A recirculating solar air collector

Abstract

This invention belongs to the field of solar heating technology, and particularly relates to a recirculating solar air collector, comprising: a first housing, the top of which is provided with a heat-absorbing air intake section, and the remaining side walls of the first housing are insulated; an exhaust assembly, the air inlet of which is connected to one end of the first housing; a four-way valve, the air inlet of which is connected to the air outlet of the exhaust assembly, the third air outlet of which is connected to the collector outlet via an adjustable valve, the first and second air outlets of which are respectively connected to the air inlet of a return air section, the air outlet of which is oriented towards the air inlet of the heat-absorbing air intake section; the air inlet of the return air section draws in air from inside the first housing and ejects it from the air outlet of the return air section to form an air curtain. This device generates a high-speed jet by drawing air from its own interior and forming an air curtain on the surface of the heat-absorbing air intake section, which can achieve heat insulation and heat preservation, and at the same time realize multiple air circulation heating.

Description

Technical Field

[0001] This invention belongs to the field of solar heating technology, and particularly relates to a recirculating solar air collector. Background Technology

[0002] Solar energy, as a renewable energy source, can effectively alleviate dependence on fossil fuels. The world is facing severe challenges posed by climate change, and reducing greenhouse gas emissions has become a common goal for all countries.

[0003] Solar collectors, as a clean and renewable energy technology, help reduce greenhouse gas emissions and contribute to addressing global energy challenges. Using solar collectors can reduce the use of traditional energy sources such as coal and oil, lower air pollution, improve environmental quality, and play a positive role in curbing global warming. In recent years, continuous innovation in photothermal materials and heat-absorbing coatings, along with the application of intelligent control technologies (such as flow monitoring and temperature regulation), has significantly improved the thermal efficiency of solar collectors, enhancing their operational efficiency and reducing the manufacturing and maintenance costs of solar thermal equipment.

[0004] Solar collectors can be classified into various types based on their structure and working principle, each with its own unique advantages and disadvantages. Taking traditional flat-plate collectors and infiltrated air collectors as examples, flat-plate collectors, due to their structure, reflect some sunlight through the glass cover, reducing the heat absorption and resulting in significant heat loss. Infiltrated air collectors, due to the good thermal conductivity of metal, easily lose heat from the collector's interior in cold environments or when not in use for extended periods, leading to substantial heat loss. Therefore, to improve heat absorption efficiency, reduce heat loss, and simultaneously increase or achieve the desired outlet air temperature, a recirculation-type solar air collector is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a recirculating solar air collector to solve the above-mentioned problems.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] A recirculating solar air collector includes:

[0008] The first housing has a heat-absorbing and air-absorbing section on its top, and the remaining side walls of the first housing are insulated.

[0009] An exhaust assembly, wherein the air inlet of the exhaust assembly is connected to one end of the first housing;

[0010] The four-way valve has an air inlet end connected to the air outlet end of the exhaust assembly, and a third air outlet end connected to the collector outlet via an adjustable valve. The first and second air outlet ends of the four-way valve are respectively connected to the air inlet end of the return air section, and the air outlet end of the return air section is arranged facing the air inlet end of the heat absorption and air intake section.

[0011] The air inlet of the return air section draws in air from inside the first housing and sprays it out from the outlet of the return air section to form an air curtain.

[0012] Optionally, the heat-absorbing and air-absorbing part includes a porous metal plate, which is fixed to the top of the first housing, and the porous metal plate has a plurality of air-absorbing holes.

[0013] Optionally, the bottom ends of several pillars are fixedly connected to 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 converging flow channel, the inlet size of which is larger than the outlet size, the inlet of which is fixedly connected to and communicates with one end of the first housing, and the outlet of which is connected to an exhaust section.

[0015] Optionally, the exhaust section includes a fan, the air inlet of which is connected to the outlet of the converging flow channel via an air outlet pipe, and the air outlet of which is connected to the air inlet of the four-way valve.

[0016] Optionally, the return air section includes a second housing, with two second housings fixedly connected to the front and rear sides of the first housing, respectively. The top of the second housing is higher than the top of the first housing, and a strip slit is opened on the side of the top of the second housing facing the porous metal plate. The side walls of the two second housings are respectively connected to the first and second air outlets of the four-way valve.

