Backflow type solar air heat collector

Abstract

The invention belongs to the technical field of solar heating, and particularly relates to a backflow type solar air heat collector which comprises a first box body, a second box body, a heat-absorbing and air-sucking part is arranged on the top of the first box body, and other side walls of the first box body are arranged in a heat-insulating mode. The air inlet end of the air exhaust assembly is arranged at one end of the first box body in a communicating manner; the air inlet end of the four-way joint is communicated with the air outlet end of the air exhaust assembly, the third air outlet end of the four-way joint is communicated with a heat collector outlet through an adjustable valve, the first air outlet end and the second air outlet end of the four-way joint are respectively communicated with the air inlet end of an air return part, and the air outlet end of the air return part is arranged towards the air inlet end of the heat absorption and air suction part; the air inlet end of the air return part sucks air in the first box body and the air is sprayed out from the air outlet end of the air return part to form an air curtain. According to the device, high-speed jet flow is generated by pumping air from the interior of the device, an air curtain is formed on the surface of the heat absorption and air suction part, the heat insulation and heat preservation effects can be achieved, and meanwhile multiple times of cyclic heating of air can be achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of solar heating, and in particular relates to a reflow type solar air collector. Background Art

[0002] As a renewable energy source, solar energy can effectively alleviate the dependence on fossil energy. The world is facing severe challenges brought by climate change, and reducing greenhouse gas emissions has become a common goal of all countries.

[0003] As a clean and renewable energy technology, solar thermal collectors can help reduce greenhouse gas emissions and help address global energy issues. The use of solar thermal collectors can reduce the use of traditional energy sources such as coal and oil, reduce air pollution, improve environmental quality, and have a positive significance for preventing global warming. In recent years, the continuous innovation of photothermal materials and heat-absorbing coatings and the application of intelligent control technologies (such as flow monitoring and temperature control) have greatly improved the thermal efficiency of solar thermal collectors, improved the operating efficiency of collectors, and reduced the manufacturing and maintenance costs of solar thermal collection equipment.

[0004] Solar collectors can be divided into many types according to their structures and working principles, and each type of collector has its own unique advantages and disadvantages. Taking the traditional flat-plate collector and the infiltration air collector as examples, the flat-plate collector, due to structural reasons, has a glass cover that reflects part of the sunlight, reduces the heat absorption of the collector, and also has serious heat loss; the infiltration air collector has good thermal conductivity of metal, so in a cold environment or when not in use for a long time, the heat inside the collector is easily dissipated to the outside, resulting in large heat loss. Therefore, in order to improve the heat absorption efficiency, reduce heat loss, and at the same time increase or reach the outlet air temperature we need, a reflow solar air collector is proposed. Summary of the invention

[0005] The object of the present invention is to provide a reflow type solar air collector to solve the above problems.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] A reflow type solar air collector, comprising:

[0008] A first box body, wherein a heat absorbing and air absorbing portion is provided on the top of the first box body, and the remaining side walls of the first box body are heat-insulated;

[0009] An exhaust component, wherein the air inlet end of the exhaust component is connected to and arranged at one end of the first box body;

[0010] A four-way, wherein the air inlet end of the four-way is connected to the air outlet end of the exhaust assembly, the third air outlet end of the four-way is connected to the collector outlet through an adjustable valve, the first air outlet end and the second air outlet end of the four-way are respectively connected to the air inlet end of the air return part, and the air outlet end of the air return part is arranged toward the air inlet end of the heat absorption air intake part;

[0011] The air inlet end of the air return part sucks the air inside the first box body and sprays it out from the air outlet end of the air return part to form an air curtain.

[0012] Optionally, the heat absorption and air suction part comprises a porous metal plate, the porous metal plate is fixedly connected to the top of the first box body, and a plurality of air suction holes are opened on the porous metal plate.

[0013] Optionally, the bottom ends of a plurality of pillars are fixedly connected in the first box, the pillars are evenly arranged in the first box, and the top ends of the pillars are fixedly connected to the bottom of the porous metal plate.

[0014] Optionally, the exhaust assembly includes a tapered flow channel, the inlet end size of the tapered flow channel is larger than the outlet end size, the inlet end of the tapered flow channel is fixedly connected to and connected to one end of the first box body, and the outlet end of the tapered flow channel is connected to an exhaust part.

