Submerged microchannel sensible heat air handling system

Abstract

This invention discloses an immersion microchannel sensible heat air handling system, belonging to the field of HVAC technology, aiming to solve the problems of complex structure, high energy consumption, and high cost of existing compressed air handling systems. The system does not include a compressor and comprises: a heat exchange tank for containing the heat exchange fluid; a parallel flow microchannel heat exchanger assembly, which is completely immersed in the heat exchange fluid in the heat exchange tank, the heat exchanger assembly consisting of individual heat exchanger units including a manifold and multiple multi-channel microchannel flat tubes; a low-grade heat source water supply unit for supplying the heat exchange fluid to the heat exchange tank; an air drive device for driving the air to be treated to flow inside the microchannels of the flat tubes; and a fluid drive device for driving the circulation of the heat exchange fluid. When the air to be treated flows inside the microchannels of the flat tubes, it exchanges sensible heat with the heat exchange fluid outside the flat tubes through the tube walls. This invention has a simple structure, low operating energy consumption and cost, and can efficiently utilize low-grade heat sources.

Description

Technical Field

[0001] This invention relates to the field of heating, ventilation and air conditioning technology, and in particular to an immersion microchannel sensible heat air handling system. Background Technology

[0002] Utilizing geothermal energy for building heating and cooling is a crucial technological approach to achieving building energy conservation. Current mainstream technologies primarily rely on reverse Carnot cycle compression systems, such as ground source heat pumps. These systems transfer heat through a phase change cycle of refrigerant in the evaporator, compressor, condenser, and throttling device. However, this technology has inherent drawbacks: First, the system structure is complex, containing multiple precision components such as compressors and throttling valves, leading to high manufacturing and maintenance costs and a relatively high failure rate. Second, operation relies on high-grade electrical energy to drive the compressor, resulting in a long energy conversion path and multiple heat exchange temperature differences, limiting overall energy efficiency, especially with severe performance degradation at low temperatures. Third, the refrigerants used generally have high global warming potential, posing a risk of leakage and environmental threats. Furthermore, this compression-based air conditioning method also negatively impacts indoor environmental health. For example, the systems often employ closed-loop internal circulation, resulting in insufficient fresh air intake and a tendency for indoor pollutant concentrations to accumulate; the low surface temperature of the evaporator during cooling easily leads to condensation, providing a breeding ground for bacteria and mold.

[0003] Although parallel-flow microchannel heat exchangers for gas-liquid heat exchange have been disclosed in the prior art, they are typically used as components (such as condensers or evaporators) in the aforementioned compression refrigeration systems and do not deviate from the overall architecture of the reverse Carnot cycle. Therefore, they fail to fundamentally solve the aforementioned systemic problems. Consequently, the prior art lacks a solution that can eliminate the complex compression cycle and achieve a simplified structure, high efficiency, energy saving, and environmentally friendly direct utilization of ground source energy. Summary of the Invention

[0004] The purpose of this invention is to provide an immersion microchannel sensible heat air handling system, which aims to solve the technical problems of existing ground source utilization systems based on reverse Carnot cycles, such as complex structure, low energy efficiency, and negative impacts on environmental protection and health.

[0005] To achieve the above objectives, this application provides the following solution: In a first aspect, this application provides an immersion microchannel sensible heat air handling system, the system excluding a compressor and comprising: A heat exchange tank is used to hold the heat exchange fluid. The parallel flow microchannel heat exchanger assembly is completely immersed in the heat exchange fluid of the heat exchange tank; the parallel flow microchannel heat exchanger assembly is composed of at least one parallel flow microchannel heat exchanger unit; the parallel flow microchannel heat exchanger unit includes two parallel manifolds and several parallel flat tubes connected between the two manifolds. A low-grade heat source water supply unit is connected to the heat exchange water tank to form a circulation loop for the heat exchange fluid; An air-driven device is used to drive the air to be processed to flow inside the microchannel of the flat tube through the manifold; A fluid drive device for driving the heat exchange fluid to circulate within the circulation loop; When the air to be processed flows inside the flat tube, it exchanges sensible heat with the heat exchange fluid outside the flat tube through the tube wall.

