Patent Publication Number: US-2010126500-A1

Title: Heat collector

Description:
TECHNICAL FIELD 
     The present invention relates to a heat collecting system, and more particularly, to a heat collector capable of efficiently absorbing external heat. 
     BACKGROUND ART 
       FIG. 1  is a schematic view illustrating a general heat collecting system using a tube type heat collector. As shown in the drawing, a heat collecting system  2  includes a heat collector  4  to convert working fluid introduced thereinto through a water supply pipe P into working fluid of high temperature, a heat accumulator  6  to store the working fluid of high temperature, and a pump  8  to supply the working fluid to the heat accumulator  6  from the heat collector  4 . 
     As shown in  FIG. 2 , the heat collector  4  includes a heat collecting part  10  through which the working fluid flows, and a heat insulating part  12  which surrounds the heat collecting part  10  and is filled with a heat insulating gas. The working fluid serves to transfer a thermal energy absorbed from incident light to the heat accumulator  6 . Water is commonly used as the working fluid, however the working fluid is not limited to water. In order to prevent the working fluid from being frozen in winter, an antifreezing solution or a mixture of an antifreezing solution and water by a predetermined ratio may be used as the working fluid. 
     The heat accumulator  6  serves to store the thermal energy contained in the working fluid, and is designed so as to minimize heat loss to the outside. 
    
    
     The operation of the above-described conventional heat collecting system will now be explained. 
     The working fluid, which serves as a heat transfer medium, is introduced into the heat collector  4 , and the working fluid in the heat collector absorbs solar heat and is converted into working fluid of high temperature. After such a heat collecting process, the working fluid of high temperature is discharged from the heat collector  4 , and then flows into the heat accumulator  6  by the pump  8 . The thermal energy stored in the heat accumulator  6  is used for heating or warm water as needed. 
     DISCLOSURE OF INVENTION 
     Technical Problem 
     However, the conventional heat collector has a problem such that it cannot effectively collect heat. Such a problem is resulted from that the heat collecting structure is not a structure effective for heat collection. 
     Also, the heat insulating part of the heat collector does not have a structure sufficient for effective heat insulation for the heat collecting part. 
     An object of the present invention is to provide a heat collector capable of more effectively collecting heat. 
     Technical Solution 
     The objects of the present invention can be achieved by providing a heat collector comprising: a heat collecting part to receive external heat while working fluid as a heat transfer medium flows through the heat collecting part; a heat insulating part provided to surround the heat collecting part so as to decrease heat loss of the heat collecting part; and a reflecting membrane formed in the heat insulating part so as to reflect and concentrate incident light onto the heat collecting part. 
     The reflecting membrane may be formed to be rounded, centering on the heat collecting part. 
     The reflecting membrane may be made of a material capable of reflecting the incident light to the heat collecting part so that the incident light is concentrated on the heat collecting part. 
     The reflecting membrane may be made of a flexible material. 
     The reflecting membrane may divide the heat insulating part into two spaces, and the two spaces may have pressures different from each other. 
     In another aspect of the present invention, provided herein is a heat collector comprising: a heat collecting part to receive external heat while working fluid as a heat transfer medium flows through the heat collecting part; and a heat insulating part filled with a heat insulating gas, the heat insulating part being defined by a heat insulating membrane provided to surround the heat collecting part, and the heat insulating membrane including an inner surface having a reflecting function so as to reflect and concentrate incident light onto the heat collecting part. 
     In another aspect of the present invention, provided herein is a heat collector comprising: a heat collecting part to receive external heat while working fluid as a heat transfer medium flows through the heat collecting part; a heat insulating part filled with a heat insulating gas, the heat insulating part surrounding the heat collecting part to decrease heat loss of the heat collecting part; and a vacuum part provided between the heat insulating part and the heat collecting part to wrap the heat collecting part, the vacuum part being formed so that a negative pressure is generated therein. 
     The vacuum part may be sectioned into a plurality of spaces. At this time, a plurality of partitions may be used to divide the vacuum part. 
     The divided spaces may have the substantially same pressure. 
     The partitions may be formed with through-holes. 
     The heat collector may further comprise an air path to allow external air to be introduced or discharged into/from the vacuum part. 
     The vacuum part and the heat insulating part may have pressures different from each other. 
     In a further aspect of the present invention, provided herein is a heat collector comprising: a heat collecting part to receive external heat while working fluid as a heat transfer medium flows through the heat collecting part; a heat insulating part provided to surround the heat collecting part so as to decrease heat loss of the heat collecting part; a vacuum part provided between the heat insulating part and the heat collecting part to wrap the heat collecting part, the vacuum part being formed so that a negative pressure is generated therein; and a reflecting membrane formed in either the vacuum part or the heat insulating part to reflect and concentrate incident light onto the heat collecting part. 