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

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

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

[0020] Optionally, the porous metal plate is either 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 this device operates in the external environment, during the operation of the exhaust assembly, air from the first chamber is transported to the inlet of the four-way valve. Under air pressure, the air is drawn into the first chamber through the heat-absorbing intake section and simultaneously heated. The heated air is then sent to the other three outlets: the first, second, and third outlets. When the adjustable valve is fully closed, air is sent to the return air sections on both sides of the four-way valve through the first and second outlets. The outlets of these return air sections face the inlet of the heat-absorbing intake section, and the return air sections jet the air onto the surface of the heat-absorbing intake section, forming an air curtain on the outer surface of the porous metal plate. Because the heat-absorbing intake section has no cover plate at the top, and crosswinds frequently flow through the external environment, they carry away heat from the surface of the porous metal plate of the collector, resulting in significant heat loss. In the jet-form heating process, a portion of the heated air diffuses upwards into the atmosphere, while the remaining air is re-drawn in by the heat-absorbing intake section. This allows some of the heated air to re-enter the device for the next heating cycle, repeating this process multiple times to achieve multiple heating effects. When the adjustable valve is partially open, some air is directly discharged from the collector outlet connected to the adjustable valve. The remaining air is still split through a four-way valve and enters the corresponding return section through the first and second outlets, continuing to be jetted onto the surface of the heat-absorbing intake section for further absorption and heating to participate in the next cycle. The opening of the adjustable valve controls the amount of return air (also called the air circulation ratio). When the adjustable valve is fully open, due to the frictional resistance and local resistance of the return sections on both sides, the hot air will directly choose the collector outlet with the adjustable valve, which has the least resistance, for discharge. Based on the needs of practical applications, i.e., based on the required outlet air temperature, the air in the circulation section is reduced when the temperature is high and increased when the temperature is low, ultimately achieving temperature control. Compared to traditional technologies, this device utilizes a high-speed jet of air to form an air curtain on the surface of the heat-absorbing intake section. This not only prevents the heat from the porous metal plate from diffusing outwards but also isolates the collector from interference by external crosswinds, thus providing insulation and effectively improving the thermal efficiency of the permeable air collector. Compared to drawing air from the external environment to form a side-flow jet, another advantage of this device is that the air source for the air curtain is pre-heated air. This allows for secondary or even multiple heat exchanges between the air and the porous metal plate, increasing the outlet temperature. This device enables multiple cycles of air reheating, thereby raising the air outlet temperature of the collector. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

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

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

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

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

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] Reference Figures 1 to 3 This invention discloses a recirculating solar air collector, comprising:

[0031] The first box 14 has a heat-absorbing and air-absorbing part on the top and the other side walls of the first box 14 are insulated.

[0032] The exhaust assembly has its air inlet connected to one end of the first housing 14;

[0033] Four-way 8, the air inlet of four-way 8 is connected to the air outlet of the exhaust component, the third air outlet of four-way 8 is connected to the collector outlet 10 through the adjustable valve 9, the first air outlet and the second air outlet of four-way 8 are respectively connected to the air inlet of the return air section, and the air outlet of the return air section is set towards the air inlet of the heat absorption and air intake section.

