Heating and refrigerating method adopting secondary loop air-conditioning heat pump system
Technical Field
The invention belongs to an air conditioning system of an electric automobile, and particularly relates to a heating and refrigerating method adopting a secondary loop air conditioning heat pump system.
Background
In consideration of global warming and carbon dioxide emission, motor vehicle emission regulations are becoming stricter and new energy electric vehicles are becoming a necessary trend. As the greenhouse effect is more and more serious, the replacement of a novel refrigerant ODP less than or equal to 150 in the air conditioner of the new energy automobile is a common focus of attention. The following table is a potential refrigerant comparison. It can be seen that the refrigerants have different degrees of flammability, except for carbon dioxide, which is not flammable. At present, the problem of serious leakage of the carbon dioxide exists in the air conditioning system due to the problem of high pressure of the carbon dioxide, so that the carbon dioxide refrigerant is limited in practical use. When other flammable refrigerants are used, the leakage problem needs to be solved, and the leakage problem is mainly solved according to the situation that once the leakage occurs, the leakage cannot affect passengers in the passenger compartment.
Table 1 comparison of refrigerants with replacement potential
The secondary loop system is utilized to ensure that the refrigerant loop does not directly contact with the passenger cabin, but the temperature of the air in the air conditioning box is controlled by the cooling liquid, so that the refrigerant can be effectively prevented from entering the passenger cabin when the refrigerant leaks, and if a fire source exists in the passenger cabin, the personal safety of personnel in the passenger cabin can be avoided.
Meanwhile, the power system of the electric automobile is driven by the battery, but the battery is particularly sensitive to temperature when working, and the battery performance is affected when the temperature is too high or too low. The operating range of the battery is typically: 10-30 ℃.
FIG. 1 shows a schematic diagram of cooling and heating of batteries and electronic devices in a temperature range (references Weustenfeldt TA, Bauer-Kugelmann W, Menken J C, et al. Since heat generation in electronic equipment is high, temperature control is always required for cooling, and if the waste heat of the electronic equipment can be recovered and utilized in winter, the utilization rate of energy is also improved.
Fig. 2 is a diagram of a direct refrigeration system commonly used in the prior art, in which 1 is an air conditioning cabinet, 2 is a heater of the air conditioning cabinet, 3 is a cooler of the air conditioning cabinet, 4 is an expansion valve, 5 is a three-way valve, 6 is a compressor, and 7 is an outdoor heat exchanger. The refrigerant directly enters a cooler in the air-conditioning box to exchange heat with air. If the refrigerant is flammable, the refrigerant of the air conditioning box directly contacts with the passenger cabin and is diffused into the passenger cabin once leakage occurs, and life threat is caused to passengers.
Disclosure of Invention
The invention relates to a secondary loop air-conditioning heat pump system, which is characterized in that on one hand, aiming at the situation that most of refrigerants are flammable refrigerants when the refrigerants of an air-conditioning system of an electric automobile are replaced, a secondary cooling liquid loop is utilized to isolate a refrigerating system from a passenger cabin, and if the flammable refrigerants are leaked, the refrigerants cannot enter the safety of passengers in the passenger cabin in a carriage crisis. On the other hand, since the power system of the electric vehicle is driven by the battery, the temperature has a great influence on the performance of the battery, and the battery is controlled by the form of the secondary cooling liquid, so that the battery can exert the best performance when in operation. Meanwhile, refrigeration, heating, single evaporator defrosting and multi-evaporator defrosting can be realized by switching a four-way valve and a three-way valve in secondary cooling liquid.
The system design scheme of the invention comprises the following components:
(1) a refrigerant circuit: the plate-type condenser comprises a hot end, a high-temperature high-pressure gas refrigerant is changed into a high-temperature high-pressure liquid refrigerant after the condenser releases heat, and the released heat is transferred to a hot end cooling liquid through a heat exchanger. The low-temperature low-pressure gas-liquid mixed refrigerant is changed into a low-temperature low-pressure gaseous refrigerant after being released with cold energy through the evaporator, and the released cold energy is transmitted to the cold-end cooling liquid through the heat exchanger. The electric compressor absorbs gaseous refrigerant from the outlet of the evaporator, compresses the refrigerant, and discharges the compressed refrigerant to the condenser.