     In yet another aspect of the present invention, provided herein is a heat collector comprising: a heat collecting part to receive external heat while working fluid as a heat transfer medium flows through the heat collecting part; a heat insulating part defined by a heat insulating membrane provided to surround the heat collecting part so as to decrease heat loss of the heat collecting part; and a vacuum part defined by a vacuum membrane provided between the heat insulating part and the heat collecting part to wrap the heat collecting part, the vacuum part being formed so that a negative pressure is generated therein. Either the heat insulating membrane or the vacuum membrane includes a surface which opposes the heat collecting part and has a reflecting function within a predetermined region thereof. 
     According to the heat collector of the present invention as constituted above, since the reflecting membrane is provided around the heat collecting part, incident light can be concentrated on the heat collecting part. Further, if the vacuum part is provided between the heat collecting part and the heat insulating part, heat radiation and loss from the heat collecting part can be decreased. 
     ADVANTAGEOUS EFFECTS 
     The heat collector according to the present invention as explained above has the following effects. 
     Since the reflecting membrane is positioned around the heat collecting part of the heat collector, the incident light can be concentrated on the heat collecting part. Accordingly, the higher heat collecting effect can be obtained. 
     Further, since the vacuum part is provided between the heat collecting part and the heat insulating part, the heat radiation from the heat collecting part to the outside can be decreased. 
     MODE FOR THE INVENTION 
     Hereinafter, a heat collector according to a first embodiment of the present invention will be described with reference to  FIG. 3 . 
     As shown in  FIG. 3 , a heat collector  20  according to the present invention includes a heat collecting part  23  which receives external heat while working fluid as a heat transfer medium flows therethrough, a heat insulating part  25  which is an inner space of a heat insulating membrane  24  mounted to surround the heat collecting part  23 , the heat insulating part  25  being filled with a heat insulating gas and serving to decrease heat loss of the heat collecting part  23 , and a reflecting membrane  26  which is formed in the heat insulating part  25  in order to reflect and concentrate incident light onto the heat collecting part  23 . 
     The heat insulating part  25  serves to decrease radiation of a thermal energy of the working fluid located in the heat collecting part  23  to the outside, and there is no limitation in the kind of heat insulating gas filled in the heat insulating part  25 . However, it is preferred that air, which is economical and easily available, is used as the heat insulating gas. 
     The heat collecting part  23  serves to receive external heat, and may be defined by a heat collecting membrane  22 . The heat insulating part  25  may be defined by the heat insulating membrane  24  in which the heat insulating gas can be filled. Solar light may be used as the incident light. 
     The heat insulating part  25  may be sectioned into a plurality of spaces by partitions  25   a.    FIG. 3  illustrates the heat collector having the three partitions  25   a  provided in the heat insulating part  25 . The partitions  25   a  serve to connect the heat collecting membrane  22  with the heat insulating membrane  24 , thereby preventing the heat collecting part  23  from severely sagging under the weight of the working fluid in the heat collecting part  23  in the gravity direction. 
     The partitions  25   a  are formed with a plurality of through-holes (not shown), so that two spaces of the heat insulating part  25 , which are divided by each of the partitions  25   a,  can have the same inner pressure as each other. 
     Preferably, the heat insulating membrane  24  and the partitions  25   a  are made of a transparent material so that the external light can pass therethrough. Also preferably, the heat collecting membrane  22  is made of a black material so as to increase light absorptiveness. 
     Further, the heat collecting membrane  22 , the heat insulating membrane  24  and the partitions  25   a  may be made of a flexible material. In other words, the heat collecting membrane  22 , the heat insulating membrane  24  and the partitions  25   a  may be made of a resin material, e.g., vinyl resin. When the flexible material such as vinyl resin is used, the heat collector  20  can be swollen by filling the heat insulating gas into the gas insulating part  25  sufficiently to make the pressure in the heat insulating part  25  larger than the atmospheric pressure, and the working fluid in the heat collecting part  23  can have an adequate pressure. Accordingly, the sectional shape adequate for heat collection can be realized as shown in  FIG. 3 . 
     The resin has merits of a low price and easy modification in various shapes. The heat collector can be formed in a shape adequate to receive solar light. The heat collector  20  can be installed in a broad place, such as a field, a farm, etc. Depending on the change of shape or installing position of the heat collector, even when the density of incident solar light is low, an excellent heat collecting effect can be obtained. 
