An intelligent fresh air system with indirect evaporative cooling and thermoelectric heat recovery

Abstract

This invention belongs to the field of refrigeration and air conditioning technology, specifically an indirect evaporative cooling-thermal heat recovery intelligent fresh air system. It includes an indirect evaporative cooling system with air channels connected in series and a heat pipe-assisted thermoelectric heat recovery system. A closed-loop cooling water circuit is achieved through a spray device and a water tank. Sensors are used for signal acquisition, and control components are used for regulation. This invention organically couples indirect evaporative cooling, flat plate heat pipes, and thermoelectric cooling / heating technology, saving energy, improving the system's energy efficiency ratio, and meeting people's needs for fresh air and indoor air quality.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of refrigeration and air conditioning, and particularly relates to an indirect evaporative cooling-thermoelectric heat recovery intelligent fresh air system. BACKGROUND

[0002] According to the data of World Energy Outlook 2024 of the International Energy Agency, the energy consumption of the building sector accounted for about 28% of the total global final energy consumption in 2023. In the composition of total building energy consumption, the energy consumption of heating, ventilation and air conditioning accounts for about 50%, which has significant energy-saving potential. Improving the air tightness of building envelopes is a key technical path to realize this potential, but enhancing the air tightness of buildings not only reduces heat loss, but also hinders the timely dilution and discharge of indoor pollutants and harmful substances. Studies have shown that modern urban residents spend about 80%-90% of their time indoors, and indoor air quality directly affects human health and work efficiency. Therefore, while achieving energy saving, it is urgent to solve the problem of ensuring indoor air quality.

[0003] As an important part of the heating, ventilation and air conditioning system, the fresh air system plays a key role in meeting the oxygen consumption of indoor personnel, diluting pollutants and maintaining air quality. At present, various types of fresh air treatment devices have been widely used in public buildings, while natural ventilation by opening windows is still commonly used in residential buildings, resulting in high energy consumption of fresh air. During air conditioning operation, there is often a large temperature and humidity difference between indoor and outdoor air, and if the indoor exhaust air is directly discharged to the outdoor air, it will cause significant energy waste. Effective recovery of energy from exhaust air can achieve the dual goals of building energy saving and indoor air quality improvement, and a fresh air heat recovery device is an effective way to solve this contradiction.

[0004] Existing fresh air heat recovery devices still fall short in coordinating energy conservation and air quality. Indirect evaporative cooling (IEC) technology, as a sustainable refrigeration technology, demonstrates irreplaceable environmental advantages compared to other refrigeration systems (such as vapor compression systems), significantly reducing operating energy consumption while mitigating the greenhouse effect and reducing carbon emissions. Although the refrigeration performance of evaporative cooling technology is highly dependent on ambient temperature and humidity conditions, organically coupling it with other refrigeration technologies (such as thermoelectric refrigeration and vapor compression refrigeration) to construct a composite refrigeration system can effectively compensate for the shortcomings of a single technology, thereby significantly broadening its effective operating range and improving cooling stability under all operating conditions. Taking thermoelectric refrigeration as an example, this technology features no moving parts, long lifespan, compact size, and rapid response. Its cooling capacity can be flexibly adjusted through input current, facilitating precise temperature control, making it an ideal auxiliary cold source in composite systems. To further enhance the efficiency of thermoelectric modules, flat plate heat pipes can be introduced as a heat transfer enhancement method. Relying on the evaporation and condensation cycle of the working fluid inside the heat pipe to transfer heat, its latent heat of phase change has a heat transfer intensity far exceeding that of ordinary sensible heat transfer, exhibiting extremely high thermal conductivity. By tightly coupling heat pipes to the hot and cold ends of the thermoelectric module, the directional transport of heat can be greatly accelerated, effectively reducing contact thermal resistance. This allows the thermoelectric unit to operate at a higher efficiency, ultimately improving the overall performance of the composite fresh air system.