[0006] In some embodiments, the heat exchange fluid is water.

[0007] In some embodiments, the low-grade heat source water supply unit is a ground source side constant temperature water supply unit, which is connected to a ground source heat well or a buried pipe heat exchange device. Alternatively, the low-grade heat source water supply unit may be connected to surface water bodies such as lakes or rivers.

[0008] In some embodiments, the parallel flow microchannel heat exchanger group is formed by connecting several parallel flow microchannel heat exchanger units in parallel along the airflow path.

[0009] In some embodiments, a plurality of the parallel flow microchannel heat exchanger units are arranged in at least two rows in the heat exchange tank, and the parallel flow microchannel heat exchanger units in the latter row are staggered with the parallel flow microchannel heat exchanger units in the former row.

[0010] In some embodiments, the parallel flow microchannel heat exchanger unit is made of aluminum.

[0011] In some embodiments, the flow direction of the heat exchange fluid in the heat exchange tank is cross-current with the overall flow direction of the air to be treated in the flat tube.

[0012] In some embodiments, the air drive device is a variable frequency fan, and the fluid drive device is a variable frequency water pump.

[0013] According to the specific embodiments provided in this application, the following technical effects are disclosed: 1. By adopting a non-compression direct heat exchange architecture, the complex and expensive components such as compressors, condensers, and expansion valves in traditional solutions are eliminated. The system structure is simplified to "heat exchanger group + fan + water pump + geothermal well", which greatly reduces the manufacturing cost, maintenance cost and failure rate of the equipment, while fundamentally eliminating the environmental risk of refrigerant leakage.

[0014] 2. By employing a parallel-flow microchannel heat exchanger combined with an immersion design, a large heat exchange area and highly efficient direct air-to-water heat exchange performance are achieved, making it particularly suitable for conditions with small temperature differences. The system avoids losses from multiple energy conversions and multiple media heat transfers, requiring only the drive of a fan and water pump, resulting in high energy utilization efficiency and a significant reduction in operating energy consumption.

[0015] 3. With fresh air processing as its core function, it continuously introduces fresh outdoor air, effectively diluting indoor pollutants. Because it uses sensible heat exchange, the heat exchanger surface remains dry, inhibiting the growth of bacteria and mold. Simultaneously, the simple system structure and the use of water as the heat exchange medium result in significantly lower consumption of negative oxygen ions compared to traditional air conditioners, helping to maintain the natural activity and freshness of indoor air. The supply air temperature changes gradually, avoiding a strong draft and providing a more comfortable experience. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of a parallel flow microchannel heat exchanger assembly in one embodiment of this application; Figure 2 This is a schematic diagram of the structure of a single parallel flow microchannel heat exchanger unit in one embodiment of this application; Figure 3 This is a schematic cross-sectional view of a flat tube in one embodiment of this application; Figure 4 This is a schematic diagram of the structure of an immersion microchannel sensible heat air handling system in one embodiment of this application. Detailed Implementation

[0018] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0019] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0020] This application aims to provide an immersion microchannel ground-source sensible heat air handling system. Its core objective is to address a series of technical problems inherent in existing reverse Carnot cycle-based compression systems, including complex structure, high energy consumption, environmental risks, and negative impacts on indoor air quality. The technical solution of this application achieves efficient, direct, and healthy utilization of ground-source energy through a non-compressible direct heat exchange architecture.

[0021] This application provides an immersion microchannel sensible heat air handling system, characterized in that it does not include a compressor. The system includes a heat exchange tank for containing the heat exchange fluid, and is equipped with at least one fluid inlet and at least one fluid outlet, providing a stable and controllable physical space for the core heat exchange process. By setting up such a dedicated container, the core heat exchange components are ensured to be completely submerged, and a basis for the circulation and management of the heat exchange fluid is provided.

