Air-conditioning device
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Solution Overview
Problem
Air-conditioning apparatuses using R32 as a refrigerant face excessive compressor discharge temperatures during heating operations, leading to refrigerant and oil deterioration, and existing systems fail to effectively manage temperature control for mixed cooling and heating operations.
Innovation Solution
The air-conditioning apparatus incorporates a refrigerant circuit with a low-pressure shell compressor, a refrigerant flow switching device, and expansion devices to control refrigerant flow, using an injection pipe to manage the refrigerant's discharge temperature, ensuring it remains within safe limits regardless of operation mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If R32 is used as a refrigerant during heating operation, then cooling and heating performance is improved, but discharge temperature becomes excessively high causing refrigerant and oil deterioration
Solution Approach 1:
An injection pipe is introduced as an intermediary component that allows high-pressure liquid refrigerant to be injected into the compression chamber. This intermediary mechanism enables temperature control by introducing cooler refrigerant into the compression process, thereby reducing the discharge temperature while maintaining heating performance.
Solution Approach 2:
The system changes the physical parameters of the refrigerant by injecting high-pressure liquid refrigerant into the compression chamber. This parameter change (from gas to liquid phase, and from low-pressure to high-pressure state) allows control over the discharge temperature while preserving the cooling and heating performance of R32.
2Loss of energy
If expansion device is installed in relay unit or indoor unit, then conveyance power is reduced, but discharge temperature control during heating operation becomes difficult
Solution Approach 1:
The system segments the refrigerant circulation into two independent paths: one path through the expansion device in the relay unit or indoor unit for conveyance power reduction, and another path through the injection pipe for discharge temperature control. This segmentation allows both objectives to be achieved simultaneously without interference.
Solution Approach 2:
The injection pipe system provides multi-functionality by enabling discharge temperature control during heating operations while the expansion device continues to reduce conveyance power. The system universally addresses both energy efficiency and temperature control requirements through complementary mechanisms.
3Object-affected harmful factors
If liquid refrigerant is injected into compressor, then discharge temperature is reduced, but system complexity increases with additional injection components
Solution Approach 1:
The injection pipe system merges with the existing high-pressure liquid pipe infrastructure, utilizing the same refrigerant source and pressure system already present in the air-conditioning apparatus. This merging approach minimizes additional complexity by integrating the temperature control function into the existing system architecture rather than adding completely separate components.
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 effectively prevents refrigerant and oil deterioration by maintaining a safe discharge temperature, enabling reliable operation across various modes, including cooling and heating mixed operations.
Implementation Method 1
a circuit for injecting a liquid from a high-pressure liquid pipe in a refrigeration cycle into the compressor is provided in an air-conditioning apparatus
Implementation Method 2
an expansion device, such as an electronic expansion valve, which decompresses a refrigerant
Implementation Method 3
the first heat exchanger serves as a condenser due to a high-pressure refrigerant being flowed into the first heat exchanger
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A heat pump hot-water supply apparatus 100 controls a second expansion device (expansion device 14a) during a heating operation so as to adjust the amount of refrigerant flowing through an injection pipe 4c, and controls a third expansion device (expansion device 14b) during a cooling operation so as to adjust the amount of refrigerant flowing through the injection pipe 4c.