[0005] Evaporative cooling, thermoelectric cooling / heating, and flat-plate heat pipe cooling each have their advantages. Existing research mostly focuses on single technologies, composite technologies combining evaporative cooling and thermoelectricity, or composite technologies combining thermoelectricity and heat pipes. Research integrating all three technologies and applying them to fresh air systems is still rare. Patents with application numbers CN202020116767.1, CN202122390005.8, and CN201910838346.1 propose different structures for indirect evaporative cooling fresh air systems. However, single indirect evaporative cooling systems lack sufficient temperature and humidity control capabilities for fresh air, have low energy recovery rates, and are difficult to adapt to complex and variable outdoor weather conditions. Patent application number CN202021151331.2 discloses a flat-plate heat pipe thermoelectric heat recovery fresh air unit. Although it combines thermoelectricity with flat-plate heat pipes, it relies solely on thermoelectric elements for active temperature and humidity control of the fresh air to bear the entire load, resulting in high system energy consumption. Summary of the Invention

[0006] The purpose of this invention is to provide an intelligent fresh air system with indirect evaporative cooling and thermoelectric heat recovery, which organically couples indirect evaporative cooling, flat plate heat pipes and thermoelectric cooling / heating technology, saving energy consumption, improving the system's energy efficiency ratio, and meeting people's needs for fresh air and indoor air quality.

[0007] The technical solution to achieve the purpose of this invention is: an indirect evaporative cooling-thermal heat recovery intelligent fresh air system, including an indirect evaporative cooling system and a heat pipe-assisted thermoelectric heat recovery system connected in series with air channels, a closed-loop cooling water circuit realized by a spray device and a water tank, as well as sensors for signal acquisition and control components for adjustment.

[0008] Compared with the prior art, the significant advantages of the present invention are:

[0009] (1) A fresh air treatment system with summer and winter dual-mode operation was constructed: in summer, the indoor exhaust air cooling capacity was recovered by indirect evaporative cooler to pre-cool the fresh air, and in winter, the indoor exhaust air waste heat was recovered to preheat the fresh air, so as to realize the efficient use of exhaust air energy and significantly reduce the energy consumption of fresh air treatment.

[0010] (2) Introducing thermoelectric cooling / heating technology as an active temperature and humidity control unit: By changing the direction of the working current of the thermoelectric module, the hot and cold ends of the thermoelectric element can be interchanged. In summer, the fresh air can be cooled and dehumidified, and in winter, the fresh air can be heated and warmed. By adjusting the input current, the temperature and humidity of the supply air can be actively and accurately controlled, making up for the shortcomings of the traditional fresh air heat recovery device in terms of temperature and humidity regulation.

[0011] (3) The heat pipe array is combined with the thermoelectric module. The phase change heat transfer of the working fluid inside the flat heat pipe is used to enhance the heat transfer effect of the hot and cold ends of the thermoelectric module. The heat exchange area is expanded by arranging fins on the surface of the heat pipe, thereby improving the overall heat exchange performance of the system. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the circulation and control method of the intelligent fresh air system with indirect evaporative cooling-thermal heat recovery according to the present invention;

[0013] Figure 2 This is a schematic diagram of a heat pipe-assisted thermoelectric cooling / heating unit.

[0014] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Detailed Implementation

[0015] The terminology used in this invention is for illustrative purposes only and is not intended to limit the invention. The following description, in conjunction with the appendix, further clarifies this concept. Figures 1-2 The following is a detailed description of some embodiments of the present invention.

[0016] like Figure 1 and Figure 2 As shown, an intelligent fresh air system with indirect evaporative cooling and thermoelectric heat recovery includes an indirect evaporative cooling system and a heat pipe-assisted thermoelectric heat recovery system.

