Environment-friendly and safe air conditioning unit for rail vehicle

Abstract

The utility model provides a kind of air conditioning unit for environmental protection safety type rail vehicle, comprising: refrigeration circuit, the refrigeration function of the air conditioning unit is realized, including through refrigeration pipeline full-enclosed connection's compressor, condenser and evaporator, the low WGP weak flammability refrigerant of one-way flow is filled in the refrigeration circuit;Heating element, the heating function of the air conditioning unit is realized.The utility model provides a kind of air conditioning unit for environmental protection safety type rail vehicle, by filling low GWP weak flammability refrigerant in closed refrigeration circuit, using microchannel condenser can reduce filling quantity, reduce cost and energy consumption, and improve the safety and environmental protection of air conditioning unit.

Description

Technical Field

[0001] This utility model relates to the field of air conditioning unit technology, and in particular to an environmentally friendly and safe air conditioning unit for rail vehicles. Background Technology

[0002] With the ecological impact of global warming, the European Union has banned the use of refrigerant R134a in newly approved vehicles since January 1, 2013. Greenhouse gas emissions are to be reduced to 40% by 2030, and emissions of fluorinated greenhouse gases need to be reduced by 90% by 2050 compared to 2015. Therefore, the use of low-GWP refrigerants in tram air conditioning units is imperative.

[0003] For air conditioning units with the same cooling capacity, traditional air conditioning units require more than 30% higher refrigerant charge than the standard recommended charge. Since the refrigerant charge cannot be reduced further, secondary heat exchange technology is needed, leading to a significant increase in cost and energy consumption.

[0004] The air conditioning unit involved in this utility model can effectively solve the above-mentioned defects while meeting environmental protection requirements. Utility Model Content

[0005] To address the deficiencies and problems existing in the prior art, this utility model provides an environmentally friendly and safe air conditioning unit for rail vehicles. By charging a low-GWP, weakly flammable refrigerant into a closed refrigeration circuit, the charging amount can be reduced, costs and energy consumption can be lowered, and the environmental protection and safety of the air conditioning unit can be improved.

[0006] To solve the above-mentioned technical problems, this utility model provides an environmentally friendly and safe air conditioning unit for rail vehicles, which adopts the following technical solution:

[0007] An environmentally friendly and safe air conditioning unit for rail vehicles includes:

[0008] The refrigeration circuit realizes the refrigeration function of the air conditioning unit, including a compressor, condenser and evaporator connected in a fully enclosed manner through refrigeration pipelines, and the refrigeration circuit is filled with a unidirectional flow low GWP weakly flammable refrigerant.

[0009] The heating element enables the air conditioning unit to perform its heating function.

[0010] Furthermore, the condenser is a microchannel heat exchanger with a flat tube structure, and the equivalent diameter of the microchannel is in the range of 10-1000 μm.

[0011] Furthermore, the evaporator has a copper tube and aluminum fin structure, with the length of each tube ranging from 3 to 10 meters.

[0012] Furthermore, the length of each pipe in the evaporator is less than or equal to 5m.

[0013] Furthermore, the heating element is configured as follows:

[0014] When the return air temperature of the indoor fan exceeds the first set temperature, it enters semi-warm operation;

[0015] When the return air temperature of the indoor fan exceeds the second set temperature, it will stop working for a predetermined time and then resume normal control.

[0016] When the return air temperature of the indoor fan drops to the third set temperature, the PTC electric heater 6 enters full heat control.

[0017] Furthermore, after the heating element stops, the indoor fan will continue to run for a predetermined time before stopping.

[0018] Furthermore, the heating element is disposed between the evaporator and the indoor fan.

[0019] Furthermore, it also includes an electrical control box, which is equipped with an arc-extinguishing device.

[0020] Furthermore, the electrical control box is located above the return air vent of the air conditioning unit.

[0021] Furthermore, the refrigeration circuit includes two or more refrigeration systems, at least one of which is a backup system.

[0022] In summary, the environmentally friendly and safe air conditioning unit for rail vehicles provided by this utility model has the following advantages compared with the prior art:

[0023] Reduce the refrigerant charge in the following ways:

[0024] 1. Microchannel condensers consist of flat tubes with an equivalent diameter of 10-1000μm, resulting in high heat exchange efficiency and a smaller internal volume. Compared with traditional tube-fin condensers, the refrigerant capacity of the condenser can be reduced by 20%-50%.

[0025] 2. The refrigerant side pressure drop of the copper tube aluminum fin evaporator is limited to within 30 kPa, and the length of each pipe is 3-10 m. In this project, the length of each pipe is controlled within 5 m, reducing the refrigerant charge by 5%-10%.

