and exhaust gas discharged to the outside, so that thermal energy loss may be minimized. 
         [0009]    In this case, in order to perform heat exchange in the exhaust flue, the exhaust flue is required to be made of a metal material having superior thermal conductivity, but the exhaust flue made of the metal material is expensive so that there is an economic disadvantage. 
       SUMMARY 
       [0010]    The present invention is directed to providing a combustion apparatus having an intake air/exhaust air heat exchanger, which may prevent thermal energy loss by heating intake air using the waste heat of high-temperature exhaust gas having passed the heat exchanger, and improve the thermal efficiency according to the temperature rise of the intake air. 
         [0011]    The present invention is also directed to providing a combustion apparatus having an intake air/exhaust air heat exchanger, in which an exhaust flue may be made of a synthetic resin material by lowering the temperature of exhaust gas exhausted to the outside, and thereby may reduce the installation costs. 
         [0012]    One aspect of the present invention provides a combustion apparatus including: a burner that generates exhaust gas; a blower that supplies external air to the burner; a main heat exchanger that absorbs heat from the exhaust gas generated by the burner; an exhaust gas duct that discharges the exhaust gas having passed through the main heat exchanger to the outside; an intake air duct that introduces the external air to the blower; an intake air/exhaust air heat exchanger that exchanges heat between the external air introduced to the blower and the exhaust gas discharged through the exhaust gas duct using a thin film plate interposed therebetween; and an exhaust flue that discharges the exhaust gas having passed through the intake air/exhaust air heat exchanger to the outside. 
         [0013]    Here, the main heat exchanger may include a sensible heat exchanger that absorbs combustion sensible heat generated by the burner and a latent heat exchanger that absorbs latent heat of the exhaust gas having passed through the sensible heat exchanger. 
         [0014]    Also, the intake air/exhaust air heat exchanger may include a plurality of thin film plates, each being formed into a flat plate shape, a first spacer that is provided to separate the thin film plates from one another and forms an intake air passage connected to the intake air duct, and a second spacer that is alternately laminated and arranged with the first spacer while being connected to the exhaust gas duct to form an exhaust gas passage so that heat exchange is performed between the exhaust gas passage and the intake air passage. 
         [0015]    Also, a temperature sensor for measuring the temperature of the exhaust gas passing through the inside of the exhaust gas duct may be provided in the exhaust gas duct, and a control unit may control to stop the operation of the combustion apparatus when the temperature measured by the temperature sensor is a set temperature or higher. 
         [0016]    Also, each of the first spacer and the second spacer may be formed into a curved shape so that peaks and valleys are formed thereon, a thickness of each of the thin film plates and the first and second spacers may be 20 to 70 μm, and the thin film plates and the first and second spacers may be made of thermoplastic resin. 
         [0017]    Also, the exhaust gas may be introduced from an upper side of the exhaust gas passage and flow vertically downward, a distance between the thin film plates that form the intake air passage may be smaller than a distance between the thin film plates that form the exhaust gas passage, and the exhaust flue may be made of a synthetic resin material. 
         [0018]    Also, a condensed water discharge pipe for discharging condensed water may be connected to the outlet side exhaust gas duct connected to the exhaust gas passage. 
         [0019]    According to the combustion apparatus of the present invention, by heating intake air using the waste heat of exhaust gas exhausted to the outside, the efficiency of the combustion apparatus may be improved. 
         [0020]    Also, by manufacturing an intake air/exhaust air heat exchanger using a thin film, instead of manufacturing an existing heat exchanger formed of an expensive metal plate, the manufacturing costs may be reduced, the heat exchangers having various sizes may be manufactured, and the durability of the heat exchanger may be improved thanks to excellent chemical performances such as water resistance, salt resistance, chemical resistance, and the like. 
         [0021]    Also, by lowering the temperature of exhaust gas exhausted to the outside, the exhaust flue may be made of a synthetic resin material, and thereby may reduce the installation costs of the combustion apparatus. 
         [0022]    Also, by making the dropping direction of condensed water coincide with the flowing direction of exhaust gas, the heat exchange efficiency in the intake air/exhaust air heat exchanger may be improved. 