[0034] When this device operates in the external environment, during the operation of the exhaust assembly, air from the first housing 14 is transported to the air inlet of the four-way 8. Under air pressure, the air is drawn into the first housing 14 through the heat-absorbing intake section and simultaneously heated. The heated air is then sent to the other three ports: the first outlet, the second outlet, and the third outlet. When the adjustable valve 9 is fully closed, air is sent to the return air sections on both sides of the four-way 8 through the first and second outlets. The outlets face the air inlet of the heat-absorbing intake section, and the return air sections jet the air onto the surface of the heat-absorbing intake section, forming an air curtain. Because the heat-absorbing intake section has no cover plate on top, and crosswinds frequently flow through the external environment, they carry away heat from the surface of the metal plate and interfere with the airflow above the collector. Due to the heating effect of the metal plate, the heated air in jet form diffuses upward into the atmosphere, while the remaining air is re-drawn in by the heat-absorbing intake section, allowing some of the heated air to re-enter the device for the next cycle. This process is repeated, resulting in multiple heating cycles. When the adjustable valve 9 is partially open, some air is directly discharged from the collector outlet 10 connected to the adjustable valve 9. The remaining air is still diverted through the four-way valve 8 and enters the corresponding return air section through the first and second outlets, continuing to be jetted onto the surface of the heat-absorbing intake section, where it is absorbed and heated again to participate in the next cycle. In this way, 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 open, due to the frictional resistance and local resistance of the return air sections on both sides, the hot air will directly choose the collector outlet 10 with the least resistance and closest connection to the adjustable valve 9 for discharge. Compared to traditional technologies, this device uses a high-speed jet of air to form an air curtain on the surface of the heat-absorbing intake section, preventing hot air from diffusing outwards and isolating it from interference from external crosswinds, thus providing heat insulation and improving thermal efficiency. Compared to side-supply jets where the air comes directly from the environment, another advantage of this device is that the air source for the air curtain is preheated air. This allows for secondary or even multiple heat exchanges between the air and the porous metal plate, increasing the outlet temperature. This device can achieve multiple cycles of air reheating, thereby increasing the air outlet temperature of the solar collector.

[0035] As an alternative implementation, the air source for forming the jet curtain can be drawn from the external environment, which simplifies the overall system composition. However, it is preferred to draw air from within the system.

[0036] As an optional implementation, the heat absorption and air intake section includes a porous metal plate 1, which is fixed to the top of the first housing 14, and a plurality of air intake holes 2 are provided on the porous metal plate 1.

[0037] The porous metal plate 1 does not reflect sunlight compared to a glass cover, thus improving the efficiency of sunlight heat absorption.

[0038] As an optional implementation, the bottom ends of several support columns 4 are fixedly connected inside the first housing 14. The support columns 4 are evenly arranged inside the first housing 14, and the top ends of the support columns 4 are fixedly connected to the bottom of the porous metal plate 1.

[0039] The first box 14 is a box made of thin plates with good thermal insulation properties. Because the porous metal plate 1 is thin and soft, six pillars 4 are fixed inside the empty box to support the porous metal plate 1, so as to avoid the porous metal plate 1 from being dented in the middle.

[0040] As an optional implementation, the exhaust assembly includes a converging flow channel 6, the inlet end of which is larger than the outlet end. The inlet end of the converging flow channel 6 is fixedly connected to and communicates with one end of the first housing 14, and the outlet end of the converging flow channel 6 is connected to an exhaust section.

[0041] As an optional implementation, the exhaust section includes a fan 7, the air inlet of the fan 7 is connected to the outlet of the converging flow channel 6 through the air outlet pipe 13, and the air outlet of the fan 7 is connected to the air inlet of the four-way valve 8.

[0042] As an optional implementation, the return air section includes a second housing 3. The two second housings 3 are respectively fixed to the front and rear sides of the first housing 14. The top of the second housing 3 is higher than the top of the first housing 14. A strip slit 12 is opened on the side of the top of the second housing 3 facing the porous metal plate 1. The side walls of the two second housings 3 are respectively connected to the first air outlet and the second air outlet of the four-way 8.

[0043] As an optional implementation, the first and second air outlets of the four-way 8 are respectively connected to the air inlet of the return air pipe 5, and the air outlet of the return air pipe 5 is connected to the corresponding second housing 3.

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

[0045] A tapered flow channel 6 is connected to one side of the first housing 14, followed by an air outlet duct 13 connected to a fan 7. The fan 7 is used to draw air from one end and then deliver air from the other end. The fan 7 is connected to the air inlet port of the four-way valve 8, and the third air outlet port is connected to the collector outlet 10. An adjustable valve 9 (to adjust the discharge flow rate) and a temperature sensor 11 (to monitor the outlet temperature) are mounted on the fan 7. Two insulated narrow strip second housings 3, also made of thin plates with good thermal insulation properties, are attached to the two sides of the first housing 14. The second housings 3 are not connected to the first housing 14 in the middle. Their lower ends are flush, but their height is higher than the surface of the perforated metal plate 1. On the side of the two second housings 3 facing the first housing, two strip slits 12 are opened at the top of the perforated metal plate 1. The other side of the second housings is connected to a return air duct 5, which connects to the first and second air outlet ports of the four-way valve 8.