[0015] Optionally, the exhaust part includes a fan, the air inlet end of the fan is connected to the outlet end of the tapered flow channel through an air outlet pipe, and the air outlet end of the fan is connected to the air inlet end of the four-way.

[0016] Optionally, the air return section includes a second box body, two second box bodies are respectively fixed to the front and rear sides of the first box body, the top of the second box body is arranged higher than the top of the first box body, and a strip seam is opened on the top of the second box body toward the porous metal plate, and the side walls of the two second box bodies are respectively connected to the first air outlet end and the second air outlet end of the four-way.

[0017] Optionally, the first air outlet end and the second air outlet end of the four-way are respectively connected to the air inlet end of the return air duct, and the air outlet end of the return air duct is connected to the corresponding second box.

[0018] Optionally, a temperature sensor is provided at the collector outlet.

[0019] Optionally, the porous metal plate is a metal plate with a thickness of 2 mm.

[0020] Optionally, the porous metal plate is a copper plate or an aluminum plate.

[0021] Compared with the prior art, the present invention has the following advantages and technical effects:

[0022] When the device is working in the external environment, when the exhaust assembly is running, the air in the first box is transported to the air inlet end of the four-way, and under the action of air pressure, the air can be sucked into the first box through the heat-absorbing air intake part and heated at the same time, and the heated air is sent to the other three ports of the first air outlet end, the second air outlet end and the third air outlet end. When the adjustable valve is completely closed, the air is sent to the return air parts on both sides through the first air outlet end and the second air outlet end on both sides of the four-way, and its air outlet end faces the air inlet end of the heat-absorbing air intake part. The return air part is in the form of a jet, shooting towards the surface of the heat-absorbing air intake part, forming an air curtain on the outer surface of the porous metal plate. Since there is no cover plate on the upper part of the heat-absorbing air intake part, and there is often crosswind flowing through the external environment, it will take away the heat on the surface of the porous metal plate of the collector, thereby causing more serious heat loss. Part of the heated air in the form of a jet will diffuse upward to the atmosphere, and the rest of the air will be re-inhaled by the heat absorption and suction part, so that part of the heated air will enter the device again for the next heating cycle, and repeat in sequence, thereby playing the role of multiple heating; when the adjustable valve is partially opened, part of the air will be directly discharged from the collector outlet connected to the adjustable valve, and the remaining air will still enter the corresponding return air part through the first air outlet and the second air outlet after the four-way diversion, and continue to be ejected to the surface of the heat absorption and suction part in the form of a jet, so that it will be absorbed and heated again to participate in the next cycle, so that the size of the adjustable valve opening can control the amount of return air (also called air circulation ratio); when the adjustable valve is fully opened, affected by the resistance along the return air parts on both sides and the local resistance, the hot air will directly choose the collector outlet with the smallest resistance and the nearest adjustable valve to be discharged. Based on the needs of the actual application scenario, that is, based on the needs of the outlet air temperature, by monitoring the outlet temperature, the air in the circulating part is reduced when the temperature is high, and the air in the circulating part is increased when the temperature is low, and finally the temperature control is achieved. Compared with traditional technology, this device relies on high-speed jet air to form an air curtain wall on the surface of the heat absorption and air intake part, which not only prevents the heat of the porous metal plate from diffusing outward, but also isolates the interference of external crosswind on the collector, plays a role in heat preservation and heat insulation, and can effectively improve the thermal efficiency of the infiltration type air collector; compared with inhaling air from the external environment to form a side-delivery jet, another advantage of this device is that the gas source of the air curtain is the heated air, which realizes the second or even multiple heat exchange between the air and the porous metal plate, so that the outlet temperature is improved. This device can realize multiple cycles of air heating, thereby improving the air outlet temperature of the collector. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative labor:

[0024] Figure 1 It is a schematic diagram of the structure of the present invention;

[0025] Figure 2 It is a schematic diagram of the structure of the first box and the tapered flow channel of the present invention;

[0026] Figure 3 It is a schematic diagram of the structure of the four-way part of the present invention;