[0022] Inside the hot water tank, a parallel-flow microchannel heat exchanger assembly is installed, completely submerged in the heat exchange fluid. This "submerged" design is one of the keys to achieving efficient heat exchange. Compared to traditional air coolers or radiators, completely submerging the entire heat exchanger assembly ensures full contact between the outer surface of the heat exchanger and the heat exchange fluid, greatly increasing the effective heat exchange area and avoiding the thermal resistance caused by air as an intermediate medium, thus laying the structural foundation for efficient direct heat exchange.

[0023] like Figure 1 As shown, the parallel flow microchannel heat exchanger assembly consists of at least one parallel flow microchannel heat exchanger unit. Specifically, as... Figure 2 As shown, each unit includes two parallel manifolds (upper and lower manifolds) and several parallel flat tubes connecting these two manifolds. Air enters through one manifold, is evenly distributed into the flat tubes, undergoes heat exchange, and then converges and flows out through the other manifold. This structural design ensures that air flows through the heat exchange core in a parallel manner, reducing flow resistance on the air side and facilitating high-volume, low-energy air handling.

[0024] Preferably, the flat tube is designed as a multi-channel microchannel flat tube. Inside the flat tube, multiple parallel microchannels are arranged. The air to be processed flows within these microchannels. The purpose of this microchannel structure design is to significantly increase the specific surface area of ​​air contact with the tube wall by dividing the total airflow channel into a large number of tiny channels, while simultaneously reducing the distance heat must travel from the air core to the tube wall. This significantly enhances convective heat transfer on the air side, which is a core technical means to achieve efficient heat transfer on the side of air, a fluid with low thermal conductivity.

[0025] The system also includes a low-grade heat source water supply unit, which is connected to the fluid inlet and outlet of the hot water exchange tank to form a circulation loop for the heat exchange fluid. This unit is the system's energy source, utilizing low-grade energy with a relatively constant temperature found in nature, replacing the high-grade electrical energy consumed by the compressor in traditional air conditioning systems. By continuously supplying a constant-temperature heat exchange fluid, the system ensures the stability of the temperature inside the hot water exchange tank, providing a reliable temperature reference for the sensible heat exchange process.

[0026] To enable the two fluids (air and heat exchange fluid) to flow within the system, separate air-driven and fluid-driven devices are installed. The air-driven device, for example... Figure 4 The fan shown is used to drive the air to be treated to flow within the microchannels of the flat tube. Fluid-driven devices, such as... Figure 1 The water pump shown is used to drive the heat exchange fluid to circulate within the loop. These two drive units are the core power source for the system's operation, but their energy consumption is extremely low compared to driving the compressor.

[0027] The working principle of this system is that when the air to be processed flows inside the microchannels of the flat tube under the drive of the air-driven device, it exchanges sensible heat with the heat exchange fluid circulating outside the flat tube, driven by the fluid-driven device, through the tube wall. Heat is directly transferred from one fluid to another through the thin tube wall, without a refrigerant phase change process or intermediate heat exchange links, resulting in the shortest energy transfer path and high efficiency. This direct and efficient sensible heat exchange solves the problem of low efficiency caused by long energy conversion chains and multiple heat transfer links in existing technologies.

[0028] In a preferred embodiment, the heat exchange fluid is water. Water is chosen as the heat exchange fluid because it has advantages such as high specific heat capacity, good thermal conductivity, non-toxicity, harmlessness, low cost, and easy availability. In most application scenarios, water is an ideal medium for achieving efficient, safe, and economical heat exchange.

[0029] Furthermore, low-grade heat source water supply units can be implemented in various specific forms.

[0030] In a preferred embodiment, it is a ground-source constant-temperature water supply unit, which is connected to a ground-source heat well or a buried pipe heat exchange device. Utilizing the characteristic that the deep soil or groundwater maintains a relatively constant temperature (e.g., around 18°C) year-round, a relatively stable and sustainable cold source (summer) or heat source (winter) can be provided to the system, greatly improving the system's energy efficiency and operational economy.