         [0023]    Also, by making the distance between thin film plates forming an intake air passage smaller than the distance between thin film plates forming an exhaust gas passage, the heat exchange area may be increased and thereby the efficiency may be improved. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0024]      FIG. 1  is a schematic cross-sectional view showing a combustion apparatus according to an embodiment of the present invention; 
           [0025]      FIG. 2  is a perspective view showing an intake air/exhaust air heat exchanger according to an embodiment of the present invention; 
           [0026]      FIG. 3  is a view showing an intake air/exhaust air heat exchanger according to another embodiment of the present invention; and 
           [0027]      FIG. 4  is a perspective view showing an intake air/exhaust air heat exchanger according to another embodiment of the present invention. 
       
    
    
     DESCRIPTION OF REFERENCE NUMERALS OF THE MAIN ELEMENTS IN DRAWINGS 
       [0000]    
       
         
           
               1 : combustion apparatus 
               100 : blower 
               110  and  110 - 1 : inlet side intake air ducts 
               120  and  120 - 1 : outlet side intake air ducts 
               200 : burner 
               300 : main heat exchanger 
               310 : sensible heat exchanger 
               320 : latent heat exchanger 
               410 : inlet side exhaust gas duct 
               420 : outlet side exhaust gas duct 
               430 : temperature sensor 
               440 : exhaust flue 
               500 ,  500 - 1 , and  500 - 2 : intake air/exhaust air heat exchangers 
               510 ,  510 - 1 ,  510 - 2 ,  511 ,  511 - 1 , and  511 - 2 : intake air passages 
               520 ,  520 - 1 ,  520 - 2 ,  521 ,  521 - 1 , and  521 - 2 : exhaust gas passages 
               530 ,  530 - 1 ,  530 - 2 ,  531 ,  531 - 1 ,  531 - 2 ,  532 ,  532 - 1 ,  532 - 2 ,  533 ,  533 - 1 , and  533 - 2 : thin film plates 
               541 ,  541 - 1 ,  541 - 2 ,  542 ,  542 - 1 ,  542 - 2 : first spacers 
               540 ,  540 - 1 ,  540 - 2 ,  542 ,  542 - 1 , and  542 - 2 : second spacers 
           
         
       
     
       DETAILED DESCRIPTION 
       [0046]    Hereinafter, configurations and operations of preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. 
         [0047]      FIG. 1  is a schematic cross-sectional view showing a combustion apparatus according to an embodiment of the present invention, and  FIG. 2  is a perspective view showing an intake air/exhaust air heat exchanger according to an embodiment of the present invention. 
         [0048]    The combustion apparatus  1  according to the present invention includes a burner  200  that combusts a mixture of air and gas to generate exhaust gas, a blower  100  that supplies external air to the burner  200 , a main heat exchanger  300  that absorbs heat from the exhaust gas generated by the burner  200 , exhaust gas ducts  410  and  420  that discharge the exhaust gas having passed through the main heat exchanger  300  to the outside, intake air ducts  110  and  120  that introduce the external air to the blower  100 , an intake air/exhaust air heat exchanger  500  that exchanges heat between the external air introduced to the blower  100  and the exhaust gas discharged through the exhaust gas ducts  410  and  420  using thin film plates  530 ,  531 ,  532 , and  533  interposed therebetween, and an exhaust flue  440  that discharges the exhaust gas having passed through the intake air/exhaust air heat exchanger  500  to the outside. 
         [0049]    The combustion apparatus  1  according to the present invention may be applied to a boiler that performs heating or a water heater that supplies heated water, or applied to a device that combines heating and supply of heated water. 
         [0050]    The main heat exchanger  300  includes a sensible heat exchanger  310  that absorbs combustion sensible heat generated by the burner  200  and a latent heat exchanger  320  that absorbs latent heat of the exhaust gas having passed through the sensible heat exchanger  320 . 
         [0051]    In the latent heat exchanger  320 , condensed water is generated due to the absorption of the latent heat of the exhaust gas, and the generated condensed water is discharged through a condensed water discharge port  610 . A water trap (not shown) having a siphon structure to ensure that the water trap is kept in a state of being filled with the condensed water at a predetermined water level or more is connected to the condensed water discharge port  610 , so that the exhaust gas is prevented from being introduced into the room through the condensed water discharge port  610  during the operation of the boiler. 