[0027] Among them, 1. porous metal plate; 2. air intake hole; 3. second box; 4. support; 5. return air duct; 6. tapered flow channel; 7. fan; 8. four-way; 9. adjustable valve; 10. collector outlet; 11. temperature sensor; 12. strip slit; 13. air outlet duct; 14. first box. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] Reference Figures 1 to 3 The present invention discloses a reflow type solar air collector, comprising:

[0031] A first box body 14, wherein a heat absorbing and air absorbing portion is disposed on the top of the first box body 14, and the remaining side walls of the first box body 14 are heat insulated;

[0032] An exhaust component, the air inlet end of the exhaust component is connected to one end of the first box body 14;

[0033] The air inlet end of the four-way 8 is connected with the air outlet end of the exhaust assembly, the third air outlet end of the four-way 8 is connected with the collector outlet 10 through an adjustable valve 9, the first air outlet end and the second air outlet end of the four-way 8 are respectively connected with the air inlet end of the return air part, and the air outlet end of the return air part is arranged toward the air inlet end of the heat absorption air intake part.

[0034] When the device is working in the external environment, when the exhaust assembly is running, the air in the first box 14 is transported to the air inlet end of the four-way 8. Under the action of air pressure, the air can be sucked into the first box 14 through the heat-absorbing air intake part and heated at the same time. The heated air is sent to the other three ports of the first air outlet end, the second air outlet end and the third air outlet end. When the adjustable valve 9 is completely closed, the air is sent to the return air parts on both sides through the first air outlet end and the second air outlet end on both sides of the four-way 8. The air outlet end faces the air inlet end of the heat-absorbing air intake part, and the return air part is in the form of a jet, shooting towards the surface of the heat-absorbing air intake part to form an air curtain. Since there is no cover plate on the upper part of the heat-absorbing air intake part, and there is often crosswind flowing through the external environment, it will take away the heat on the surface of the metal plate and interfere with the air flow on the upper part of the collector. Due to the heating effect of the metal plate, part of the heated air in the form of a jet will diffuse upward into the atmosphere, and the remaining air will be re-inhaled by the heat-absorbing air intake part, so that part of the heated air will re-enter the device for the next cycle, and repeat in sequence, thereby playing the role of multiple heating; when the adjustable valve 9 is partially opened, part of the air will be directly discharged from the collector outlet 10 connected to the adjustable valve 9, and the remaining air will still enter the corresponding return air part through the first air outlet end and the second air outlet end after being diverted by the four-way 8, and continue to be ejected to the surface of the heat-absorbing air intake part in the form of a jet, so that it will be absorbed and heated again to participate in the next cycle, so that the size of the opening of the adjustable valve 9 can control the amount of return air (also called the air circulation ratio); when the adjustable valve 9 is fully opened, affected by the resistance along the return air parts on both sides and the local resistance, the hot air will directly choose the collector outlet 10 with the smallest resistance and the closest adjustable valve 9 to be discharged. Compared with traditional technology, this device relies on high-speed jet air to form an air curtain wall on the surface of the heat absorption and air intake part, preventing hot air from diffusing outward, isolating from the interference of external crosswind, playing a role of heat insulation and heat preservation, and improving thermal efficiency; compared with the side-delivered jet air directly coming from the environment, another advantage of this device is that the gas source of the air curtain is the heated air, which realizes the second or even multiple heat exchange between the air and the porous metal plate, so that the outlet temperature is improved. This device can realize multiple cycles of air heating, thereby increasing the air outlet temperature of the collector.

[0035] As an optional embodiment, the air source for forming the jet air curtain may be air drawn from the external environment, which can simplify the composition of the entire system. However, it is preferred that the air is drawn from inside the system.

[0036] As an optional implementation, the heat absorption and air intake part comprises a porous metal plate 1 , which is fixed to the top of the first box body 14 , and a plurality of air intake holes 2 are formed on the porous metal plate 1 .

[0037] Compared with the glass cover, the porous metal plate 1 does not reflect sunlight, and can improve the efficiency of sunlight heat absorption.