(2) Cold side coolant loop: the cooling liquid loop at the cold end is connected with the evaporator, and the cooling liquid is conveyed to the cooler in the air conditioning box through the pump to control the temperature of the passenger compartment. When the battery needs to be refrigerated, the cooling liquid passes through the battery pack to control the temperature of the battery.
(3) Hot side coolant loop: and a cooling liquid loop at the hot end is connected with a condenser, and the cooling liquid is conveyed to a middle heater of the air conditioning box through a pump to control the temperature of the passenger compartment. When the battery needs to be heated, the cooling liquid passes through the battery pack to control the temperature of the battery.
Further, the compressor in the refrigerant circuit of the secondary circuit air conditioning heat pump system is an electric compressor.
Furthermore, the secondary loop air-conditioning heat pump system comprises an electrically driven water pump, and the hot end cooling liquid loop and the cold end cooling liquid loop respectively complete a completed cycle through the water pump.
Furthermore, an inlet of a throttling device in a refrigerant loop of the secondary loop air-conditioning heat pump system is connected with an outlet of the plate-type condenser, and an outlet of the throttling device is connected with an inlet of the plate-type evaporator.
Furthermore, a secondary loop of the secondary loop air-conditioning heat pump system consists of a first four-way valve, a second four-way valve, a first three-way valve, a second three-way valve, a third three-way valve, a first pump, a second pump, a cooler, a heater, an outdoor radiator and an air-conditioning box, and the refrigeration, heating and dehumidification modes can be realized by switching the positions of the three-way valve or the four-way valve.
Further, when the secondary loop air-conditioning heat pump system is switched to a refrigeration mode, cold-end cooling liquid flows out of the plate-type evaporator, passes through a water pump, a first three-way valve, is cooled indoors, passes through a second three-way valve, cools a battery pack, passes through a second four-way valve and a third three-way valve, cools a motor in the electric automobile, controls temperature, and then returns to a cooling liquid inlet of the plate-type evaporator; the hot end cooling liquid flows out of the plate type condenser, passes through the water pump, passes through the first four-way valve to reach an outdoor radiator, and returns to the inlet of the plate type condenser through the second four-way valve after redundant heat is removed. Thus, in the cooling mode, the hot side and the cold side cooling liquid complete a complete cycle.
Further, when the secondary loop air-conditioning heat pump system is switched into a heating mode, the hot end cooling liquid comes out of the plate type and passes through the water pump and the first four-way valve to reach a heater in the air-conditioning box, and at the moment, after the cooling liquid heats the battery pack for temperature control, the cooling liquid returns to the inlet of the plate type condenser through the second four-way valve; the cold end cooling liquid comes out from the plate evaporator, passes through the first pump, the first tee joint, the first four-way valve, and then passes through the second four-way valve and the third three-way valve, and returns to the cooling liquid inlet of the plate evaporator after the temperature of the motor in the electric automobile is controlled. Thus, the cooling liquid at the hot end and the cooling liquid at the cold end complete a complete cycle under the heating mode.
Furthermore, when the secondary loop air-conditioning heat pump system is switched to a dehumidification mode, single heat exchanger dehumidification and double heat exchanger dehumidification can be realized.
(1) In the dehumidification mode of the single heat exchanger, the path of the hot-end cooling liquid loop is as follows: the hot end cooling liquid comes out of the plate type condenser and passes through a second pump and the first four-way valve to a heater in the air conditioning box, and at the moment, the cooling liquid returns to the inlet of the plate type condenser through the second four-way valve after heating the battery pack; the cold end cooling liquid comes out from the plate evaporator and passes through the water pump and the first three-way valve, at the moment, the cooling liquid completely reaches the cooler in the air-conditioning box, and the cooling liquid returns to the inlet of the plate evaporator through the third three-way valve.