         [0052]    The intake air/exhaust air heat exchanger  500  is provided at a point in which the intake air ducts  110  and  120  and the exhaust gas ducts  410  and  420  cross each other, so that heat exchange between the intake air and the exhaust gas is performed. 
         [0053]    The intake air ducts  110  and  120  includes the inlet side intake air duct  110  that supplies the intake air introduced from the outside to the intake air/exhaust air heat exchanger  500 , and the outlet side intake air duct  120  that is provided between the intake air/exhaust air heat exchanger  500  and the blower  100  so that the intake air that has been heated while passing through the intake air/exhaust air heat exchanger  500  is supplied to the blower  100 . 
         [0054]    An intake port  111  is connected to the inlet side intake air duct  110 , and an intake flue (not shown) for the inflow of external air is provided in the intake port  111 . 
         [0055]    In the present embodiment, a case in which the outlet side intake air duct  120  is connected to the blower  100  has been described, but a case in which there is no outlet side intake air duct  120  is possible. In this case, the intake air having passed through the intake air/exhaust air heat exchanger  500  is discharged to the interior space of the combustion apparatus  1 , and when the blower  100  is operated, air in the interior space of the combustion apparatus  1  is introduced into the blower  100 . 
         [0056]    The exhaust gas ducts  410  and  420  includes the inlet side exhaust gas duct  410  that allows the exhaust gas having passed through the main heat exchanger  300  to be introduced into the intake air/exhaust air heat exchanger  500 , and the outlet side exhaust gas duct  420  that allows the exhaust gas that has been cooled by heat exchange performed between the exhaust gas and the intake air to be discharged to the outside. 
         [0057]    An exhaust port  421  is connected to the outlet side exhaust gas duct  420 , and the exhaust flue  440  that is connected to the outside of a building in order to discharge the exhaust gas to the outside is connected to the exhaust port  421 . 
         [0058]    The exhaust gas is discharged to the outside in a state in which the temperature of the exhaust gas is lowered by heat exchange performed between the intake air and the exhaust gas while passing through the intake air/exhaust air heat exchanger  500 , and therefore the exhaust flue  440  may be made of a synthetic resin material. When the exhaust flue  440  is made of the synthetic resin material, it is possible to reduce the manufacturing costs of the combustion apparatus  1 . 
         [0059]    In the inlet side exhaust gas duct  410 , a temperature sensor  430  for measuring the temperature of the exhaust gas passing through the inside of the inlet side exhaust gas duct  410  is provided. When the temperature measured by the temperature sensor  430  is a temperature set in a control unit (not shown) or higher, the control unit controls to stop the operation of the combustion apparatus  1  in order to protect the intake air/exhaust air heat exchanger  500  constituted of thin films. 
         [0060]    In the present embodiment, a case in which the temperature sensor  430  is provided in the inlet side exhaust gas duct  410  has been described, but a case in which the temperature sensor  430  is provided in the outlet side exhaust gas duct  420  is possible. In this case, whether there is a need to protect the intake air/exhaust air heat exchanger  500  constituted of the thin films from the temperature of the exhaust gas passing through the inside of the outlet side exhaust gas duct  420  may be determined 
         [0061]    The intake air/exhaust air heat exchanger  500  includes the plurality of thin film plates  530 ,  531 ,  532 , and  533 , each being formed into a flat plate shape, first spacers  541  and  543  which are provided to separate the thin film plates  530 ,  531 ,  532 , and  533  from one another and form intake air passages  510  and  511  connected to the intake air ducts  110  and  120 , and second spacers  540  and  542  which are alternately laminated and arranged with the first spacers  541  and  543  while being connected to the exhaust gas ducts  410  and  420  to form exhaust gas passages  520  and  521  so that heat exchange is performed between the exhaust gas passages  520  and  521  and the intake air passages  510  and  511 . 