[0017] The indirect evaporative cooling system includes a housing and a cross-flow indirect evaporative cooler 101, a first spray device 102, a first variable frequency fan 103, a second variable frequency fan 104, and a first variable frequency water pump 105 disposed inside the housing. The first variable frequency fan 103 is disposed at the inlet of the primary air passage (dry passage) of the indirect evaporative cooler 101 and connected to the outdoor fresh air inlet. The second variable frequency fan 104 is disposed at the inlet of the secondary air passage (wet passage) of the indirect evaporative cooler and connected to the indoor exhaust outlet. The first spray device 102, the first variable frequency water pump 105, and the water tank are connected by water pipes. In the summer operation mode, the first spray device 102 is used to spray circulating water into the wet passage of the indirect evaporative cooler 101, so that a water film is formed on the heat exchange wall of the wet passage. The secondary air flowing through the wet passage exchanges heat and mass with the water film, and the evaporative heat absorption effect of water is used to reduce the temperature of the heat exchange wall, thereby achieving indirect cooling of the primary air in the dry passage. The circulating water after spraying flows back to the water tank through a return water pipe located at the bottom of the tank, achieving recycling. The primary and secondary air passage outlets of the indirect evaporative cooler 101 are connected to the primary and secondary air passage inlets of the heat pipe-assisted thermoelectric heat recovery system, respectively. The heat pipe-assisted thermoelectric heat recovery system includes two sets of tanks, multiple sets of heat pipe-assisted thermoelectric modules connected in series, a primary air passage, a secondary air passage, a second spray device 205, and a second variable frequency water pump 206. The multiple sets of heat pipe-assisted thermoelectric modules connected in series are straddling the two sets of tanks. The thermoelectric modules and the portion of the flat heat pipe located between the two tanks are filled with heat insulation cotton and sealed with heat-insulating aluminum foil tape to reduce heat exchange with the outside air. The second spray device 205, the second variable frequency water pump 206, and the water tank are connected by water pipes. In summer operation mode, the second spray device 205 sprays circulating water into the secondary air channel of the heat pipe-assisted thermoelectric heat recovery system, enabling heat and mass exchange between the circulating water and the secondary air. The evaporation of water absorbs heat, lowering the secondary air temperature and thus enhancing heat exchange between the condensation section of the second flat plate heat pipe array 203 and the secondary air. The sprayed circulating water returns to the water tank via a return pipe located at the bottom of the enclosure, achieving recycling.

[0018] Each heat pipe-assisted thermoelectric module includes a thermoelectric module 201, a first flat plate heat pipe array 202, a second flat plate heat pipe array 203, and fins 204 arranged on the flat plate heat pipe array. The thermoelectric module 201 switches between cooling and heating modes by changing the direction of the input current and actively regulates the air temperature by adjusting the magnitude of the input current. The first flat plate heat pipe array 202 and the second flat plate heat pipe array 203 are used to transfer heat between the hot and cold ends of the thermoelectric module 201, enhancing the heat exchange between the thermoelectric module and the air channel. The fins 204 are used to expand the heat exchange area between the flat plate heat pipe array and the air, enhancing the air-side heat exchange. In the heat pipe assisted thermoelectric module, one end of the first flat plate heat pipe array 202 and the second flat plate heat pipe array 203 are tightly attached to the hot and cold ends of the thermoelectric module 201, respectively; the other ends of the first flat plate heat pipe array 202 and the second flat plate heat pipe array 203 extend into the primary air channel and the secondary air channel of the heat pipe assisted thermoelectric heat recovery system, respectively; the surfaces of the first flat plate heat pipe array 202 and the second flat plate heat pipe array 203 located in the air channel portion are provided with straight fins 204.

[0019] A first temperature and humidity sensor 301 and a second temperature and humidity sensor 302 are respectively installed at the inlet of the primary air passage and the secondary air passage of the indirect evaporative cooler; a third temperature and humidity sensor 303 and a fourth temperature and humidity sensor 304 are respectively installed at the inlet of the primary air passage and the secondary air passage of the heat pipe assisted thermoelectric heat recovery system; and a fifth temperature and humidity sensor 305 and a sixth temperature and humidity sensor 306 are respectively installed at the outlet of the primary air passage and the secondary air passage of the heat pipe assisted thermoelectric heat recovery system.

[0020] A first temperature sensor 308 and a first flow meter 310 are installed at the inlet of the first spray device 102 of the indirect evaporative cooling system, and a second temperature sensor 307 and a second flow meter 309 are installed at the inlet of the second spray device 205 of the heat pipe assisted thermoelectric heat recovery system; an ammeter 311 is connected to the thermoelectric module 201.

[0021] The first to sixth temperature and humidity sensors 301 to 306, the first temperature sensor 307, the second temperature sensor 308, the first flow meter 309, the second flow meter 310, and the ammeter 311 are all connected to the controller 312.

