Cross-critical CO2 parallel compression system and capacity ratio method thereof

Abstract

The invention discloses a cross-critical CO2 parallel compression system and a capacity ratio method thereof. The system comprises a main loop and an auxiliary loop, and the temperature of the outletof a main loop of a gas cooler is reduced to the temperature of the outlet of a main loop of a supercooling-evaporator through the evaporation effect of the auxiliary loop in the supercooling-evaporator. The system comprises three working modes, the environment temperature is minus 20 DEG C to zero DEG C in a normal operation mode, and the frequency of the auxiliary loop compressor is adjusted toensure the efficient operation of the system; the environment temperature is 0-15 DEG C in a low-frequency operation mode, when the environment temperature is high and the heating amount is large, theenergy is saved by reducing the frequency; the environment temperature is lower than minus 20 DEG C in an ultra-frequency operation mode, so that the heating amount and the running stability of the system under an extremely low environment temperature are guaranteed; and the water return temperature in the three modes ranges from 35 DEG C to 50 DEG C, and the water outlet temperature ranges from50 DEG C to 70 DEG C. In the starting process, a low-frequency starting mode of the auxiliary loop compressor is carried out when the pressure of the auxiliary loop is less than 5 MPa, and the stability of the starting operation process of the auxiliary loop is ensured.

Description

technical field [0001] The invention belongs to the technical field of heat pumps and relates to a transcritical CO 2 Parallel compression system and its capacity ratio method. Background technique [0002] A heat pump is a technology that transfers heat energy from a low level to a high level through a thermal cycle by consuming energy to do work such as mechanical energy, electrical energy, and thermal energy. Most of the traditional heat pumps used in heating systems use traditional working fluids such as R134a and R410a, which are poor in environmental protection and are facing phase-out. Instead, a heat pump system for heating using natural working fluid, CO 2 With its high thermal conductivity and constant pressure specific heat, smaller gas density, viscosity and surface tension, it is more suitable as a refrigerant. CO 2 As a refrigerant, it has good environmental protection performance. It is an inert gas and has no toxicity; its chemical structure is stable, it...

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Problems solved by technology

[0007] The object of the present invention is to provide a transcritical CO 2 Parallel compression system and its capacity ratio method to ensure the existing transcritical CO 2 The performance of the parallel compression system can reach the optimal state at each ambient temperature, solving the frequency ratio problem of the main circuit and auxiliary circuit compressors under different ambient temperatures

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