[0026] 3. By rationally arranging components, the length of the refrigerant pipeline can be reduced, and unnecessary refrigeration components, such as liquid receivers and gas-liquid separators, can be eliminated, thereby reducing the refrigerant charge by 5%-15%.

[0027] 4. While meeting noise requirements, appropriately increase the air supply volume and condensing air volume, and reduce the heat exchange area of ​​the evaporator and microchannel condenser. Increase the air supply volume by 8-15% and the condensing air volume by 10%-30%.

[0028] Through the above methods, the refrigerant charge is significantly reduced by more than 30%, meeting the refrigerant charge limit required by the EN378 standard, and greatly reducing the manufacturing cost of the unit.

[0029] By using the following components and appropriate control logic, the temperature inside the refrigerant is reduced to prevent it from exceeding the refrigerant's ignition point, thus improving safety:

[0030] Circuit breakers, contactors, and other components are all integrated into the electrical control box. The contactors and other components are equipped with arc-extinguishing devices, and the electrical control box has an IP66 protection rating.

[0031] By employing the above methods, the source of ignition is prevented from being generated, and the indoor temperature is reduced, greatly improving the safety of the air conditioning unit.

[0032] The specific embodiments of this utility model will be described in further detail below with reference to the accompanying drawings. Attached Figure Description

[0033] The accompanying drawings, as part of this utility model, are used to provide a further understanding of the present utility model. The illustrative embodiments and descriptions of the present utility model are used to explain the present utility model, but do not constitute an undue limitation of the present utility model. Obviously, the drawings described below are merely some embodiments; those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0034] In the attached diagram:

[0035] Figure 1 This is a schematic diagram of the layout structure of an air conditioning unit according to the present invention;

[0036] Figure 2 This is a schematic diagram of the control logic of an air conditioning unit according to the present invention;

[0037] In the picture:

[0038] 1. Housing; 2. Outdoor fan; 3. Compressor; 4. Electrical control box; 5. Evaporator; 6. PTC electric heater; 7. Indoor fan; 8. Fresh air filter; 9. Fresh air valve; 10. Mixing air filter; 11. Microchannel condenser; 12. Return air temperature sensor.

[0039] It should be noted that the accompanying drawings and text description are not intended to limit the scope of the present invention in any way, but rather to illustrate the concept of the present invention to those skilled in the art by referring to specific embodiments. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate this utility model, but are not intended to limit the scope of this utility model.

[0041] In the description of this utility model, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0042] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0043] This utility model provides an environmentally friendly and safe air conditioning unit for rail vehicles, including a refrigeration circuit for realizing the refrigeration function of the air conditioning unit. The refrigeration circuit includes a compressor, condenser and evaporator connected in a fully enclosed manner through refrigeration pipelines. The refrigeration circuit is filled with unidirectional R1234fy refrigerant. An indoor fan 7 is installed at the evaporator. A heating element is provided to realize the heating function of the air conditioning unit.

[0044] This utility model provides an environmentally friendly and safe air conditioning unit for rail vehicles, including a housing 1. The housing 1 is divided into an indoor cavity and an outdoor cavity by a partition. Figure 1 As shown, the housing 1 is equipped with a compressor 3, an evaporator 5, and a condenser that are connected in a fully enclosed manner through refrigeration pipes. In this embodiment, the condenser is a microchannel condenser 11. The compressor 3, the microchannel condenser 11, and the evaporator 5 are all welded together by copper pipes (refrigeration pipes).

[0045] The compressor 3 and the condenser are located in the outdoor cavity. An outdoor fan 2 is installed on the top wall of the outdoor cavity of the condenser (the side wall that communicates with the outside) to provide ventilation and heat dissipation for the compressor 3 and the condenser.

[0046] The evaporator 5 is installed inside the indoor cavity, which is connected to the outside. It supplies heat-exchanged air to the inside and regulates the indoor temperature. Preferably, an indoor fan 7 is installed on the side of the evaporator 5, away from the outdoor cavity. The air outlet of the indoor cavity (air conditioning unit) is located below the indoor fan 7. The heat-exchanged air is directly supplied to the indoor (car compartment) through the air outlet to regulate the indoor temperature and achieve indoor temperature comfort.

