Refrigerant Injection Circuit for Stable Low-Temperature Heating
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Solution Overview
Problem
Conventional refrigeration/air conditioning equipment experiences unstable operation due to fluctuations in liquid refrigerant level caused by gas injection, leading to reduced heating capacity and inefficient defrosting, especially at low outdoor temperatures.
Innovation Solution
The equipment incorporates a four-way valve, compressor, indoor and outdoor heat exchangers, an intermediate-pressure receiver, and a second internal heat exchanger for gasification of bypassed refrigerant, which is injected into the compressor, stabilizing the fluid volume and enhancing heating capacity while preventing discharge temperature reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If gas injection is performed to increase heating capacity, then heating capacity is improved, but liquid refrigerant level in the gas-liquid separator fluctuates causing unstable operation
Solution Approach 1:
A gas-liquid separator is introduced as an intermediary device between the condenser and evaporator to separate gas and liquid refrigerants. This mediator prevents liquid refrigerant from being injected into the compressor while ensuring stable gas refrigerant supply for heating capacity enhancement.
Solution Approach 2:
The system changes the physical state parameters of the refrigerant by separating gas and liquid phases in the gas-liquid separator. This parameter change ensures that only gas refrigerant is injected into the compressor, maintaining stable operation while achieving enhanced heating capacity.
2Power
If injection flow rate is increased to enhance heating capacity, then heating capacity improves, but liquid refrigerant is injected into the compressor causing operation instability
Solution Approach 1:
The gas-liquid separator acts as a protective intermediary that filters out liquid refrigerant before injection. This ensures that even when injection flow rate is increased for enhanced heating capacity, only gas refrigerant enters the compressor, preventing operation instability.
3Ease of operation
If conventional heater is used for defrosting operation, then defrosting is achieved, but heating capacity is not significantly increased during heating operation
Solution Approach 1:
The gas injection system serves multiple functions: it enhances heating capacity during normal heating operation and provides defrosting capability when needed. This multi-functional approach eliminates the need for a separate conventional heater, maintaining heating capacity while enabling efficient defrosting.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration provides stable operation with increased heating capacity and improved defrosting efficiency, even at low outdoor temperatures, by maintaining sufficient heat-exchange performance and preventing discharge temperature reduction.
Implementation Method 1
a second internal heat exchanger that exchanges heat between a refrigerant having a pressure reduced by the second decompressor and the refrigerant between the indoor heat exchanger and the first decompressor
Implementation Method 2
a first internal heat exchanger that exchanges heat between a refrigerant in the intermediate-pressure receiver and a refrigerant in a suction pipe of the compressor
Data Source
AI summary
Refrigeration/air conditioning equipment includes a first internal heat exchanger for exchanging heat between a refrigerant to be sucked in a compressor and a high-pressure liquid refrigerant, an injection circuit for evaporating a bypassed high-pressure liquid at intermediate pressure and injecting the vaporized refrigerant into the compressor, a second internal heat exchanger for exchanging heat between the high-pressure liquid refrigerant and the refrigerant to be injected, and a heat source for heating the refrigerant to be injected.