[0022] The present invention utilizes the control method of the above-mentioned indirect evaporative cooling-thermal heat recovery intelligent fresh air system, and the specific steps are as follows:

[0023] Step 1: Start the first variable frequency fan 103 and the second variable frequency fan 104, so that the outdoor fresh air enters the primary air (dry air) channel of the indirect evaporative cooler 101 through the first variable frequency fan 103, and the indoor exhaust air enters the secondary air (humid air) channel of the indirect evaporative cooler 101 through the second variable frequency fan 104; the controller 312 determines the system operation mode according to the inlet temperature and humidity of the primary air channel and the secondary air channel and the preset fresh air outlet temperature and humidity requirements.

[0024] Step 2: In summer operation mode, controller 312 turns on the first variable frequency water pump 105, the second variable frequency water pump 206, and the first and second spray devices 102 and 205; adjusts the current direction of thermoelectric module 201 so that the condensing section of the first flat plate heat pipe array 202 of the thermoelectric heat recovery system is in close contact with the cold end of thermoelectric module 201, and the evaporating section of the second flat plate heat pipe array 203 is in close contact with the hot end of thermoelectric module 201; in winter operation mode, controller 312 turns off the first variable frequency water pump 105, the second variable frequency water pump 206, and the first and second spray devices 102 and 205, and adjusts the current direction of thermoelectric module 201 so that the evaporating section of the first flat plate heat pipe array 202 of the thermoelectric heat recovery system is in close contact with the hot end of thermoelectric module 201, and the condensing section of the second flat plate heat pipe 203 is in close contact with the cold end of thermoelectric module 201.

[0025] Step 3: When the primary air outlet temperature is higher than the summer set value, controller 312 increases the number of thermoelectric modules 201 that are turned on or the magnitude of their input current, and adjusts the fan speed and spray water flow rate to improve the system's cooling capacity. When the primary air outlet temperature is lower than the winter set value, controller 312 increases the number of thermoelectric modules 201 that are turned on or the magnitude of their input current, and adjusts the fan speed accordingly to improve the system's heating capacity. Conversely, controller 312 reduces the number of thermoelectric modules 201 that are turned on or the magnitude of their input current, and adjusts the corresponding actuators in the opposite direction to keep the primary air outlet temperature within the set range. Once the primary air outlet temperature and humidity reach the preset range, controller 312 maintains the current operating state of each actuator. If the fresh air outlet parameters deviate from the preset range again, the above adjustment process is repeated, thereby achieving dynamic control of the system.

[0026] The working principle of the indirect evaporative cooling-thermal heat recovery intelligent fresh air system is as follows:

[0027] During summer operation, the water pump and spray system remain on. The warmer outdoor fresh air, acting as primary air, first enters the dry channel of the cross-flow indirect evaporative cooler (101); the cooler indoor exhaust air, acting as secondary air, enters its wet channel. In the wet channel, the secondary air exchanges heat and mass with the water film formed by the spray water, indirectly absorbing the heat transferred from the primary air in the dry channel, thus pre-cooling the outdoor fresh air. The pre-cooled fresh air then enters the primary air channel of the heat pipe-assisted thermoelectric heat recovery system, undergoes further cooling, and is then delivered indoors. At this time, the cold end of the thermoelectric module (201) is in close contact with the condensation section of the first flat plate heat pipe array (202) to absorb the condensation heat released by that section; while the evaporation section of the first flat plate heat pipe array (202) is located in the primary air channel to absorb the heat from the primary air. Meanwhile, the secondary air, after being cooled and humidified by the outlet of the indirect evaporator (101), enters the secondary air channel of the heat pipe-assisted thermoelectric heat recovery system and, together with the spray water film, absorbs the condensation heat released by the condensation section of the second flat plate heat pipe array (203); the evaporation section of the heat pipe array is in close contact with the hot end of the thermoelectric module (201) to absorb the heat generated therefrom.