[0031] In another alternative implementation, the low-grade heat source water supply unit is connected to a surface water body such as a lake or river. For buildings located near large bodies of water, using surface water (especially its deep water) as a heat source can also provide a stable and low-cost heat exchange fluid. This approach expands the applicability of the invention, enabling it to utilize different natural resources in a site-specific manner.

[0032] To accommodate different airflow requirements, a parallel flow microchannel heat exchanger assembly can be formed by connecting several individual parallel flow microchannel heat exchangers in parallel along the airflow path. For example... Figure 1 As shown, by stacking multiple heat exchanger units in parallel, the air handling capacity of the system can be easily expanded while maintaining low airflow resistance. This modular design not only facilitates manufacturing and installation but also provides convenience for system customization and future expansion.

[0033] Based on the parallel connection described above, a more optimized arrangement is as follows: Figure 3 Inside the heat exchanger assembly shown, several parallel-flow microchannel heat exchanger units are arranged in at least two rows within the heat exchange tank, with the units in the latter row staggered from those in the former. This staggered arrangement aims to actively disrupt the laminar boundary layer as the heat exchange fluid (water) flows through the heat exchanger assembly. When the water flows past the front row of units, it directly impacts the staggered units in the latter row, generating stronger turbulence and disturbances. This significantly enhances the convective heat transfer coefficient on the water side, further improving the overall heat exchange efficiency of the system.

[0034] In a preferred embodiment, the parallel flow microchannel heat exchanger unit is made of aluminum. Aluminum is used to manufacture the heat exchanger because it has excellent thermal conductivity, reducing the thermal resistance of the tube wall; furthermore, aluminum is lightweight, easy to process into complex microchannel structures through extrusion and welding processes, and relatively inexpensive. This makes it possible to manufacture a lightweight, efficient, high-strength, and airtight integrated heat exchanger.

[0035] To maximize heat exchange efficiency, the relative flow pattern of the two fluids is crucial. In a preferred embodiment of this application, the flow direction of the heat exchange fluid in the heat exchange tank is cross-current and counter-current to the overall flow direction of the air to be treated in the flat tube. That is, the flow path of the heat exchange fluid in the heat exchange tank is a circulation path. The flow direction of the heat exchange fluid on part of the path intersects with the flow direction of the air to be treated (e.g., perpendicular, i.e., the flow direction of the heat exchange fluid is perpendicular to the flat tube), and the flow direction of the heat exchange fluid on another part of the path is opposite to the flow direction of the air to be treated (i.e., the flow direction of the heat exchange fluid is parallel to the flat tube).

[0036] To achieve intelligent regulation and energy-saving operation of the system, in a preferred embodiment, the air drive device is a variable frequency fan, and the fluid drive device is a variable frequency water pump. Replacing traditional fixed frequency equipment with variable frequency equipment allows for flexible adjustment of air and water flow rates according to actual load requirements, avoiding energy waste caused by over-powered systems operating under partial load conditions. This forms the technical foundation for achieving on-demand supply and efficient operation of the system.

[0037] Based on the aforementioned variable frequency drive (VFD) device, this application also provides a closed-loop control system. This system additionally includes a temperature sensor located downstream of the airflow in the parallel flow microchannel heat exchanger assembly, and a controller. The controller adjusts the operating frequency of the variable frequency fan and / or variable frequency water pump based on the difference between the temperature sensor reading and a preset target temperature. In this way, the system can automatically and accurately maintain the outlet air temperature at the set value, achieving a leap from manual adjustment to automatic constant temperature control. This not only improves user comfort but also helps the system operate in a highly efficient and energy-saving state.

[0038] To further enhance heat transfer, the microstructure of the flat tube has also been optimized. In a preferred embodiment, the wall thickness of the flat tube is less than 2 mm. Thinner tube walls mean lower thermal resistance, allowing heat to be transferred more quickly from the air inside the tube to the water outside. This is a direct means of improving heat transfer efficiency while ensuring structural strength. These specific, optimized dimensional parameters collectively ensure that the maximum heat transfer surface area and the minimum thermal resistance are achieved within a limited structural space. This allows for a high heat transfer coefficient exceeding 100 W / (㎡·K) even with a very small temperature difference between the air and water, which is the core performance guarantee that this invention can replace traditional compression systems.

