Scroll Compressor Refrigerant Injection Without Oil Dilution
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Solution Overview
Problem
In air-conditioning devices, the injection of liquid refrigerant into the compressor leads to dilution of refrigerating machine oil, causing viscosity decrease and efficiency loss, as well as refrigerant leakage due to oil dilution, and the refrigerant can flow into the oil reservoir, further decreasing viscosity and efficiency.
Innovation Solution
An air-conditioning device configuration with a refrigerant circuit and injection circuit that injects a part of the refrigerant between the first and second expansion valves into specific spaces within the compressor, where it evaporates due to heat generated by the electric motion unit, minimizing oil dilution and refrigerant leakage by maintaining higher viscosity of the refrigerating machine oil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If liquid refrigerant is injected into the compressor to lower discharge temperature, then the discharge temperature decreases, but the refrigerating machine oil is diluted causing viscosity decrease and compressor efficiency decrease
Solution Approach 1:
The injection system is divided into two separate injection paths: a first injection pipe that injects refrigerant into the first space portion (between scroll mechanism and electric motion unit) and a second injection pipe that injects refrigerant into the second space portion (in circulation path). This segmentation allows different injection strategies for different purposes - one for cooling and one for efficiency maintenance
Solution Approach 2:
Different quality refrigerant injection is applied to different locations: the first injection pipe delivers refrigerant to the first space portion where it evaporates using heat from the electric motion unit, while the second injection pipe delivers refrigerant to the second space portion in the circulation path, creating localized quality improvements in different areas
2Temperature
If liquid refrigerant is injected into the suction portion to lower discharge temperature, then the discharge temperature decreases, but the refrigerant flows into the oil reservoir causing refrigerating machine oil viscosity decrease
Solution Approach 1:
The harmful effect of refrigerant mixing with oil is extracted and eliminated by designing separate injection paths that prevent refrigerant from reaching the oil reservoir. The first injection pipe targets the first space portion away from the oil reservoir, and the second injection pipe targets the circulation path, thereby taking out the problematic interaction between refrigerant and oil
Solution Approach 2:
The first space portion and second space portion act as intermediary zones where refrigerant can be injected and evaporated without directly contacting the oil reservoir. These intermediary spaces mediate between the injection point and the oil, preventing direct harmful interaction
3Temperature
If more refrigerant is injected to lower discharge temperature, then the discharge temperature decreases further, but the refrigerant leakage increases due to oil dilution
Solution Approach 1:
The injection system is segmented into two separate paths with different functions, allowing independent control of refrigerant injection for cooling purposes versus maintaining oil quality, thereby enabling refrigerant injection without proportional increase in leakage
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 suppresses the decrease in compressor efficiency and viscosity of the refrigerating machine oil, reducing refrigerant leakage and allowing for increased refrigerant injection, which lowers discharge temperature and improves the coefficient of performance (COP) without requiring increased compressor rotation speed.
Implementation Method 1
evaporated by heat generated by an electric motion unit
Implementation Method 2
the distributed refrigerant is injected from the first injection pipe to a first space portion of a compressor and evaporated by heat generated by an electric motion unit
Implementation Method 3
evaporated by heat generated by an electric motion unit, to thereby cool the refrigerant flowing from a four-way valve into the first space portion
Data Source
AI summary
A compressor of an air-conditioning device includes a scroll mechanism unit having a fixed scroll and an orbiting scroll that cooperates with the fixed scroll to compress refrigerant. There is a first space portion provided between the scroll mechanism unit and an electric motion unit; an annular second space portion provided in a circumference of the scroll mechanism unit in a radial direction; a communication path provided between the first space portion and the second space portion, to guide, to the second space portion, the refrigerant sucked from the suction pipe to the first space portion. A part of the refrigerant between the first expansion valve and the second expansion valve is injected simultaneously to the first space portion and the second space portion.