[0028] During winter operation, all water pumps and spray devices remain off. At this time, the indirect evaporative cooler (101) functions only as a standard dry sensible heat regenerator. By changing the direction of the operating current of the thermoelectric module (201), its hot and cold ends are interchanged: the evaporation section of the first flat plate heat pipe array (202) is now in close contact with the hot end of the thermoelectric module (201) to absorb the heat it releases, while the cold end of the thermoelectric module (201) is in close contact with the condensation section of the second flat plate heat pipe array (203) to absorb the condensation heat it releases. Regarding the airflow, the warmer indoor exhaust air enters the secondary air passage of the dry sensible heat regenerator (101), while the cooler outdoor fresh air enters its primary air passage. After being preheated by the indoor exhaust air on the secondary side in the primary air passage, the outdoor fresh air continues to enter the primary air passage of the heat pipe-assisted thermoelectric heat recovery system, absorbing the condensation heat released by the condensation section of the first flat plate heat pipe array (202), and is then reheated before being sent indoors. Meanwhile, the exhaust air from the outlet of the secondary air passage of the dry sensible heat regenerator (101) then enters the secondary air passage of the heat pipe assisted thermoelectric heat recovery system, and is further cooled by the evaporation section of the second flat plate heat pipe array (203) before being discharged outdoors.

[0029] This invention first utilizes an indirect evaporative cooling system to recover energy from indoor exhaust air and pre-treat fresh air to save energy. Then, it uses a flat-plate heat pipe-assisted thermoelectric cooling / heating technology to actively regulate the temperature and humidity of the fresh air. By organically coupling these three technologies, a highly efficient and energy-saving composite fresh air treatment system is constructed. This system reduces the energy consumption of the fresh air system while ensuring indoor air quality and thermal comfort, and achieves efficient recovery of exhaust air energy and precise control of supply air temperature and humidity.

[0030] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. An intelligent fresh air system with indirect evaporative cooling and thermoelectric heat recovery, characterized in that: It includes an indirect evaporative cooling system with air channels in series and a heat pipe-assisted thermoelectric heat recovery system, a closed-loop cooling water circuit through a spray device and a water tank, as well as sensors for signal acquisition and control components for regulation.

2. The intelligent fresh air system with indirect evaporative cooling and thermoelectric heat recovery according to claim 1, characterized in that: The indirect evaporative cooling system includes an indirect evaporative cooler (101), a first spray device (102), a first variable frequency fan (103), a second variable frequency fan (104), and a first variable frequency water pump (105); The first variable frequency fan (103) is installed at the inlet of the primary air channel of the indirect evaporative cooler (101) and connected to the outdoor fresh air inlet; the second variable frequency fan (104) is installed at the inlet of the secondary air channel of the indirect evaporative cooler and connected to the indoor exhaust outlet; the first spray device (102), the first variable frequency water pump (105) and the water tank are connected by water pipes; in the summer operation mode, the first spray device (102) is used to spray circulating water into the wet channel of the indirect evaporative cooler (101), so that a water film is formed on the heat exchange wall of the wet channel, and the secondary air flowing through the wet channel exchanges heat and mass with the water film, and the evaporation heat absorption effect of water is used to reduce the temperature of the heat exchange wall, thereby realizing the indirect cooling of the primary air in the dry channel; the circulating water after spraying flows back to the water tank through the return water pipe installed at the bottom of the box, realizing recycling; the outlets of the primary air channel and the secondary air channel of the indirect evaporative cooler (101) are respectively connected to the inlet of the primary air channel and the inlet of the secondary air channel of the heat pipe assisted thermoelectric heat recovery system.

3. The intelligent fresh air system with indirect evaporative cooling and thermoelectric heat recovery according to claim 1, characterized in that: The heat pipe assisted thermoelectric heat recovery system includes two sets of housings, multiple sets of heat pipe assisted thermoelectric modules connected in series, a primary air channel, a secondary air channel, a second spray device (205), and a second variable frequency water pump (206). The multiple sets of heat pipe assisted thermoelectric modules connected in series are straddling the two sets of housings. The heat pipe assisted thermoelectric modules are filled with heat insulation cotton around their perimeter and the portion located between the two housings, and are sealed with heat insulation aluminum foil tape to reduce heat exchange with the outside air. The second spray device (205), the second variable frequency water pump (206), and the water tank are connected by water pipes. In the summer operation mode, the second spray device (205) sprays circulating water into the secondary air channel of the heat pipe assisted thermoelectric heat recovery system, so that the circulating water and the secondary air can exchange heat and mass. The evaporation and heat absorption of water are used to reduce the temperature of the secondary air, thereby strengthening the heat exchange between the second flat plate heat pipe array (203) in the heat pipe assisted thermoelectric module and the secondary air. The circulating water after spraying flows back to the water tank through the return water pipe set at the bottom of the tank to realize recycling.