         [0062]    Each of the thin film plates  530 ,  531 ,  532 , and  533 , the first spacers  541  and  543 , and the second spacers  540  and  542  may be formed of a significantly thin film, and it is preferable that the thickness of the film be in a range of approximately 20 to 70 μm in consideration of the heat transfer coefficient. 
         [0063]    When the thickness of the film is relatively large, the heat transfer efficiency between the exhaust gas and the intake air is reduced, so that the exhaust gas is discharged in a state in which the temperature of the exhaust gas is relatively high and the intake air is introduced in a state in which the temperature of the intake air is relatively low, and therefore the outlet side exhaust gas duct  420  is difficult to be made of the synthetic resin material, which leads to an increase in the costs. In addition, the temperature of the mixture of air and gas introduced into the burner  200  cannot be raised, so that the efficiency is reduced and an amount of thermal energy that is wasted as waste heat is increased, which leads to a reduction in the efficiency. 
         [0064]    Each of the first spacers  541  and  543  and the second spacers  540  and  542  is formed into a curved shape so that peaks and valleys are formed thereon, and they serve to support the thin film plates  530 ,  531 ,  532 , and  533  in such a manner that the neighboring thin film plates  530 ,  531 ,  532 , and  533  are spaced apart from one another by a predetermined interval. 
         [0065]    The thin film plates  530 ,  531 ,  532 , and  533 , the first spacers  541  and  543 , and the second spacers  540  and  542  are made of thermoplastic resin such as polypropylene. In this case, the thermal conductivity of the material itself is not significantly high, but the thermal conductivity may be improved by reducing the thickness. 
         [0066]    By the above-described configuration, the intake air/exhaust air heat exchanger  500  is provided to absorb the waste heat of the exhaust gas so that the energy efficiency may be increased, and the intake air is heated using the exhaust gas and then supplied to the burner  200  so that the combustion efficiency may be improved. In addition, the exhaust gas is discharged to the outside after the temperature of the exhaust gas has dropped in the intake air/exhaust air heat exchanger  500 , and therefore the installation costs of the combustion apparatus  1  may be reduced when the outlet side exhaust gas duct  420  is made of a synthetic resin material. 
         [0067]    In addition, the intake air/exhaust air heat exchanger  500  may be manufactured using the thin film, and therefore heat exchangers having various sizes may be manufactured, and the durability of the heat exchanger may be improved thanks to excellent chemical performances such as water resistance, salt resistance, chemical resistance, and the like. 
         [0068]      FIG. 3  is a view showing an intake air/exhaust air heat exchanger according to another embodiment of the present invention. Here,  FIG. 3(   a ) shows a state in which an intake air duct and an exhaust gas duct are coupled to the intake air/exhaust air heat exchanger, and  FIG. 3(   b ) shows a cross-sectional structure of the intake air/exhaust air heat exchanger. 
         [0069]    Referring to  FIG. 3(   a ), in an intake air/exhaust air heat exchanger  500 - 1 , an inlet side intake air duct  110 - 1  through which external air is introduced and an outlet side intake air duct  120 - 1  for supplying the external air having passed through the intake air/exhaust air heat exchanger  500 - 1  to the blower  100  side are provided. In addition, in the intake air/exhaust air heat exchanger  500 - 1 , an inlet side exhaust gas duct  410 - 1  through which exhaust gas on which heat exchange has been performed in the main heat exchanger  300  passes and an outlet side exhaust gas duct  420 - 1  for discharging, to the outside, the exhaust gas on which heat exchange with the intake air has been performed are provided. 
         [0070]    Referring to  FIG. 3(   b ), the intake air/exhaust air heat exchanger  500 - 1  includes a plurality of thin film plates  530 - 1 ,  531 - 1 , and  532 - 1 , first spacers  541 - 1  and  543 - 1  which are provided to separate the thin film plates  530 - 1 ,  531 - 1 , and  532 - 1  from one another and form intake air passages  510 - 1  and  511 - 1  connected to the intake air ducts  110 - 1  and  120 - 1 , and second spacers  540 - 1  and  542 - 1  which are alternately laminated and arranged with the first spacers  541 - 1  and  543 - 1  while being connected to the exhaust gas ducts  410 - 1  and  420 - 1  to form exhaust gas passages  520 - 1  and  521 - 1  so that heat exchange is performed between the exhaust gas passages  520 - 1  and  521 - 1  and the intake air passages  510 - 1  and  511 - 1 . 