[0039] The present invention has the following technical effects: 1. By adopting a non-compression direct heat exchange architecture, the complex and expensive components such as compressors, condensers, and expansion valves in traditional solutions are eliminated. The system structure is simplified to "heat exchanger group + fan + water pump + geothermal well", which greatly reduces the manufacturing cost, maintenance cost and failure rate of the equipment, while fundamentally eliminating the environmental risk of refrigerant leakage.

[0040] 2. By employing a parallel-flow microchannel heat exchanger combined with an immersion design, a large heat exchange area and highly efficient direct air-to-water heat exchange performance are achieved, making it particularly suitable for conditions with small temperature differences. The system avoids losses from multiple energy conversions and multiple media heat transfers, requiring only the drive of a fan and water pump, resulting in high energy utilization efficiency and a significant reduction in operating energy consumption.

[0041] 3. With fresh air processing as its core function, it continuously introduces fresh outdoor air, effectively diluting indoor pollutants. Because it uses sensible heat exchange, the heat exchanger surface remains dry, inhibiting the growth of bacteria and mold. Simultaneously, the simple system structure and the use of water as the heat exchange medium result in significantly lower consumption of negative oxygen ions compared to traditional air conditioners, helping to maintain the natural activity and freshness of indoor air. The supply air temperature changes gradually, avoiding a strong draft and providing a more comfortable experience.

[0042] In summary, compared to existing central air conditioning systems, this invention significantly reduces both hardware manufacturing costs and daily operating costs. Specifically, compared to existing central air conditioning systems, this invention reduces hardware manufacturing costs by 80% and energy consumption during daily use by more than 60%.

[0043] The following is a more detailed description of the immersion microchannel sensible heat air handling system provided in this application through a specific embodiment.

[0044] In one specific embodiment, an immersion microchannel ground-source sensible heat air handling system is provided. Its core principle is to utilize geothermal water at approximately 18°C ​​as a heat source and cool or heat source. Air flowing through the heat exchanger is directly cooled or heated via a highly efficient heat exchanger assembly with a microchannel structure, completely submerged in the water, thus achieving direct sensible heat exchange without a compressor. The system mainly includes a water exchange tank externally insulated, a parallel-flow microchannel heat exchanger assembly submerged in the tank, a geothermal-side constant-temperature water supply unit (including a water pump and piping) connected to the geothermal well, and an air drive unit (including a filter, fan, and ductwork).

[0045] In this embodiment, the heat exchanger assembly consists of 10 aluminum parallel-flow microchannel heat exchanger units stacked in parallel. Each unit includes an upper manifold and a lower manifold, as well as 200 flat tubes connected between these two manifolds, forming a flat tube array. Air enters from the manifold interface on one side, is distributed by the manifold, flows parallel through the 200 flat tubes, and finally converges in the manifold on the other side, exiting from the manifold interface at the other end.

[0046] Each flat tube is extruded from aluminum, with a cross-sectional dimension of 42mm × 2mm and a wall thickness of less than 2mm. Internally, it is divided by ribs and has 33 parallel microchannels, each approximately 0.87mm wide, within which the air to be processed flows. This precise microstructural design is key to achieving efficient heat exchange.

[0047] In this embodiment, the air to be processed is driven by a fan, first passing through a filter to remove impurities, and then entering through a manifold on one side of the heat exchanger assembly. It is then evenly distributed into the microchannels of all the flat tubes in all the individual units. Simultaneously, 18°C ​​constant-temperature water from a geothermal source is driven by a water pump, entering from the bottom of the heat exchange tank and flowing upwards, completely submerging and flowing through the entire exterior of the heat exchanger assembly. The water flow direction is perpendicular to the mainstream airflow direction, flowing in a counter-current manner. The heat-exchanged air is collected through a manifold on the other side and then discharged; while the water, having completed heat exchange with the air, flows back to the geothermal well from the overflow port at the top of the tank, releasing or absorbing heat before recirculating, forming a closed loop.