[0038] As an optional implementation, the bottom ends of a plurality of pillars 4 are fixedly connected in the first box 14 , the pillars 4 are evenly arranged in the first box 14 , and the top ends of the pillars 4 are fixedly connected to the bottom of the porous metal plate 1 .

[0039] The first box body 14 is made of thin plates with good thermal insulation performance. Because the porous metal plate 1 is thin and soft, six pillars 4 for supporting the porous metal plate 1 are fixed inside the empty box to avoid the porous metal plate 1 from being concave in the middle.

[0040] As an optional embodiment, the exhaust assembly includes a tapered flow channel 6, the inlet end size of the tapered flow channel 6 is larger than the outlet end size, the inlet end of the tapered flow channel 6 is fixedly connected and connected to one end of the first box body 14, and the outlet end of the tapered flow channel 6 is connected to the exhaust part.

[0041] As an optional embodiment, the exhaust part includes a fan 7 , the air inlet end of the fan 7 is connected to the outlet end of the tapered flow channel 6 through an air outlet pipe 13 , and the air outlet end of the fan 7 is connected to the air inlet end of the cross-hole 8 .

[0042] As an optional embodiment, the air return part includes a second box body 3, and the two second box bodies 3 are respectively fixed to the front and rear sides of the first box body 14. The top of the second box body 3 is set higher than the top of the first box body 14. A strip seam 12 is opened on the top of the second box body 3 toward the porous metal plate 1, and the side walls of the two second box bodies 3 are respectively connected to the first air outlet end and the second air outlet end of the four-way 8.

[0043] As an optional implementation, the first air outlet end and the second air outlet end of the cross-port 8 are respectively connected to the air inlet end of the return air duct 5 , and the air outlet end of the return air duct 5 is connected to the corresponding second box 3 .

[0044] As an optional implementation, a temperature sensor 11 is provided at the collector outlet 10 .

[0045] A converging flow channel 6 is connected to one side of the first box 14, and an air outlet pipe 13 is connected to the fan 7. The function of the fan 7 is to achieve air extraction from one end and then air delivery from the other end. The fan 7 is connected to the air inlet port of the four-way 8. The third air outlet is connected to the collector outlet 10, which is provided with an adjustable valve 9 (to adjust the size of the discharge flow) and a temperature sensor 11 (to facilitate monitoring the outlet temperature). Two insulating narrow strip second boxes 3, which are also surrounded by thin plates with good thermal insulation performance, are attached to both sides of the first box 14. The second box 3 is not connected to the first box 14 in the middle, and the lower end is flush, but the height is higher than the surface of the porous metal plate 1. The two second boxes 3 have two strip slits 12 on the side facing the first box close to the upper part of the porous metal plate 1. The other side of the second box is connected to the return air pipe 5, which connects the first air outlet end and the second air outlet end of the four-way 8.

[0046] The tapered flow channel 6 ensures the uniformity of the air intake of the air intake holes 2 on the porous metal plate 1 (uniform air intake). If there is no tapered flow channel 6, the air outlet pipe 13 connected to the fan 7 is directly connected to the first box 14 with the porous metal plate 1, which will result in a large amount of air intake from the small holes of the porous metal plate 1 near the fan end, and a small amount of air intake from the air intake holes 2 far from the fan end and stay at the tail of the first box 14, resulting in poor air flow, which is far from the expected effect.

[0047] The present invention sets an adjustable valve 9 at the collector outlet 10, controls the opening of the adjustable valve 9, controls the circulation ratio, and monitors the outlet temperature at the same time, thereby realizing controllable regulation of the outlet temperature. When the valve opening is large, the air flow through the valve is large, so the amount of heated air participating in the circulation is small, so that most of the air passing through the porous metal plate 1 still comes from the outside atmosphere, so that the exhaust temperature will not be too high. Therefore, to make the exhaust air temperature as high as possible, adjust the valve to allow a small amount of air to be discharged, and as much air as possible to participate in the circulation during the heating process, the proportion of cold air in the external environment sucked in is small, so that the exhaust air temperature is high.