     The heat collector  20  further includes the reflecting membrane  26  so that the light having passed through the heat insulating membrane  24  and the partitions  25   a  can be reflected to the heat collecting part  23 . The reflecting membrane  26  is provided in the heat insulating part  25 . The reflecting membrane reflects the incident light so that more incident light can enter the heat collecting part  23 . By virtue of the reflecting membrane, the better heat collecting effect can be obtained. 
     Also, as shown in  FIG. 3 , the reflecting membrane  26  may be formed in a thin film, and may be formed to be rounded, centering on the heat collecting part  23 , in an opposite portion to a portion receiving the incident light. The reflecting membrane  26  rounded centering on the heat collecting part  23  concentrates the light reflected therefrom onto the heat collecting part  23 . 
     The reflecting membrane  26  may be made of a reflective material so as to reflect the light. For example, a material such as mercury may be coated on one surface of the reflecting membrane  26  so that minor reflection can be achieved. The overall reflecting membrane  26  may be made of a reflective material, or only a portion of the reflecting membrane  26  may be made of a reflective material. 
     The reflecting membrane  26  may also be made of a flexible material. For example, the reflecting membrane is made of resin, to thereby improve workability. When the resin is used for the reflecting membrane, the reflecting surface may be plated with metal. 
     Also, as shown in  FIG. 3 , the heat collector may be constituted such that a pressure applied to the incident light receiving space of the heat insulating part  25  defined by the reflecting membrane  26  is different from a pressure applied to the space opposite to the incident light receiving space. For example, if the pressure of the incident light receiving space is set to be larger than the pressure of the opposite space, the reflecting membrane  26  is always kept in the expanded state as shown in the drawing, so as not to be contacted with the heat collecting membrane  22 . 
     Moreover, since the reflecting membrane  26  is always kept in the shape as shown in  FIG. 3 , the light can be reflected and concentrated onto the heat collecting part  23 . 
     In the above-described embodiment, the reflecting membrane  26  is separately provided. However, the reflecting membrane  26  may be eliminated, and the inner surface of the heat insulating membrane  24  may be formed to have a reflecting function so as to reflect the light incident near the heat collecting part  23  and concentrate the light on the heat collecting part  23 . The inner surface of the heat insulating membrane  24  may be designed to wholly or partially have the reflecting function as needed. 
     Hereinafter, the operation of the heat collector according to the first embodiment of the present invention will be explained. The working fluid flows along a path in the heat collecting membrane  22 . At this time, the external incident light transmits the heat insulating membrane  24 . A portion of the incident light is introduced into the heat collecting part  23 , and the remaining portion transmits the partitions  25   a.    
     The light having transmitted the partitions  25   a  reaches the reflecting membrane  26 . Then, the light is reflected from the reflecting membrane  26 , and is introduced into the heat collecting part  23 . At this time, since the reflecting membrane  26  is rounded centering on the heat collecting part  23 , the light reflected from the reflecting membrane  26  can be more concentrated on the heat collecting part  23 . 
     Next, a heat collector according to a second embodiment of the present invention will be described with reference to  FIG. 4 . 
     As shown in  FIG. 4 , a heat collector  30  according to the present invention includes a heat collecting part  33  which receives external heat while working fluid as a heat transfer medium flows therethrough, a heat insulating part  35  which is filled with a heat insulating gas and surrounds the heat collecting part  33  to decrease heat loss of the heat collecting part  33 , and a vacuum part  37  which is provided between the heat insulating part  35  and the heat collecting part  33  to wrap the heat collecting part  33  and in which a negative pressure is generated. 
     The heat collecting part  33  and the heat insulating part  35  may be constituted similar to the first embodiment shown in  FIG. 3 . The point different from the first embodiment is that the vacuum part  37  is additionally provided between the heat collecting part  33  and the heat insulating part  35 , which will be explained in detail hereinafter. 
     The vacuum part  37 , as shown in  FIG. 4 , is formed to perfectly wrap the heat collecting part  33 . A negative pressure, which is a pressure lower than the atmospheric pressure, is generated in the vacuum part. 
     If the vacuum part  37  has a negative pressure, heat convection and heat transfer in the vacuum part  37  are decreased, when compared to a positive pressure which is a pressure higher than the atmospheric pressure. That is, the heat in the heat collecting part  33  is blocked by the vacuum part  37 , and thus heat radiation to the outside is decreased. Accordingly, since heat loss from the heat collecting part  33  is reduced by the vacuum part  37 , thermal efficiency of the overall heat collector  30  is enhanced. 