         [0071]    Here, the inlet side exhaust gas duct  410 - 1  is connected to an upper side of the intake air/exhaust air heat exchanger  500 - 1 , and the outlet side exhaust gas duct  420 - 1  is connected to a lower side of the intake air/exhaust air heat exchanger  500 - 1 . When connection is achieved in this manner, the exhaust gas is introduced from upper sides of the exhaust gas passages  520 - 1  and  521 - 1  inside the intake air/exhaust air heat exchanger  500 - 1  and flows vertically downward. 
         [0072]    As shown in  FIG. 2 , when the exhaust gas passages  520  and  521  are disposed in the horizontal direction, condensed water generated in the intake air/exhaust air heat exchanger  500  is brought into contact with the exhaust gas flowing in the horizontal direction while the condensed water drops within the exhaust gas passages  520  and  521 , and thereby may reduce the heat exchange efficiency. 
         [0073]    In the case of the embodiment of  FIG. 3 , by making the dropping direction of the condensed water coincide with the flowing direction of the exhaust gas, a reduction in the heat exchange efficiency in the intake air/exhaust air heat exchanger  500 - 1  may be prevented. 
         [0074]    Meanwhile, the condensed water may be generated in the exhaust gas passages  520 - 1  and  521 - 1  of the intake air/exhaust air heat exchanger  500 - 1 , and the generated condensed water may be discharged through a condensed water discharge pipe  450 - 1  connected to the outlet side exhaust gas duct  420 - 1 . The condensed water discharge pipe  450 - 1  is connected to the above-described water trap, so that the exhaust gas is discharged through the exhaust flue without being discharged to the room through the condensed water discharge pipe  450 - 1 . 
         [0075]      FIG. 4  is a perspective view showing an intake air/exhaust air heat exchanger according to another embodiment of the present invention. 
         [0076]    An intake air/exhaust air heat exchanger  500 - 2  includes a plurality of thin film plates  530 - 2 ,  531 - 2 ,  532 - 2 , and  533 - 2 , first spacers  541 - 2  and  543 - 2  which are provided to separate the thin film plates  530 - 2 ,  531 - 2 ,  532 - 2 , and  533 - 2  from one another and form intake air passages  510 - 2  and  511 - 2  connected to intake air ducts, and second spacers  540 - 2  and  542 - 2  which are alternately laminated and arranged with the first spacers  541 - 2  and  543 - 2  while being connected to exhaust gas ducts to form exhaust gas passages  520 - 2  and  521 - 2  so that heat exchange is performed between the exhaust gas passages  520 - 1  and  521 - 1  and the intake air passages  510 - 2  and  511 - 2 . 
         [0077]    Condensed water may be generated in the exhaust gas passages  520 - 2  and  521 - 2 , and it is preferable that a distance h 1  between the thin film plates  530 - 2  to  531 - 2  and  532 - 2  to  533 - 2  forming the exhaust gas passages  520 - 2  and  521 - 2  be maintained at such a distance that the condensed water can be smoothly discharged. 
         [0078]    In contrast, only air flows in the intake air passages  510 - 2  and  511 - 2 , and therefore the distance h 1  between the thin film plates  532 - 2  and  533 - 2  forming the intake air passages  510 - 2  and  511 - 2  may be smaller than a distance h 2  between the thin film plates  531 - 2  and  532 - 2  forming the exhaust gas passages  520 - 2  and  521 - 2 . 
         [0079]    In this manner, when the distance h 1  between the thin film plates  532 - 2  and  533 - 2  forming the intake air passages  510 - 2  and  511 - 2  is made smaller, an area in which heat exchange is performed is increased together with an increase in the number of the intake air passages  510 - 2  and  511 - 2  and the exhaust gas passages  520 - 2  and  521 - 2  within the intake air/exhaust air heat exchanger  500 - 2  having the same size, thereby improving the efficiency. 
         [0080]    While the invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.