Low-pressure ratio working condition heat pump system and its control method based on supplementary air enthalpy-increasing cycle

Abstract

The present invention proposes a low-pressure ratio working condition heat pump system and its control method based on the air-supplementing and enthalpy-increasing cycle, which solves the problem that the exhaust temperature of the existing heat pump system under the low-pressure ratio working condition is low, which affects the reliability of the compressor and the refrigerant. Filling problem. The low-pressure ratio working condition heat pump system includes a compressor, a condensing heat exchanger, a first throttling element, a second throttling element, an evaporating heat exchanger, and an economizer; the heat pump system is filled with refrigerant and lubricating oil; the compressor The outlet of the condensing heat exchanger is connected to the inlet of the condensing heat exchanger, and the outlet pipeline of the condensing heat exchanger is divided into two routes, one of which is connected to the inlet of the cold end of the economizer through the first throttling element, and the other is connected to the inlet of the hot end of the economizer ; The outlet of the cold end of the economizer is connected with the air inlet of the compressor to supply air; the outlet of the hot end of the economizer is connected with the inlet of the compressor through the second throttling element and the evaporative heat exchanger in turn; the heat exchange area of ​​the economizer is 1.2‑2 times the heat exchange area of ​​the original economizer.

Description

technical field [0001] The invention belongs to the field of refrigeration, and in particular relates to a low-pressure ratio working condition heat pump system and a control method thereof based on an air-supplementing and enthalpy-increasing cycle. Background technique [0002] Since entering the 21st century, energy conservation and environmental protection have become the development theme of the refrigeration and air-conditioning industry. Among them, the heating heat pump system mainly uses HCFC22, HFC410A, etc. as the working fluid of the system. However, the discharge of this type of refrigerant into the atmosphere will cause the problem of ozone layer destruction. Therefore, HCFC refrigerants have entered the phase-out stage. Under the multi-objective constraints of environmental protection, safety, economy, and energy efficiency conversion capabilities, there are fewer and fewer types of alternative refrigerants. The natural refrigerant propane (R290) has the adv...

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Problems solved by technology

[0008] The purpose of the present invention is to solve the problem that the exhaust temperature of the heat pump system under the existing low-pressure ratio working condition is low, thereby affecting the reliability of the compressor and the refrigerant charging amount, and proposes a low-pressure ratio based on the gas-supplementing and enthalpy-increasing cycle. Working condition heat pump system and its control method, the system utilizes the residual heat brought by the temperature difference between the high temperature of the outlet of the condensing heat exchanger and the saturation temperature of the supplementary air to increase the superheat of the supplementary air, thereby controlling the superheat of the exhaust gas, thereby ensuring that the R290 / lubricating oil mixture viscosity, improve system reliability

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