     The vacuum part  37  may be provided with an air path (not shown), through which the interior of the vacuum part  37  communicates with the exterior. For example, the air path may be configured as a tube mounted to communicate the interior of the vacuum part  37  with the exterior. 
     A vacuum membrane  36  defining the vacuum part  37  is disposed at a predetermined gap from a heat collecting membrane  32  defining the heat collecting part  33 . That is, the vacuum part  37  can be formed by disposing the vacuum membrane  37  at a predetermined gap from the heat collecting membrane  32 , and the above-described effects can be achieved. 
     The vacuum part  37  may be provided with a plurality of partitions  36   a  therein, in order to divide the vacuum part  37 . The partitions  36   a  serve to connect the heat collecting membrane  32  with the vacuum membrane  36 , thereby preventing the heat collecting part  33  from severely sagging under the weight of the working fluid in the heat collecting part  33  in the gravity direction. 
     The air path may be provided at each of the spaces of the vacuum part  37 , which are divided by the partitions  36   a.  However, if the respective partitions  36   a  are formed with through-holes (not shown), all of the divided spaces of the vacuum part  37  have the same pressure. In such a case, only one air path may be provided at the vacuum part  37 . 
     A heat insulating membrane  34  is disposed at a predetermined gap from the vacuum membrane  36 . That is, an air layer can be formed in the air insulating part  35  by disposing the heat insulating membrane  34  at a predetermined gap from the vacuum membrane  36 , and the air layer serves as a heat insulating means. Accordingly, the heat in the heat collecting part  33  can be insulated. 
     The pressure in the heat insulating part  35  should be maintained over a predetermined value. More preferably, as shown in  FIG. 4 , the pressure in the heat insulating part  35  is set to be high enough to expand the heat insulating membrane  34  outside. By virtue of partitions  34   a  connected to the expanded heat insulating membrane  34 , the vacuum membrane  36  is not contacted with the heat collecting membrane  32  while keeping a predetermined gap with the heat collecting membrane  32 . 
     In order to make the spaces divided by the partitions  34   a  have the same pressure, the partitions  34   a  may be formed with through-holes (not shown), similar to the partitions of the vacuum part  37 . 
     Hereinafter, the operation of the heat collector according to the second embodiment of the present invention will be explained. The working fluid flows along a path in the heat collecting part  33 . At this time, the external incident light transmits the heat insulating membrane  34  and the vacuum membrane  36 , and is introduced into the heat collecting part  33 . 
     The light introduced into the heat collecting part  33  is used to heat the working fluid in the heat collecting part  33 . When the heat collecting part  33  is heated to have a temperature higher than an external temperature, the heat in the heat collecting part  33  may be radiated to the outside. 
     However, since the vacuum part  37  having a predetermined space is provided to wrap the heat collecting part  33 , the amount of heat radiated to the outside is reduced. Further, since a negative pressure is generated in the vacuum part  37 , the amount of air as a heat transfer medium is small, and thus heat conduction and heat convection do not occur much. Accordingly, the heat radiation from the heat collecting part  33  to the outside does not occur much, and as a result heat collecting efficiency is enhanced. 
     As shown in  FIG. 5 , a heat collector  40  according to a third embodiment of the present invention includes both a reflecting membrane  48  and a vacuum membrane  46 . 
     The heat collector  40  includes a heat collecting part  43  which receives external heat while working fluid as a heat transfer medium flows therethrough, a heat insulating part  45  which surrounds the heat collecting part  43  to decrease heat loss of the heat collecting part  43 , a vacuum part  47  which is provided between the heat insulating part  45  and the heat collecting part  43  to wrap the heat collecting part  43  and in which a negative pressure is generated, and a reflecting membrane  48  which is formed in either the vacuum part  47  or the heat insulating part  45  to reflect and concentrate the heat onto the heat collecting part  43 . 
     Instead of the reflecting membrane  48 , a surface of either the vacuum membrane  46  or the heat insulating membrane  44 , which opposes the heat collecting part, may be formed to have a reflecting function within a predetermined region of the surface, so as to concentrate the incident light on the heat collecting part  43 . 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. 
     INDUSTRIAL APPLICABILITY 
     The present invention relates to the heat collecting system, and more particularly, to the heat collector capable of effectively absorbing external heat. The heat collector according to the present invention has the reflecting surface. The reflecting surface reflects the incident light to the heat collecting part so that a larger amount of light is concentrated on the heat collecting part, thereby enhancing the heat collecting effect.