(2) When the double heat exchangers are in a dehumidification mode, the path of the hot-end cooling liquid loop is the same as that of the single heat exchanger in the dehumidification mode, and the difference is that the cold-end cooling liquid loop; the cold end cooling liquid comes out from the plate evaporator and passes through the water pump and the first three-way valve, at the moment, one part of the cooling liquid passing through the first three-way valve is dehumidified by a cooler in the air-conditioning box, the redundant heat is removed by one part of the outdoor radiator, and the two parts of the cooling liquid are converged by the third three-way valve and return to the inlet of the plate evaporator.
The invention has the beneficial effects that: the secondary circuit is utilized to prevent flammable refrigerant from directly contacting with the passenger cabin, so that the danger degree to passengers is reduced when the refrigerant leaks. Meanwhile, the temperature of the battery pack can be controlled by using the liquid cooling form of the secondary loop, and meanwhile, the heat in the electronic equipment can be recovered by using the cooling liquid. The secondary loop air-conditioning heat pump system can realize that one system can control the temperature of a plurality of temperature control points, and is convenient to control and manage.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.
FIG. 1 is a schematic diagram of a battery and electronics for cooling and heating in a temperature range;
FIG. 2 is a schematic diagram of a prior art cooling mode;
FIG. 3 is a schematic diagram of the present invention in a cooling mode in one embodiment;
FIG. 4 is a schematic diagram of the present invention in a heating mode in one embodiment;
FIG. 5 is a schematic diagram of an embodiment of the present invention in a single heat exchanger dehumidification (or defrost) mode;
fig. 6 is a schematic diagram of the present invention in a dual heat exchanger dehumidification (or defrost) mode in one embodiment.
Detailed Description
In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without one or more of these specific details. In other instances, well-known features have not been described in order to avoid obscuring the invention.
In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The following detailed description of the preferred embodiments of the invention, however, the invention is capable of other embodiments in addition to those detailed.
The invention provides a secondary loop air-conditioning heat pump system, as shown in fig. 3, comprising:
the refrigerant loop comprises a compressor 01, a plate type condenser 02, a throttling device 03 and a plate type evaporator 04 which are sequentially connected end to end;
an air-conditioning box 17, which comprises a cooler 12 and a heater 13, wherein one end of the heater 13 is connected with a plate-type condenser 02 and a plate-type evaporator 04 through a first four-way valve 10, a first three-way valve 07 is arranged between the first four-way valve 10 and the plate-type evaporator 04, and the first three-way valve 07 is connected with the cooler 12;
a battery pack 15 connected to the cooler 12 and the heater 13 through a second three-way valve 08, respectively;
one end of the motor 16 is connected with the plate evaporator 04, the other end of the motor is connected with the second three-way valve 08 through the third three-way valve 09, and the remaining port of the third three-way valve 09 is connected with the battery pack 15 through the second four-way valve 11;
an outdoor radiator 14 has one end connected to the first four-way valve 10 and the other end connected to a second four-way valve 11, and the second four-way valve 11 is connected to the plate condenser 02.
In an alternative embodiment of the invention, a first pump 05 is arranged between the first three-way valve 07 and the plate evaporator 04. Further, a second pump 06 is provided between the first four-way valve 10 and the plate condenser 02.
In an alternative embodiment of the invention, the output of the cooler 12 is arranged between the second three-way valve 08 and the third three-way valve 09.
Meanwhile, the invention also provides a heating and refrigerating method adopting the secondary loop air-conditioning heat pump system, which comprises a refrigerating mode, a heating mode, a single heat exchanger dehumidification mode and a double heat exchanger dehumidification mode. The operation of these 4 modes is further described below.
