Compressor Refrigerant Injection for Low-Temperature Heating Capacity
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Solution Overview
Problem
Air-conditioning systems face issues with refrigerant temperature increase and compressor damage when operating at low outside air temperatures, leading to insufficient heating capacity and user discomfort, as the refrigerant density decreases, causing high compression ratios and excessive temperature rises.
Innovation Solution
The air-conditioning apparatus incorporates a refrigerant flow switching device, heat exchangers, and an injection pipe system that injects refrigerant at an intermediate pressure during compression, merging refrigerant streams to reduce discharge temperature and maintain heating capacity, while using sensors and controllers to manage flow rates and pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the outside air temperature is below -10 degrees C, then the refrigerant evaporating temperature decreases, but the refrigerant density decreases and heating capacity becomes insufficient
Solution Approach 1:
The patent changes the physical parameters of the refrigerant by injecting a two-phase refrigerant into the compression process. This injection modifies the density and temperature characteristics of the refrigerant being compressed, allowing the system to maintain adequate refrigerant density even when the evaporating temperature is low due to cold outside air conditions
2Stress or pressure
If the refrigerant density decreases at low outside air temperature, then the compression ratio increases, but the discharge temperature becomes excessively high causing compressor damage
Solution Approach 1:
The patent introduces a two-phase refrigerant as an intermediary substance injected into the compression process. This injected refrigerant acts as a mediator that absorbs excess heat during compression, thereby controlling the discharge temperature while allowing the compression ratio to increase as needed for low evaporating temperature conditions
3Productivity
If a two-phase refrigerant is injected into the compressor at intermediate pressure, then the refrigerant flow rate increases, but the discharge temperature suppression effect is reduced when outside air temperature is very low
Solution Approach 1:
The patent implements dynamic control of the refrigerant injection system, adjusting the injection amount and timing based on operating conditions. The controller dynamically modifies injection parameters to optimize the balance between maintaining adequate refrigerant flow rate and suppressing discharge temperature under varying low temperature outdoor conditions
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 refrigerant temperature increases, prevents compressor damage, and ensures a sufficient heating capacity even at low outside air temperatures, enhancing user comfort by stabilizing the system's performance.
Implementation Method 1
inject a two-phase refrigerant into a region where an intermediate pressure is obtained in the compression process of the compressor
Implementation Method 2
compression process of the compressor
Implementation Method 3
heat is transferred from the high-pressure gas refrigerant to the indoor air so that the refrigerant liquefies into a two-phase refrigerant
Implementation Method 4
the refrigerant liquefies into a two-phase refrigerant
Implementation Method 5
compression process of the compressor
Data Source
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AI summary
In the case of a heating operation in which a use side heat exchanger functions as a condenser when the outside air has a predetermined low temperature, a low-outside-air-temperature heating operation start mode is executed in which, while a refrigerant, as discharged from a compressor, flows into the use side heat exchanger, the refrigerant, upon flowing into the injection pipe, merges with a part of the refrigerant discharged from the compressor, which has traveled through the connecting pipe and has transferred heat in the heat source side heat exchanger, and a merged refrigerant is supplied to the injection port of the compressor, and thereafter a low-outside-air-temperature heating operation mode is executed in which the refrigerant, as discharged from the compressor, is supplied to the injection port of the compressor via the injection pipe while flowing into the use side heat exchanger.