Uniform frosting air heat exchanger with heat exchange temperature matched in segmented mode

Abstract

A uniformly frosted air heat exchanger with heat exchange temperature matched in sections is divided into a plurality of flow paths which are connected in parallel, the flow paths are equal in price, in one flow path, the direction of an air inlet is defined as the front, the direction of an air outlet is defined as the rear, heat exchange pipes accounting for 10-15% of the total number of the flow paths are superheat pipes, the first pipe behind the superheat pipes is connected with a refrigerant inlet, and the second pipe behind the superheat pipes is connected with a refrigerant outlet. The subsequent heat exchange pipes are sequentially connected, pass through the heat exchange pipes accounting for about 40% of the flow path header pipe and then are connected with an inlet of a gas-liquid separator, a liquid outlet of the gas-liquid separator is connected with the subsequent residual heat exchange pipes, outlets of the subsequent heat exchange pipes are connected with a gas phase outlet of the gas-liquid separator, and the gas phase outlet of the gas-liquid separator is further connected with an inlet of a superheating pipe; and heat exchange of the whole flow path is completed. According to the air heat exchanger capable of achieving uniform frosting and achieving segmented matching of the heat exchange temperature, the heat exchange efficiency is improved.

Description

Technical Field

[0001] The utility model belongs to a heat exchanger, and relates to an air heat exchanger. Background Art

[0002] An air-cooled heat exchanger is also an evaporator of a refrigeration and air-source heat pump system. The low-temperature refrigerant inside the pipe cools the air outside the pipe, which is a key component affecting the overall energy efficiency. At the same time, water vapor in the air condenses outside the pipe. When the pipe temperature is below 0°C, frost or ice may form on the outside of the heat exchange pipe and fins, resulting in deteriorated heat exchange performance. Improving the heat exchange performance and optimizing the frosting state are the directions for improving the evaporator.

[0003] In the existing air-cooled heat exchanger, the refrigerant at the inlet comes from an expansion valve and is a two-phase fluid, while the outlet is a superheated gas. The humidity at the air inlet is high. After exchanging heat with a small amount of superheated refrigerant, it immediately exchanges heat with the two-phase refrigerant that is affected by the flow resistance and has a lower temperature, resulting in a large amount of water vapor liquefying and frosting, and serious frosting on the pipeline near the air inlet. As the moisture content in the air decreases, the amount of frosting decreases during the subsequent heat exchange process, and the frosting on the pipeline at the air outlet is the least. This leads to two problems. One is that the heat exchange temperature difference at the inlet is large, affecting the cycle energy efficiency. The other is uneven frosting. The defrosting time of the pipeline with serious frosting is long, resulting in the pipeline with less frosting being in an ineffective heating state, seriously reducing the energy efficiency. Therefore, it is very necessary to optimize the heat exchange temperature difference matching and frosting uniformity of the air-cooled heat exchanger. Summary of the Invention

[0004] In order to overcome the deficiency of the low heat exchange efficiency of the existing air-cooled heat exchanger, the utility model provides an air heat exchanger with uniform frosting and segmented matching of heat exchange temperature to improve the heat exchange efficiency.

[0005] The technical solution adopted by the utility model to solve its technical problems is as follows:

[0006] An air heat exchanger with uniform frosting and segmented matching of heat exchange temperature. The air heat exchanger is divided into several parallel flow paths, and each flow path is equivalent. In one of the flow paths, the air inlet direction is defined as the front, and the air outlet direction is defined as the rear. The heat exchange pipes in the front part accounting for 10 - 15% of the total number of flow path pipes are superheated pipes. The first pipe after the superheated pipes is connected to the refrigerant inlet, and the subsequent heat exchange pipes are connected in sequence. After passing through the heat exchange pipes accounting for 35 - 45% of the total number of flow path pipes, it is connected to the inlet of the gas-liquid separator. The liquid outlet of the gas-liquid separator is connected to the subsequent remaining heat exchange pipes. The outlet of the last heat exchange pipe is connected to the gas phase outlet of the gas-liquid separator. The gas phase outlet of the gas-liquid separator is further connected to the inlet of the superheated pipes. The outlet of the superheated pipes is the refrigerant outlet of this flow path, completing the heat exchange of the entire flow path.

[0007] Furthermore, a plurality of flow paths share one gas-liquid separator.

[0008] Furthermore, for the case where a flow path contains multiple rows of heat exchange tubes, the heat exchange tubes are connected vertically first and then horizontally.