Referring to fig. 3, the process of the cooling mode is: the cooling liquid at the cold end of the plate evaporator 04 sequentially passes through the first three-way valve 07, the cooler 12 and the second three-way valve 08 to the battery pack 15 to cool the battery pack 15, then passes through the second four-way valve 11 and the third three-way valve 09 to cool the motor 16 for temperature control, and then returns to the cooling liquid inlet of the plate evaporator 04; meanwhile, the hot-end cooling liquid of the plate condenser 02 passes through the second pump 06 and the first four-way valve 10 to the outdoor radiator 14, and then passes through the second four-way valve 11 to return to the inlet of the plate condenser 02.
Referring to fig. 4, the process of the heating mode is: the hot end cooling liquid of the plate condenser 02 sequentially passes through a second pump 06, a first four-way valve 10, a heater 13 and a second three-way valve 08 to a battery pack 15 to heat the battery pack 15, and then passes through a second four-way valve 11 to return to an inlet of the plate condenser 02; meanwhile, the cooling liquid at the cold end of the plate evaporator 04 sequentially passes through the first pump 05, the first tee joint 07, the first four-way valve 10 to the outdoor radiator 14, then passes through the second four-way valve 11 and the third three-way valve 09 to cool the motor 16 for temperature control, and then returns to the cooling liquid inlet of the plate evaporator 04;
referring to fig. 5, the process of the single heat exchanger dehumidification mode is: the hot end cooling liquid of the plate condenser 02 sequentially passes through a second pump 06, a first four-way valve 10, a heater 13, a second three-way valve 08 to a battery pack 15 to heat the battery pack 15, and then passes through a second four-way valve 11 to return to an inlet of the plate condenser 02; meanwhile, the cooling liquid at the cold end of the plate evaporator 04 is cooled and controlled by the motor 16 through the first pump 05, the first three-way valve 07, the cooler 12 and the third three-way valve 09, and then returns to the cooling liquid inlet of the plate evaporator 04;
referring to fig. 6, the process of the dual heat exchanger dehumidification mode is: the hot end cooling liquid of the plate condenser 02 sequentially passes through a second pump 06, a first four-way valve 10, a heater 13, a second three-way valve 08 to a battery pack 15 to heat the battery pack 15, and then passes through a second four-way valve 11 to return to an inlet of the plate condenser 02; meanwhile, one part of the cooling liquid at the cold end of the plate evaporator 04 is dehumidified by passing through the first three-way valve 07 to the cooler 12, the other part of the cooling liquid is delivered to the outdoor radiator 14 by passing through the first three-way valve 07 and the first four-way valve 10, and the two parts of the cooling liquid are converged at the third three-way valve 09 and return to the cooling liquid inlet of the plate evaporator 04 after being cooled and controlled by the motor 16.
Due to the adoption of the technical scheme, compared with the dehumidification mode of a single heat exchanger, the dehumidification amount of the single heat exchanger is large, the temperature difference of cooling air is large, and the dehumidification mode of the double heat exchanger and the dehumidification mode of the single heat exchanger can be freely switched by distributing the flow of the cooling liquid through the first three-way valve. In addition, all three-way valves are automatically controlled three-way valves, so that the cooling liquid in the loop can be conveniently opened or closed. All four-way valves can automatically change the direction of the cooling liquid loop.
According to the above description of the embodiments, the secondary circuit heat pump system utilizes three circuits so that the refrigerant circuit does not come into direct contact with the passenger compartment, and there may be an option to add a new type of refrigerant. Through the mode of secondary cooling, the coolant liquid passes through the form of pump delivery, not only can carry out comfort level control to passenger's cabin, also can carry out temperature control to battery package and electronic equipment, realizes that a system controls a plurality of accuse temperature points.
The above description is of the preferred embodiment of the invention. It is to be understood that the invention is not limited to the particular embodiments described above, in that devices and structures not described in detail are understood to be implemented in a manner common in the art; those skilled in the art can make many possible variations and modifications to the disclosed embodiments, or modify equivalent embodiments to equivalent variations, without departing from the spirit of the invention, using the methods and techniques disclosed above. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention are still within the scope of the protection of the technical solution of the present invention, unless the contents of the technical solution of the present invention are departed.