4. The intelligent fresh air system with indirect evaporative cooling and thermoelectric heat recovery according to claim 3, characterized in that: Each heat pipe-assisted thermoelectric module includes a thermoelectric module (201), a first flat plate heat pipe array (202), a second flat plate heat pipe array (203), and fins (204) arranged on the flat plate heat pipe array; one end of the first flat plate heat pipe array (202) and the second flat plate heat pipe array (203) are respectively attached to the cold and hot ends of the thermoelectric module (201); the other ends of the first flat plate heat pipe array (202) and the second flat plate heat pipe array (203) extend into the primary air channel and the secondary air channel of the heat pipe-assisted thermoelectric heat recovery system, respectively; the thermoelectric module (201) realizes the switching between cooling and heating modes by changing the direction of the input current, and realizes the active regulation of air temperature by adjusting the magnitude of the input current; the first flat plate heat pipe array (202) and the second flat plate heat pipe array (203) are used to transfer heat between the cold and hot ends of the thermoelectric module (201) and enhance the heat exchange between the thermoelectric module and the air channel.

5. The intelligent fresh air system with indirect evaporative cooling and thermoelectric heat recovery according to claim 4, characterized in that: The first flat plate heat pipe array (202) and the second flat plate heat pipe array (203) are both provided with straight fins (204) on the surface of the air channel section, which are used to expand the heat exchange area between the flat plate heat pipe array and the air and enhance the heat exchange on the air side.

6. The intelligent fresh air system with indirect evaporative cooling and thermoelectric heat recovery according to claim 1, characterized in that: In the control components, a first temperature and humidity sensor (301) and a second temperature and humidity sensor (302) are respectively installed at the inlet of the primary and secondary air channels of the indirect evaporative cooler; a third temperature and humidity sensor (303) and a fourth temperature and humidity sensor (304) are respectively installed at the inlet of the primary and secondary air channels of the heat pipe-assisted thermoelectric heat recovery system; a fifth temperature and humidity sensor (305) and a sixth temperature and humidity sensor (306) are respectively installed at the outlet of the primary and secondary air channels; a first temperature sensor (308) and a first flow meter (310) are installed at the inlet of the first spray device (102) of the indirect evaporative cooling system. A second temperature sensor (307) and a second flow meter (309) are installed at the inlet of the second spray device (205) of the heat pipe assisted thermoelectric heat recovery system; an ammeter (311) is connected to the thermoelectric module (201); the first temperature and humidity sensor to the sixth temperature and humidity sensor, the first temperature sensor (307), the second temperature sensor (308), the first flow meter (309), the second flow meter (310) and the ammeter (311) are all connected to the controller (312); the controller is configured with current regulation logic, and adjusts the input current of the thermoelectric module and the number of thermoelectric modules in operation according to the temperature and humidity signal, so as to regulate the fresh air supply temperature.

7. The intelligent fresh air system with indirect evaporative cooling and thermoelectric heat recovery according to claim 2, characterized in that: The indirect evaporative cooler (101) has a cross-flow structure. The interior of the indirect evaporative cooler (101) is divided into a dry channel that does not mix with each other as a primary air channel and a wet channel as a secondary air channel. The dry channel circulates outdoor fresh air, and the wet channel circulates indoor exhaust air, so that the exhaust air can pre-cool or preheat the fresh air under the action of the spray water of the first spray device (102).

8. The intelligent fresh air system with indirect evaporative cooling and thermoelectric heat recovery according to claim 2, characterized in that: During summer operation, the controller turns on all the spray devices and water pumps in the indirect evaporative cooling system to enhance the heat exchange between the condensing section of the second flat plate heat pipe array (203) in the heat pipe auxiliary thermoelectric module and the secondary air using the spray water. During winter operation, the controller turns off all the spray devices and water pumps in the indirect evaporative cooling system, and the indirect evaporative cooler is used only as a dry sensible heat regenerator to recover the waste heat from the indoor exhaust air.

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