Compressor Injection Control for R32 Air-Conditioning Heat Management
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Solution Overview
Problem
Air-conditioning systems using R32 refrigerant face issues with high compressor discharge temperatures, leading to refrigerant and oil degradation, especially during heating operations at low outside air temperatures, and lack effective methods for simultaneous cooling and heating operations.
Innovation Solution
An air-conditioning apparatus with a refrigeration cycle that includes a compressor with a low-pressure shell structure, a first heat exchanger, a first expansion device, and one or more second heat exchangers, connected by refrigerant pipes and an injection pipe, using a refrigerant mixture of R32 and HFO1234yf or R32 and HFO1234ze, with a controller controlling the injection quantity into the compressor to manage discharge temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If R32 refrigerant is used in air-conditioning systems, then cooling efficiency is improved, but compressor discharge temperature becomes too high causing refrigerant and oil degradation
Solution Approach 1:
The patent changes the chemical composition parameter of the refrigerant from pure R32 to a mixture containing HFO-1234yf or HFO-1234ze, which fundamentally alters the thermal properties and discharge temperature characteristics while maintaining cooling efficiency
Solution Approach 2:
The patent creates a composite refrigerant system by combining R32 with HFO-1234yf or HFO-1234ze in specific ratios, leveraging the complementary properties of each component to achieve both high efficiency and low discharge temperature
2Adaptability or versatility
If heating operation is performed at low outside air temperature, then heating capability is maintained, but discharge temperature rises excessively causing degradation
Solution Approach 1:
The patent modifies the refrigerant's thermal parameters through chemical composition changes, enabling the system to maintain heating capability at low ambient temperatures while keeping discharge temperature within safe operational limits
3Temperature
If injection method from high-pressure liquid pipe is used, then discharge temperature is reduced, but cooling and heating mixed operation is not supported
Solution Approach 1:
The patent designs a refrigerant composition that inherently provides low discharge temperature across all operational modes including cooling, heating, and mixed operations, eliminating the need for mode-specific injection control
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
The solution effectively controls discharge temperature, preventing refrigerant and oil degradation and enabling safe operation, while supporting both cooling and heating modes efficiently.
Implementation Method 1
injects refrigerant from an injection pipe into a compression chamber, thereby lowering a discharge temperature of the compressor
Implementation Method 2
a compressor that compresses a low pressure refrigerant and discharges a high pressure refrigerant
Implementation Method 3
a first heat exchanger that exchanges heat between a refrigerant and an external fluid, and one or more second heat exchangers that exchange heat between the refrigerant and the external fluid
Data Source
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AI summary
Provided is an air-conditioning apparatus able to reliably apply control such that the discharge temperature does not become too high with a refrigerant such as R32 whose compressor discharge temperature readily rises, and thus suppress degradation of the refrigerant and the refrigerating machine oil. An injection pipe 4c that injects a heat source side refrigerant into a compressor 10 is installed, connected a pipe between a backflow prevention device 20 and an opening and closing device 24 installed on a branching pipe 4d, and an aperture unit in the compressor 10.