[0047] The indoor air supply outlet is set on any side wall of the indoor cavity. A fresh air inlet is provided at the fresh air inlet, and a fresh air filter 8 and a fresh air valve 9 are provided at the fresh air inlet. The outside fresh air entering from the fresh air inlet enters the static pressure chamber (not shown in the figure), mixes with the indoor return air, is filtered by the mixing air filter 10, passes through the evaporator 5, and is sent into the room by the indoor fan 7.

[0048] The refrigeration circuit includes components such as compressor 3, microchannel condenser 11, and evaporator 5, which are connected together by copper pipe welding. Refrigerant R1234yf flows unidirectionally through the refrigeration circuit and its components, exchanging heat through forced convection with the indoor fan 7 and outdoor fan 2 to achieve the cooling function of the air conditioning unit and provide cool air to the vehicle interior. In this application, the refrigeration circuit is a fully enclosed system, greatly reducing the risk of refrigerant leakage.

[0049] The refrigeration circuit includes two or more independent refrigeration systems, with at least one refrigeration system serving as a backup system. When any system fails, the other system can operate normally, thus achieving a redundancy design.

[0050] In this embodiment, the refrigeration circuit is charged with R1234yf refrigerant, and the refrigerant charge is reduced through the following technical solution, thereby reducing the cost and improving refrigeration efficiency:

[0051] The microchannel condenser 11 has a flat tube structure, composed of flat tubes with an equivalent diameter of 10-1000μm. It features high heat exchange efficiency and a smaller internal volume, reducing the refrigerant capacity by 20%-50% compared to traditional tube-fin condensers. The equivalent diameter of the flat tubes in the microchannel heat exchanger 11 is determined based on the rated power of the air conditioning unit.

[0052] Evaporator 5 adopts a copper tube aluminum fin evaporator, and the refrigerant pressure drop is limited to within 30 kPa during the operation of the air conditioning unit. The copper tubes are bent to form multiple parallel pipes, and the length of each pipe can be selected from 3 to 10 m. Similarly, the length of each pipe is determined according to the rated power of the air conditioning unit and the internal volume of the indoor cavity. In this embodiment, the length of each pipe is controlled within 5 m, that is, the pipe length is less than or equal to 5 m, which can reduce the refrigerant charge by 5%-10% compared with evaporators with longer pipe lengths.

[0053] Through the reasonable layout of components, such as Figure 1As shown, there are two sets of microchannel condensers 11, which are respectively set on both sides of the outdoor fan 2. The compressor 2 is set between the two sets of condensers 11 on the side closer to the indoor cavity. The electrical control box 4 is set on the side of the indoor cavity closer to the outdoor cavity. The evaporator 5 is set between the electrical control box 4 and the indoor fan 7. This layout reduces the length of the refrigeration pipe through which the refrigerant flows and reduces unnecessary refrigeration components, such as liquid receivers and gas-liquid separators. Compared with the connection method or layout of traditional refrigeration circuits, the refrigerant charge can be reduced by 5%-15%.

[0054] While meeting noise and heat exchange requirements, appropriately increasing the air supply and condensing air volume can reduce the heat exchange area of ​​the evaporator 5 and the microchannel condenser 11. Through numerous experiments, it has been found that by combining different tube lengths of the evaporator 5 and different equivalent diameters of the microchannel condenser 11, the air supply volume of the indoor fan 7 can be increased by 8-15%, and the air volume of the outdoor fan 2 can be increased by 10%-30%.

[0055] By using the above methods, the refrigerant charge can be significantly reduced. With all factors combined, the refrigerant charge is reduced by more than 30% compared to the same specifications of compressor air conditioning units, meeting the refrigerant charge limit required by EN378 standard. This satisfies the refrigeration demand while greatly reducing the manufacturing cost of the unit.

[0056] On the side of the indoor cavity closest to the outdoor cavity, there is a control unit, including an electrical control box 4. Circuit breakers, contactors and other control components are integrated in the electrical control box 4. Based on the real-time temperature inside and outside the vehicle, the control unit controls the operation and stop of the electrical components of the air conditioning unit to realize the control of the cooling and heating functions of the air conditioning unit.

[0057] The electrical control box 4 has an IP66 protection rating and is equipped with an arc-extinguishing device inside. Preferably, the circuit breaker, contactor and other electrical control components are also equipped with arc-extinguishing devices. The electrical control box 4 is located above the return air vent of the air conditioning unit, and the return air is used to dissipate heat from the electrical control box 4. The indoor cavity is located above the return air and supply air vents, thereby preventing the occurrence of ignition sources from the source and reducing the temperature of the indoor cavity to prevent the temperature of the indoor cavity from exceeding the ignition point temperature of R1234fy refrigerant, thus improving safety.