[0046] The tapered flow channel 6 ensures the uniformity of air intake through the air inlet 2 on the porous metal plate 1 (uniform air intake). Without the tapered flow channel 6, the air outlet pipe 13 connecting the fan 7 would be directly connected to the first housing 14 with the porous metal plate 1, resulting in a large air intake through the small holes of the porous metal plate 1 near the fan end, while the air intake through the air inlet 2 far from the fan end would be smaller and linger at the rear of the first housing 14, leading to poor airflow and a significant difference from the expected effect.

[0047] This invention achieves controllable adjustment of the outlet temperature by installing an adjustable valve 9 at the collector outlet 10. By controlling the opening degree of the adjustable valve 9, the circulation ratio is controlled, and the outlet temperature is monitored. When the valve opening is large, the airflow through the valve is large, so the amount of heated air participating in the circulation is small. Thus, most of the air passing through the porous metal plate 1 still comes from the outside atmosphere, resulting in a lower exhaust temperature. Therefore, to maximize the exhaust air temperature, the valve is closed, allowing a smaller amount of air to be discharged, maximizing the air's participation in the circulation during the heating process. This reduces the proportion of cold air drawn in from the outside environment, resulting in a higher exhaust air temperature.

[0048] The system utilizes the principle of air recirculation and reheating (air reheating) by drawing air from the collector outlet 10 and then using this hot air to form a single-sided or double-sided jet on the surface of the porous metal plate 1, which is then drawn back into the porous metal plate 1. The entire device utilizes a portion of the already heated air to participate in the next cycle, thus achieving multiple heating. In this device, the air absorbed by the porous metal plate 1 consists of two parts: one part comes from the side-flowing jet that has already been heated, and the other part comes from the unheated air in the external environment above the porous metal plate 1. When the fan 7 is working, the air is drawn in from above the porous metal plate 1, flows through the converging channel 6, the outlet pipe 13, the fan 7, and through the four-way valve 8, and is transported to the second housings 3 on both sides through the return air pipes 5 on both sides. Driven by the high pressure of the air supplied by the fan 7, the air inside the second housing 3 passes laterally across the surface of the porous metal plate 1 in the form of a high-speed jet, thus being absorbed by the porous metal plate 1. In this way, the air that has just been heated is reheated through the porous metal plate 1, and this process is repeated to increase the air outlet temperature of the collector and improve 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 chambers 3 on both sides, which can avoid the phenomenon of excessive local air pressure in the second chambers 3, thereby ensuring that the side air supply ejected from the second chambers 3 is more uniform; on the other hand, multiple return air ducts 5 can also appropriately increase the friction resistance and local resistance, so that when the adjustable valve 9 is fully open, all air is guaranteed to 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 and second outlets can also achieve the same effect.

[0050] The adjustable valve 9, combined with the temperature sensor 11, enables closed-loop control of the collector outlet temperature 10. When the fan 7 is in a constant operating state, the amount of air discharged can be controlled by adjusting the opening of the adjustable valve 9, thereby controlling the flow rate and volume of the side-feed jet air sent back to the second housings 3 on both sides. For example, to lower the outlet air temperature, the valve opening is appropriately increased. Due to the greater resistance of the pipes on both sides, more air will be directly discharged through the pipe with the larger valve opening. Since the fan's operating state remains unchanged, the extracted flow rate is constant. Therefore, the air flow rate sent to the second chambers 3 on both sides of the porous metal plate 1 through the return air pipe 5 will decrease, thus reducing the flow rate of heated air participating in the secondary circulation. As a result, the porous metal plate 1 will directly absorb more cold air from the outside environment, thereby lowering the outlet temperature. When it is necessary to raise the outlet air temperature, the valve opening of the adjustable valve 9 is appropriately reduced. This reduces the amount of air discharged, and more heated air is sent back to the second chambers 3 on both sides through the return air pipe, participating in the secondary circulation in the form of a jet (increasing the circulation ratio). This achieves the effect of raising the outlet temperature.

