A transcritical carbon dioxide reverse defrosting system and its control method

Abstract

The invention discloses a trans-critical carbon dioxide reverse defrosting system. The system comprises a compressor, a defrosting heat exchanger, a main heat exchanger, an outdoor heat exchanger, anelectronic expansion valve, a four-way reversing valve, a liquid storage device, a three-way valve and a heat regenerator; an outlet of the compressor is connected with an inlet of the defrosting heatexchanger, an outlet of the defrosting heat exchanger is connected with a port D of the four-way reversing valve, and a port A of the four-way reversing valve is connected with a port C of the four-way reversing valve sequentially through the outdoor heat exchanger, a first heat exchange channel of the heat regenerator, the electronic expansion valve and the main heat exchanger; And a port B of the four-way reversing valve is communicated with a first port of the three-way valve through the liquid storage device, a second port of the three-way valve is connected with an inlet of the compressor through a second heat exchange channel of the heat regenerator, and a third port of the three-way valve is directly connected with an inlet of the compressor. The system is simple in structure and convenient to switch, defrosting can be more thorough, less water is accumulated on the surface of the heat exchanger after defrosting is finished, and the secondary frosting speed is reduced.

Description

technical field [0001] The invention belongs to the field of transcritical carbon dioxide air conditioners, and in particular relates to a transcritical carbon dioxide reverse defrosting system and a control method thereof. Background technique [0002] Electric vehicles have very important application prospects because they are not dependent on fossil fuel resources and are environmentally friendly. However, pure electric vehicles do not have enough waste heat from the engine, so they need to rely on air conditioning or other heating systems to provide the heat load required by the vehicle in winter. The high-temperature refrigerant R134a commonly used in most automobiles has poor heating performance under low-temperature conditions, and auxiliary electric heating equipment is required to meet the heating demand, which will increase the energy consumption of the battery. Therefore, the CO 2 The heat pump air-conditioning system with refrigerant is the electric vehicle air-c...

AI Technical Summary

Problems solved by technology

[0002] Electric vehicles have very important application prospects because they are not dependent on fossil fuel resources and are environmentally friendly. However, pure electric vehicles do not have enough waste heat from the engine, so they need to rely on air conditioning or other heating systems to provide the heat load required by the vehicle in winter. The high-temperature refrigerant R134a commonly used in most automobiles has poor heating performance under low-temperature conditions, and auxiliary electric heating equipment is required to meet the heating demand, which will increase the energy consumption of the battery. Therefore, the CO 2 The heat pump air-conditioning system with refrigerant is the electric vehicle air-conditioning that has received widespread attention, CO 2 As an environmentally friendly natural refrigerant, it has excellent heating performance, especially CO2 has good thermal performance at low temperatures

During heating in winter, frosting will occur on the outdoor heat exchanger of the heat pump system, especially when the ambient temperature is around 0°C. Due to the large moisture content and the temperature close to freezing point, the outdoor heat exchanger will be frosted obviously. In the case of insufficient defrosting, icing may even occur. At present, the CO 2 Frosting and defrosting research on outdoor heat exchangers in heat pump systems is still less, especially for micro-channel heat exchangers. The growth of frost layers will seriously deteriorate the heat transfer performance of outdoor heat exchangers, and the heating capacity of heat pump systems cannot meet the needs of winter. vehicle thermal load demand

Images