[0058] R1234fy refrigerant flows in one direction in the refrigeration circuit, and there is no four-way valve in the refrigeration circuit. Therefore, the refrigeration circuit of the air conditioning unit can only realize the cooling function, while the heating function is realized through the heating element.

[0059] In this embodiment, the heating element includes at least two separately controllable heating circuits. Each heating circuit is equipped with a PTC electric heater 6, or at least two PTC electric heaters 6 are connected in parallel on the control circuit. Each PTC electric heater 6 can be controlled separately to achieve the regulation of heating amount and the power of the PTC electric heater 6 can be controlled separately, such as full heating, half heating, or even 1 / 3 or 1 / 4 heating.

[0060] The heating function of the air conditioning unit is achieved by the PTC electric heater 6. When heating is required, the refrigerant in the refrigeration circuit stops rotating and does not perform heat exchange. However, the indoor fan 7 runs to deliver the heat generated by the PTC electric heater into the room.

[0061] like Figure 1 As shown, in this embodiment, the PTC electric heater 6 is positioned between the evaporator 5 and the indoor fan 7, and the indoor fan 7 delivers the heat generated by the PTC electric heater 6 into the room. As the temperature of the PTC electric heater 6 increases, the heat exchange capacity of the PTC decreases. During the fault protection test, unlike the rapid temperature rise of tubular resistance wire electric heating, the temperature rise of the PTC electric heater 6 is not significant, but rather slow, far below the limit temperature requirement of A2L refrigerant, thus ensuring the heating demand of the air conditioning unit.

[0062] The heating element includes at least two PTC electric heaters 6, each of which can be individually controlled to meet different temperature requirements. Using PTC electric heaters also reduces the temperature of the evaporator chamber, lowers the risk of combustion of flammable refrigerant, and improves the safety of the air conditioning unit.

[0063] The controller contains control logic for the heating element to control its operating state. Specifically, for example... Figure 2 As shown, the heating element is configured as follows:

[0064] When the return air temperature (detected by a return air temperature sensor 12 installed at the return air inlet) exceeds (or is greater than or equal to) the first set temperature a, the heating element enters semi-heating operation, meaning that the heating element's heat output is controlled to be only half of its rated heat output. This can be achieved by controlling only one PTC electric heater 6 (assuming the heating element includes two PTC electric heaters 6) to enter heating mode, while the other PTC electric heater 6 stops working; or by controlling both PTC electric heaters 6 to heat at only 50% of their rated power. Semi-heating control is a conventional control method in the art and will not be elaborated upon. Any existing or future control method is applicable to this application.

[0065] When the return air temperature exceeds the second temperature b, the temperature at the PTC electric heater 6 is close to and / or exceeds the ignition point of R1234fy refrigerant. Continued heating may cause the residual R1234fy refrigerant in the refrigeration circuit to burn. At this time, both sets of PTC electric heaters 6 stop working to improve heating safety.

[0066] When both sets of PTC electric heaters 6 stop working for a predetermined time, such as 1 minute, the PTC electric heaters 6 resume normal control. "Resuming normal control" means restoring the original heating state; for example, if it was in semi-warm control before stopping heating, it will return to semi-warm control after the predetermined time; if it was in full-heat control before stopping heating, it will return to full-heat control.

[0067] When the return air temperature drops to the third control temperature c (less than or equal to the third control temperature c), the PTC electric heater 6 enters full heat control.

[0068] Once the indoor temperature reaches the set temperature, the air conditioning unit stops heating. The indoor fan 7 continues to run for a predetermined time, such as 3 minutes, before stopping to prevent heat buildup on the PTC heater 6.

[0069] The first set temperature a is taken in the range of 53-57℃, the second set temperature b is taken in the range of 59-62℃, and the third set temperature c is taken in the range of 47-50℃.

[0070] It should be noted that the preset times for the PTC electric heater 6 to stop heating midway and for the air conditioning unit to stop heating are different, but both can be set according to the heating and cooling rates of the PTC electric heater 6 to avoid fluctuations in indoor temperature.

[0071] By installing an electrical control box 4 at the return air vent, an arc-extinguishing device inside the electrical control box 4, a PTC electric heater 6, and configuring corresponding control logic for the PTC electric heater 6, the occurrence of ignition sources is avoided from the source, and the temperature of the indoor cavity is reduced. Even if the refrigerant leaks, it cannot produce combustion, which greatly improves the safety of the air conditioning unit.

