Air-conditioning apparatus
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Solution Overview
Problem
Air-conditioning apparatuses using refrigerants like R32 face issues with excessively high discharge temperatures during heating operations, leading to refrigerant and oil deterioration, and existing systems struggle with concurrent cooling and heating operations and refrigerant circulation reversals.
Innovation Solution
An air-conditioning apparatus with a refrigeration cycle that includes a compressor, heat exchangers, expansion devices, and a suction-injection pipe system, allowing for the injection of refrigerant into the compressor's suction side during both cooling and heating modes, with a controller regulating the suction-injection flow rate and refrigerant flow switching to manage discharge temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If R32 refrigerant is used in heating operation, then cooling performance is improved, but discharge temperature becomes excessively high causing refrigerant and oil deterioration
Solution Approach 1:
The patent applies preliminary action by injecting liquid refrigerant into the compressor suction side before compression occurs. This pre-cools the refrigerant and reduces the discharge temperature that would otherwise occur during heating operations with R32 refrigerant, preventing deterioration of the refrigerant and lubricating oil while maintaining cooling performance
2Temperature
If liquid refrigerant is injected into compressor suction side during heating operation, then discharge temperature is reduced, but system complexity increases requiring additional valves and control mechanisms
Solution Approach 1:
The patent implements universality by designing an injection system that can operate in both heating and cooling modes. The same injection pipe, solenoid valve, and expansion valve assembly are used regardless of operation mode, eliminating the need for separate injection systems for each mode and reducing overall system complexity
Solution Approach 2:
The patent uses an existing high-pressure liquid pipe from the refrigeration cycle to serve as the injection pipe. Instead of creating a completely new injection system, it copies and repurposes the existing high-pressure liquid line, thereby reducing the number of additional components needed and simplifying the overall injection system design
3Adaptability or versatility
If check valves are arranged in parallel with expansion devices to enable suction-injection during heating and cooling, then injection capability is achieved, but specialized indoor units are required reducing system adaptability
Solution Approach 1:
The patent extracts the injection function from the indoor unit and relocates it to the outdoor unit. By placing the solenoid valve and injection pipe in the outdoor unit where the high-pressure liquid pipe is already present, the indoor unit remains simple and unchanged, eliminating the need for specialized indoor units with parallel check valves while maintaining injection capability during both heating and cooling operations
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 system effectively reduces compressor discharge temperature, ensuring safe operation and extending the service life of the refrigerant and oil, while enabling concurrent cooling and heating operations without requiring specialized indoor units.
Implementation Method 1
a suction-injection pipe (4c) configured to introduce, into a suction side of the compressor (10), a refrigerant in a liquid or two-phase state
Implementation Method 2
a third expansion device (14a) configured to generate, in a case where the first heat exchanger (12) functions as an evaporator, medium pressure that is lower than high pressure
Implementation Method 3
a first heat exchanger (12), a first expansion device (14a), and second heat exchangers (15a, 15b) that are connected by pipes
Data Source
Figure 1
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AI summary
An air-conditioning apparatus 100 includes a suction-injection pipe 4c that introduces a refrigerant in a liquid or two-phase state into a suction side of a compressor 10, an expansion device 14b that is arranged at the suction-injection pipe 4c, and a controller 50 that regulates the suction-injection flow rate of a refrigerant introduced into the suction side of the compressor 10 through the suction-injection pipe 4c by controlling the opening degree of the expansion device 14b.