Solar thermal storage type two-stage compressed air source heat pump system and its operation method

Abstract

The invention relates to the field of heat pumps, and is a solar heat storage type two-stage compressed air source heat pump system, which includes two variable capacity compressors, two outdoor heat exchangers, a flash evaporator, an electronic expansion valve, and a heat storage tank. Its characteristics Yes, the system has cooling and heating operation modes. Under the two operation modes, there are three compression operation modes: single, parallel and two-stage. In the system, two outdoor heat exchangers are configured in parallel, and an inter-stage hot gas bypass circuit is set. Combined with the solar thermal storage device, together with the solenoid valve and the one-way valve, it forms a defrosting cycle for uninterrupted heating. The effects and benefits of the present invention are that the capacity of the compressor can be adjusted during the cooling, heating and defrosting processes of the system, the solar thermal storage device overheats the refrigerant, and the outdoor heat exchangers are arranged in parallel to defrost alternately, realizing the system at low temperature Provides heat to the room in a smooth climate. The system is used in living rooms in cold regions, and has wide application space and energy-saving significance.

Description

technical field [0001] The invention belongs to the field of heat pumps, in particular to a solar heat storage type two-stage compressed air source heat pump system and its operating method. Background technique [0002] When the existing air source heat pump operates in a low temperature environment, there are problems such as a sharp decrease in heating capacity and an excessively high exhaust temperature of the compressor; at the same time, when the ambient temperature is lower than 0°C, a large area will appear on the surface of the outdoor heat exchanger. The frosting phenomenon will lead to the decrease of the heat exchange performance of the outdoor heat exchange equipment, and have a great impact on the comprehensive heating performance of the heat pump device. At present, variable capacity and (quasi) two-stage compression technologies are often used to improve the heating capacity of air source heat pumps in low temperature environments. Among them, the variable c...

AI Technical Summary

Problems solved by technology

For the two-stage heat pump compression system, if reverse defrosting is adopted, the pressure of the high-pressure stage, middle stage and low-pressure stage changes greatly before and after the system defrosting, resulting in a longer period for the system to restore stable operation. The system stability in the frosting process is poor, so reverse defrosting is difficult to apply to two-stage compression systems; for hot gas bypass defrosting, two-stage heat pump compression heat pump systems usually use high-pressure stage compressor exhaust bypass defrosting, this method defrosting The frosting process not only affects the indoor temperature and the thermal comfort of the human body, but also the system heating performance coefficient is low; at the same time, during the defrosting process, it is difficult to adjust the capacity of the system's high and low pressure compressors reasonably

In addition, when the defrosting of the system ends, the refrigerant in the bypass circuit of the defrosting cycle flows directly from the outdoor heat exchanger into the suction port of the low-pressure compressor. As a result, a large amount of liquid refrigerant enters the compressor, causing great damage to the compressor; in addition, solar water heaters have been widely used in households as equipment for providing domestic hot water, but they have a single purpose and have not yet fully utilized their functions

So far, there are no literature reports and practical applications on the solar thermal storage type two-stage compressed air source heat pump system and its operation method

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