[0072] In summary, the environmentally friendly and safe air conditioning unit for rail vehicles provided by this utility model has the following advantages compared with the prior art:

[0073] Reduce the refrigerant charge in the following ways:

[0074] 1. Microchannel condensers consist of flat tubes with an equivalent diameter of 10-1000μm, resulting in high heat exchange efficiency and a smaller internal volume. Compared with traditional tube-fin condensers, the refrigerant charge can be reduced by 20%-50%.

[0075] 2. The refrigerant side pressure drop of the copper tube aluminum fin evaporator is limited to within 30 kPa, and the length of each pipe is 3-10 m. In this project, the length of each pipe is controlled within 5 m, reducing the refrigerant charge by 5%-10%.

[0076] 3. By rationally arranging components, the length of the refrigerant pipeline can be reduced, and unnecessary refrigeration components, such as liquid receivers and gas-liquid separators, can be eliminated, thereby reducing the refrigerant charge by 5%-15%.

[0077] 4. While meeting noise requirements, appropriately increase the air supply volume and condensing air volume, and reduce the heat exchange area of ​​the evaporator and microchannel condenser. Increase the air supply volume by 8-15% and the condensing air volume by 10%-30%.

[0078] Through the above methods, the refrigerant charge is significantly reduced by more than 30%, meeting the refrigerant charge limit required by the EN378 standard, and greatly reducing the manufacturing cost of the unit.

[0079] By using the following components and appropriate control logic, the temperature inside the refrigerant is reduced to prevent it from exceeding the refrigerant's ignition point, thus improving safety:

[0080] Circuit breakers, contactors and other components are all integrated in the electrical control box 4. The contactors and other components are equipped with arc extinguishing devices, and the protection level of the electrical control box 4 can reach IP66.

[0081] By employing the above methods, the source of ignition is prevented from being generated, and the indoor temperature is reduced, greatly improving the safety of the air conditioning unit.

[0082] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Although the present utility model has been disclosed above with reference to a preferred embodiment, it is not intended to limit the present utility model. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present utility model. The implementation schemes in the above embodiments can be further combined or replaced. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present utility model without departing from the scope of the present utility model shall still fall within the scope of the present utility model.

Claims

1. An environmentally friendly and safe air conditioning unit for rail vehicles, characterized in that: include, The refrigeration circuit realizes the refrigeration function of the air conditioning unit, including a compressor, condenser and evaporator connected in a fully enclosed manner through refrigeration pipelines, and the refrigeration circuit is filled with a unidirectional flow low GWP weakly flammable refrigerant. The heating element enables the air conditioning unit to perform its heating function.

2. The environmentally friendly and safe air conditioning unit for rail vehicles as described in claim 1, characterized in that: The condenser is a microchannel heat exchanger with a flat tube structure, and the equivalent diameter of the microchannel is in the range of 10-1000 μm.

3. The environmentally friendly and safe air conditioning unit for rail vehicles as described in claim 1, characterized in that: The evaporator has a copper tube and aluminum fin structure, with the length of each tube ranging from 3 to 10 meters.

4. The environmentally friendly and safe air conditioning unit for rail vehicles as described in claim 3, characterized in that: The length of each pipe in the evaporator is less than or equal to 5m.

5. The environmentally friendly and safe air conditioning unit for rail vehicles as described in claim 1, characterized in that: The heating element is configured such that, When the return air temperature of the indoor fan exceeds the first set temperature, it enters semi-warm operation; When the return air temperature of the indoor fan exceeds the second set temperature, it will stop working for a predetermined time and then resume normal control. When the return air temperature of the indoor fan drops to the third set temperature, the PTC electric heater enters full heat control.

6. The environmentally friendly and safe air conditioning unit for rail vehicles as described in claim 5, characterized in that: After the heating element stops, the indoor fan will continue to run for a predetermined time before stopping.

7. An environmentally friendly and safe air conditioning unit for rail vehicles as described in claim 5 or 6, characterized in that: The heating element is disposed between the evaporator and the indoor fan.

8. The environmentally friendly and safe air conditioning unit for rail vehicles as described in claim 1, characterized in that: It also includes an electrical control box, which contains an arc-extinguishing device.

9. The environmentally friendly and safe air conditioning unit for rail vehicles as described in claim 8, characterized in that: The electrical control box is located above the return air vent of the air conditioning unit.

10. An environmentally friendly and safe air conditioning unit for rail vehicles as described in any one of claims 1 to 6 or 8 to 9, characterized in that: The refrigeration circuit includes two or more refrigeration systems, and at least one of the multiple refrigeration systems is a backup system.

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