[0009] Preferably, a flow path is arranged horizontally with a total of 8 heat exchange tubes. Air flows in from the left and out from the right. The first tube on the left is the superheat tube, and the second tube is the refrigerant inlet connection tube. From this point, refrigerant heat exchange begins. The 2nd - 4th heat exchange tubes are connected in sequence, and the refrigerant flows back and forth in the subsequent heat exchange tubes for heat exchange. Then, the refrigerant with an increased heat dryness after heat exchange enters the gas - liquid separator. The saturated gas therein flows out from the gas phase outlet and no longer participates in the subsequent liquid heat exchange, while the liquid - phase refrigerant flows out from the liquid phase outlet and enters the 5th tube for continued heat exchange. The refrigerant continues to flow back and forth in the subsequent heat exchange tubes for heat exchange until it flows out from the outlet of the 8th tube and becomes saturated gas. The saturated gas at the outlet of the 8th tube is mixed with the gas from the gas phase outlet of the gas - liquid separator and enters the first superheat tube for continued heat exchange until it reaches the superheat state, finally completing the heat exchange process. This solution is an optimal one, and more heat exchange tubes can be set according to needs.

[0010] The beneficial effects of the present utility model are mainly manifested in: improving the connection and arrangement method of the heat exchange tubes inside the air cooler, adding auxiliary components, reducing the temperature difference between air and refrigerant, making the frosting uniform, and significantly improving the heat exchange efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a side view of an air heat exchanger with uniform frosting by segmented matching of heat exchange temperatures, 1. Flow path, 2. Liquid distributor.

[0012] Figure 2 It is a schematic diagram of a single flow path under the traditional connection form.

[0013] Figure 3 It is a heat exchange temperature difference diagram of a single flow path under the traditional connection form.

[0014] Figure 4 It is a schematic diagram of a single flow path under the connection form of the present utility model, 3. Superheat tube, 4. Gas pipe, 5. Liquid pipe, 6. Gas - liquid separator.

[0015] Figure 5 It is a heat exchange temperature difference diagram of a single flow path under the connection form of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] The present utility model will be further described below with reference to the accompanying drawings.

[0017] Refer to Figures 1 to 5, an air heat exchanger with uniform frosting by segmented matching of heat exchange temperature. The air heat exchanger is divided into several parallel flow paths 1, and each flow path is equivalent. In one of the flow paths, with the air inlet direction defined as the front and the air outlet direction as the rear, the heat exchange tubes in the front part accounting for 10 - 15% of the total number of flow path tubes are superheated tubes 3. The first tube after the superheated tube 3 is connected to the refrigerant inlet, and the subsequent heat exchange tubes are connected in sequence. After passing through the heat exchange tubes accounting for 35% - 45% of the total number of flow path tubes, it is connected to the inlet of the gas-liquid separator 6. The liquid outlet of the gas-liquid separator 6 is connected to the subsequent remaining heat exchange tubes, and the refrigerant continues to flow back and forth in the subsequent heat exchange tubes for heat exchange. The outlet of the subsequent heat exchange tubes is connected to the gas phase outlet of the gas-liquid separator 6, and the gas phase outlet of the gas-liquid separator 6 is further connected to the inlet of the superheated tube 3. The refrigerant continues to flow in the superheated tube for heat exchange and flows out from the outlet of the superheated tube 3. The outlet of the superheated tube 3 is the refrigerant outlet of this flow path, completing the heat exchange of the entire flow path.

[0018] Furthermore, a plurality of flow paths 1 share one gas-liquid separator.

[0019] Still further, for the case where a flow path contains multiple rows of heat exchange tubes, the heat exchange tubes are connected first vertically and then horizontally.