[0051] The working principle of this device is as follows:

[0052] The device can be directly exposed to the external environment. When the fan is working, it draws in air from the porous metal plate 1 through the intake port 2, heats it, and sends it into the first housing 14 below. The air then flows through the converging channel 6 and is drawn in by the fan 7 through the outlet pipe 13. The fan 7 sends the heated air into the four-way valve 8 through the inlet port, and the heated air is sent to the other three outlets. When the adjustable valve 9 is fully closed, the air is sent to the return air pipes 5 on both sides of the four-way valve 8 through the first and second outlets on both sides, and arrives at the second housings 3 on both sides of the porous metal plate 1. As fresh hot air flows into the second housings 3, the pressure increases, so the air inside the housing is jetted onto the surface of the porous metal plate 1 through the strip slit 12, forming an air curtain. Because the porous metal plate 1 has no cover plate on top, and crosswinds often flow through the external environment, they will carry away the heat from the surface of the metal plate and interfere with the airflow above the collector. The heated air in jet form diffuses upwards into the atmosphere, while the remaining air is re-absorbed by the porous metal plate 1. This re-absorbed air then re-enters the device for the next cycle, repeating the process to achieve multiple heating cycles. When the adjustable valve 9 is partially open, some air is directly discharged from the collector outlet 10 connected to the adjustable valve 9. The remaining air is still diverted through the four-way valve and then sent to the second housings 3 on both sides via the first and second outlet ports along the return air ducts 5. It continues to be jetted onto the surface of the porous metal plate 1, where it is again absorbed and heated to participate in the next cycle. The opening of the adjustable valve 9 controls the amount of return air (also called the air circulation ratio). When the adjustable valve 9 is fully open, due to the frictional resistance and local resistance of the return air ducts 5, the hot air directly selects the collector outlet 10 with the adjustable valve 9, which has the least resistance, for discharge.

[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 either a copper plate or an aluminum plate.

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

[0056] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A recirculating solar air collector, characterized in that, include: The first box (14) has a heat-absorbing and air-absorbing part on the top and the other side walls of the first box (14) are insulated. An exhaust assembly, wherein the air inlet of the exhaust assembly is connected to one end of the first housing (14); Four-way (8), the air inlet of the four-way (8) is connected to the air outlet of the exhaust assembly, the third air outlet of the four-way (8) is connected to the collector outlet (10) through an adjustable valve (9), the first air outlet and the second air outlet of the four-way (8) are respectively connected to the air inlet of the return air section, and the air outlet of the return air section is set towards the air inlet of the heat absorption and air intake section; The air inlet of the return air section draws in the air inside the first box (14) and sprays it out from the air outlet of the return air section to form an air curtain; The heat-absorbing and air-absorbing part includes a porous metal plate (1), which is fixed to the top of the first box (14), and a plurality of air-absorbing holes (2) are provided on the porous metal plate (1). The exhaust assembly includes a converging flow channel (6), the inlet size of which is larger than the outlet size. The inlet of the converging flow channel (6) is fixedly connected to and communicates with one end of the first housing (14), and the outlet of the converging flow channel (6) is connected to an exhaust section.

2. A recirculating solar air collector according to claim 1, characterized in that: The first box (14) is fixed to the bottom of several pillars (4), the pillars (4) are evenly arranged inside the first box (14), and the top of the pillars (4) is fixed to the bottom of the porous metal plate (1).

3. A recirculating solar air collector according to claim 1, characterized in that: The exhaust section includes a fan (7), the air inlet of the fan (7) is connected to the outlet of the tapered channel (6) through the air outlet pipe (13), and the air outlet of the fan (7) is connected to the air inlet of the four-way (8).

4. A recirculating solar air collector according to claim 1, characterized in that: The return air section includes a second housing (3), and two second housings (3) are respectively fixed to the front and rear sides of the first housing (14). The top of the second housing (3) is set higher than the top of the first housing (14). A strip slit (12) is opened on the side of the top of the second housing (3) facing the porous metal plate (1). The side walls of the two second housings (3) are respectively connected to the first air outlet and the second air outlet of the four-way (8).

5. A recirculating solar air collector according to claim 4, characterized in that: The first and second air outlets of the four-way valve (8) are respectively connected to the air inlet of the return air pipe (5), and the air outlet of the return air pipe (5) is connected to the corresponding second housing (3).

6. A recirculating solar air collector according to claim 1, characterized in that: A temperature sensor (11) is installed at the collector outlet (10).

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

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

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