[0048] Utilize the extraction from the collector outlet 10, then use this part of hot air to form a single or double-sided jet on the surface of the porous metal plate 1, and be sucked by the porous metal plate 1 again to realize the recirculation heating (air reheating) of air. The whole set of devices utilizes part of the heated air to participate in the next cycle, thereby the working mechanism of being heated many times. In this device, the air absorbed by the porous metal plate 1 includes two parts, one part comes from the air that has been heated by the side jet, and the other part comes from the air that has not been heated in the external environment above the porous metal plate 1. When the fan 7 is working, after the air is sucked from the top of the porous metal plate 1, it flows through the gradually contracting flow channel 6, the air outlet pipe 13, the fan 7, through the four-way 8, and is transported to the second box 3 on both sides through the return air pipe 5 on both sides. The second box 3 is driven by the high pressure of the fan 7 to supply air, and the air inside passes through the porous metal plate 1 surface in the form of a high-speed jet, thereby being absorbed by the porous metal plate 1. In this way, the air that has just been heated is heated again by passing through the porous metal plate 1, and this reciprocating process increases the air outlet temperature of the collector and improves the thermal efficiency of the device.

[0049] Furthermore, the appropriate number of return air ducts 5 on both sides also plays a certain role: on the one hand, multiple return air ducts 5 simultaneously supply air to the second boxes 3 on both sides, which can avoid the phenomenon of excessive local air pressure in the second boxes 3, thereby ensuring that the side air supply emitted from the second boxes 3 is more uniform; on the other hand, multiple return air ducts 5 can also appropriately increase the along-the-way resistance and local resistance, so that when the adjustable valve 9 is fully opened, all the air can flow out from the outlet, making the monitored temperature more representative. Of course, installing valves on the two return air ducts 5 connected to the first air outlet end and the second air outlet end respectively can also play the same role.

[0050] The adjustable valve 9 is combined with the temperature sensor 11 to monitor and realize the closed-loop control of the temperature of the collector outlet 10. When the working state of the fan 7 is constant, the size of the exhaust air volume can be controlled by adjusting the valve opening size of the adjustable valve 9, thereby controlling the flow rate and flow rate of the side-sending jet air sent back to the second boxes 3 on both sides. For example: if it is necessary to lower the outlet air temperature of the device, the valve opening is appropriately increased. Due to the large resistance of the pipes on both sides, more air will be discharged directly through the adjacent pipes with larger valve openings. Since the working state of the fan remains unchanged, the extracted flow rate is certain. Therefore, the air flow rate sent to the second boxes 3 on both sides of the porous metal plate 1 through the return air duct 5 will be reduced, thereby reducing the heated air flow rate participating in the secondary circulation. In this way, the porous metal plate 1 will directly absorb more cold air from the external environment, thereby reducing the outlet temperature; when it is necessary to increase the outlet air temperature of the device, the valve opening of the adjustable valve 9 is appropriately reduced, so that the amount of discharged air is reduced, and more heated air is sent back to the second boxes 3 on both sides through the return air duct, participating in the secondary circulation in the form of jets (the circulation ratio is increased), so that the outlet temperature is improved.

[0051] The working principle of this device is:

[0052] The device can be directly exposed to the external environment. When the fan is working, the air on the porous metal plate 1 can be sucked in from the air intake hole 2 and heated at the same time, and then enter the first box 14 below. Then the air flows through the gradually contracting flow channel 6 and is sucked in by the fan 7 through the air outlet pipe 13. The fan 7 sends the hot air into the four-way through the air inlet port of the "cross" four-way 8, and the heated air is sent to the other three outlets. When the adjustable valve 9 is completely closed, the air is sent to the return air pipe 5 on both sides through the first outlet end and the second outlet end on both sides of the four-way 8, and arrives at the second box 3 on both sides of the porous metal plate 1 respectively. Since new hot air flows into the second box 3, the pressure increases, so the air in the box passes through the strip slit 12, in the form of a jet, and is shot to the surface of the porous metal plate 1, forming an air curtain. Because there is no cover plate on the top of the porous metal plate 1, and there is often cross wind flowing through the external environment, it will take away the heat on the surface of the metal plate and interfere with the air flow on the top of the collector. Part of the heated air in the form of a jet will diffuse upward into the atmosphere, and the rest of the air will be re-inhaled by the porous metal plate 1, so that the air that has just been heated will re-enter the device for the next cycle, and repeat in sequence, thereby playing the role of multiple heating; when the adjustable valve 9 is partially opened, part of the air will be directly discharged from the collector outlet 10 connected to the adjustable valve 9, and the remaining air will still be sent to the second box 3 on both sides through the first air outlet end and the second air outlet end after four-way diversion along the return air duct 5 on both sides, and continue to be ejected to the surface of the porous metal plate 1 in the form of a jet, so that it will be absorbed and heated again to participate in the next cycle, so that the size of the opening of the adjustable valve 9 can control the amount of return air (also called air circulation ratio); when the adjustable valve 9 is fully opened, affected by the resistance along the return air duct 5 on both sides and the local resistance, the hot air will directly choose the collector outlet 10 with the smallest resistance and the closest adjustable valve 9 to be discharged.