[0020] Example: A flow path is arranged horizontally with a total of 8 heat exchange tubes. Air flows in from the left and out from the right. The first tube on the left is the superheated tube, and the second tube is the refrigerant inlet connection tube. From this, the refrigerant starts to exchange heat. The 2nd - 4th heat exchange tubes are connected in sequence, and the refrigerant flows back and forth in the subsequent heat exchange tubes for heat exchange. Then, the refrigerant with a certain increase in heat exchange dryness enters the gas-liquid separator. The saturated gas flows out from the gas phase outlet and no longer participates in the subsequent liquid heat exchange, while the liquid-phase refrigerant flows out from the liquid phase outlet and enters the 5th tube to continue heat exchange until it flows out from the outlet of the 8th tube and becomes saturated gas. Since the gas is excluded, the flow resistance in the subsequent pipeline is reduced, and the wetting condition of the pipe wall is improved, enhancing the heat exchange efficiency and reducing the heat exchange temperature difference. The saturated gas at the outlet of the 8th tube is mixed with the gas at the gas phase outlet of the gas-liquid separator and enters the first superheated tube to continue heat exchange to reach the superheated state, finally completing the heat exchange process. Due to the existence of flow resistance, as Figure 2 and 3 shown, the traditional connection method is connected from right to left, and the two-phase temperature gradually decreases due to the pressure drop, reaching the lowest at the second tube, with the largest heat exchange temperature difference, and the heat transfer and mass transfer with the air temperature are strong. At this point, the air has a high moisture content, thus forming a large amount of frost. The connection method of this solution, as Figure 4 and 5As shown, the second pipe is the refrigerant inlet. The temperature of the refrigerant is relatively high. And due to the improvement of the heat transfer coefficient of pipes 5 to 8, the overall heat transfer temperature difference is relatively low. As a result, the heat transfer temperature difference at the second pipe is much lower than that of the traditional connection method, and it is expected to be reduced by 3 to 5 °C. Thus, the heat and mass transfer intensity is reduced, the frosting degree is reduced, making it close to the frosting degree of the subsequent pipeline, and the frosting uniformity is improved.

[0021] The content described in the embodiments of this specification is only an enumeration of the implementation forms of the utility model concept and is only for illustrative purposes. The protection scope of the present utility model should not be regarded as limited to the specific forms stated in this embodiment. The protection scope of the present utility model also extends to equivalent technical means that can be conceived by those of ordinary skill in the art based on the utility model concept.

Claims

1. An air heat exchanger with uniform frosting and segmented matching of heat exchange temperature, the air heat exchanger is divided into a plurality of parallel flow paths, each flow path is equivalent, and is characterized in that: In one flow path, the air inlet direction is defined as the front, and the air outlet direction is defined as the rear. The heat exchange tubes in the front, which account for 10 to 15% of the total number of tubes in the flow path, are superheat tubes. The first tube after the superheat tube is connected to the refrigerant inlet, and the subsequent heat exchange tubes are connected in sequence. After passing through heat exchange tubes that account for 35 to 45% of the total number of tubes in the flow path, the gas-liquid separator inlet is connected, and the liquid outlet of the gas-liquid separator is connected to the subsequent remaining heat exchange tubes. The subsequent heat exchange tubes are connected in sequence, and the outlet of the last heat exchange tube is connected to the gas phase outlet of the gas-liquid separator, and the gas phase outlet of the gas-liquid separator is further connected to the superheat tube inlet. The superheat tube outlet is the refrigerant outlet of this flow path, completing the heat exchange of the entire flow path.

2. The air heat exchanger with uniform frosting and segmented heat exchange temperature matching according to claim 1, characterized in that: Multiple flow paths share one gas-liquid separator.

3. The air heat exchanger with uniform frosting and segmented matching of heat exchange temperature as claimed in claim 1 or 2, characterized in that: When a flow path includes multiple rows of heat exchange tubes, the heat exchange tubes are connected vertically first and then horizontally.

4. The air heat exchanger with uniform frosting and segmented heat exchange temperature matching according to claim 1 or 2, characterized in that: A flow path is arranged horizontally, with a total of 8 heat exchange tubes. Air flows in from the left and flows out from the right. The first tube on the left is the superheater tube, and the second tube is the refrigerant inlet access tube. Refrigerant heat exchange starts from here. The 2nd to 4th heat exchange tubes are connected in sequence. The refrigerant flows back and forth in the subsequent heat exchange tubes for heat exchange. Then, the refrigerant with increased dryness after heat exchange enters the gas-liquid separator, and the saturated gas therein flows out from the gas phase outlet and no longer participates in the subsequent liquid heat exchange. The liquid refrigerant flows out from the liquid phase outlet and enters the 5th tube to continue heat exchange. The refrigerant continues to flow back and forth in the subsequent heat exchange tubes for heat exchange until it flows out from the 8th tube outlet and becomes a saturated gas. The saturated gas at the 8th tube outlet is mixed with the gas at the gas phase outlet of the gas-liquid separator and enters the first superheater tube to continue heat exchange to reach the superheated state, and finally the heat exchange process is completed.

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