[0048] The system operates under two typical conditions. In summer cooling mode, the geothermal well provides constant-temperature water at 18°C, which is pumped into the heat exchange tank. Outdoor air at, for example, 40°C, is drawn in by a fan and flows through the internal microchannels of the heat exchanger assembly. The hot air rapidly transfers heat to the 18°C ​​low-temperature water flowing outside the flat tubes, significantly reducing the air temperature to approximately 20°C before being delivered indoors, thus providing cooling. In winter heating mode, the geothermal well also provides constant-temperature water at 18°C. Outdoor air at, for example, -10°C, absorbs heat from the 18°C ​​"high-temperature" water outside the tubes as it flows through the microchannels. It is then heated to approximately 16°C by the flat tube walls before being delivered indoors, providing heating. This embodiment features a simple system structure, completely eliminating the need for a compressor. Under typical summer / winter operating conditions, the system can process fresh air to a comfortable supply air temperature with extremely low energy consumption (consuming only the electricity of the fan and water pump). The measured heat transfer coefficient of the system exceeds 100 W / (m²). 2 With a theoretical seasonal energy efficiency coefficient of over 6.0, it is economical and environmentally friendly to operate.

[0049] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0050] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. An immersed microchannel sensible heat air handling system characterized by, The system does not include a compressor and includes: A heat exchange tank is used to hold the heat exchange fluid. The parallel flow microchannel heat exchanger assembly is completely immersed in the heat exchange fluid of the heat exchange tank; the parallel flow microchannel heat exchanger assembly is composed of at least one parallel flow microchannel heat exchanger unit; the parallel flow microchannel heat exchanger unit includes two parallel manifolds and several parallel flat tubes connected between the two manifolds. A low-grade heat source water supply unit is connected to the heat exchange water tank to form a circulation loop for the heat exchange fluid; An air-driven device is used to drive the air to be processed to flow inside the microchannel of the flat tube through the manifold; A fluid drive device for driving the heat exchange fluid to circulate within the circulation loop; When the air to be processed flows inside the flat tube, it exchanges sensible heat with the heat exchange fluid outside the flat tube through the tube wall.

2. The submerged microchannel sensible heat air handling system according to claim 1, wherein, The heat exchange fluid is water.

3. The submerged microchannel sensible heat air handling system according to claim 1, wherein, The low-grade heat source water supply unit is a ground source side constant temperature water supply unit, which is connected to a ground source heat well or a buried pipe heat exchange device. Alternatively, the low-grade heat source water supply unit may be connected to surface water bodies such as lakes or rivers.

4. The submerged microchannel sensible heat air handling system according to claim 1, wherein, The parallel flow microchannel heat exchanger group is composed of several parallel flow microchannel heat exchanger units connected in parallel along the airflow path.

5. The submerged microchannel sensible heat air handling system according to claim 4, wherein, Several parallel flow microchannel heat exchanger units are arranged in at least two rows in the heat exchange tank, and the parallel flow microchannel heat exchanger units in the latter row are staggered with the parallel flow microchannel heat exchanger units in the former row.

6. The submerged microchannel sensible heat air handling system according to claim 1, wherein, The parallel flow microchannel heat exchanger unit is made of aluminum.

7. The submerged microchannel sensible heat air handling system according to claim 1, wherein, The flow direction of the heat exchange fluid in the heat exchange tank is in a cross-current counter-current with the overall flow direction of the air to be treated in the flat tube.

8. The submerged microchannel sensible heat air handling system according to claim 1, wherein, The air drive device is a variable frequency fan, and the fluid drive device is a variable frequency water pump.

9. The submerged microchannel sensible heat air handling system according to claim 1, wherein, The flat tube is a multi-channel flat tube formed by high-temperature extrusion.

10. The submerged microchannel sensible heat air handling system according to claim 9, wherein, The wall thickness of the flat tube is less than 2 mm.

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