[0053] As an optional implementation, the porous metal plate 1 is a metal plate with a thickness of 2 mm.

[0054] As an optional implementation, the porous metal plate 1 is a copper plate or an aluminum plate.

[0055] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0056] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A reflow solar air collector, characterized in that: include: A first box body (14), wherein a heat absorbing and air absorbing portion is provided on the top of the first box body (14), and the remaining side walls of the first box body (14) are heat-insulated; An exhaust component, wherein the air inlet end of the exhaust component is connected to one end of the first box body (14); A four-way (8), wherein the air inlet end of the four-way (8) is connected to the air outlet end of the exhaust assembly, the third air outlet end of the four-way (8) is connected to the collector outlet (10) via an adjustable valve (9), the first air outlet end and the second air outlet end of the four-way (8) are respectively connected to the air inlet end of the air return part, and the air outlet end of the air return part is arranged toward the air inlet end of the heat absorption air intake part; The air inlet end of the air return part sucks the air inside the first box (14) and sprays it out from the air outlet end of the air return part to form an air curtain.

2. A reflow solar air collector according to claim 1, characterized in that: The heat absorption and air intake part comprises a porous metal plate (1), the porous metal plate (1) is fixedly connected to the top of the first box body (14), and a plurality of air intake holes (2) are provided on the porous metal plate (1).

3. A reflow solar air collector according to claim 2, characterized in that: The bottom ends of a plurality of pillars (4) are fixedly connected in the first box (14); the pillars (4) are evenly arranged in the first box (14); and the top ends of the pillars (4) are fixedly connected to the bottom of the porous metal plate (1).

4. A reflow solar air collector according to claim 1, characterized in that: The exhaust assembly comprises a tapered flow channel (6), the inlet end size of the tapered flow channel (6) being larger than the outlet end size, the inlet end of the tapered flow channel (6) being fixedly connected to and connected with one end of the first box body (14), and the outlet end of the tapered flow channel (6) being connected with an exhaust portion.

5. A reflow solar air collector according to claim 4, characterized in that: The exhaust part comprises a fan (7), the air inlet end of the fan (7) is connected to the outlet end of the tapered flow channel (6) through an air outlet pipe (13), and the air outlet end of the fan (7) is connected to the air inlet end of the cross-connection (8).

6. A reflow solar air collector according to claim 2, characterized in that: The air return section comprises a second box body (3), two second box bodies (3) are respectively fixed to the front side and the rear side of the first box body (14), the top of the second box body (3) is arranged higher than the top of the first box body (14), a strip-shaped slit (12) is provided on the top of the second box body (3) facing the porous metal plate (1), and the side walls of the two second box bodies (3) are respectively connected to the first air outlet end and the second air outlet end of the four-way (8).

7. A reflow solar air collector according to claim 6, characterized in that: The first air outlet end and the second air outlet end of the four-way (8) are respectively connected to the air inlet end of the return air pipe (5), and the air outlet end of the return air pipe (5) is connected to the corresponding second box (3).

8. A reflow solar air collector according to claim 1, characterized in that: The collector outlet (10) is provided with a temperature sensor (11).

9. A reflow solar air collector according to claim 2, characterized in that: The porous metal plate (1) is a metal plate with a thickness of 2 mm.

10. A reflow solar air collector according to claim 2, characterized in that: The porous metal plate (1) is a copper plate or an aluminum plate.

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