Accumulator Heater Sensing for Refrigerant Liquid Flow-Back Prevention
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Solution Overview
Problem
Existing refrigerating cycle systems face complications and increased costs due to the use of liquid level detectors in accumulators, which can lead to reduced reliability and poor maintenance properties, as they are prone to failure and require labor-intensive refrigerant removal for maintenance.
Innovation Solution
Incorporating an electric heating element at the maximum liquid level in the accumulator, which monitors power consumption changes to detect the presence of liquid refrigerant and initiates protective measures to prevent liquid flow-back, such as reducing compressor speed or shutting it down, without the need for a separate sensor, thus simplifying the system and improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a liquid level detector is provided in the pressure vessel of the accumulator, then liquid flow-back can be prevented, but the structure becomes complicated and manufacturing cost increases
Solution Approach 1:
The heating element performs dual functions: heating the refrigerant to prevent liquid flow-back and serving as a liquid level detector. When the liquid level rises to contact the heating element, the element's temperature and electrical resistance change, providing liquid level detection capability without requiring a separate detector.
Solution Approach 2:
The heating element used for liquid level detection is simpler and more replaceable than traditional liquid level detectors. When it wears out or fails, it can be easily replaced without complex disassembly, improving maintenance efficiency and reducing costs.
2Reliability
If a liquid level detector is used, then liquid flow-back can be prevented, but manufacturing cost increases
Solution Approach 1:
The heating element performs dual functions: heating the refrigerant to prevent liquid flow-back and serving as a liquid level detector. When the liquid level rises to contact the heating element, the element's temperature and electrical resistance change, providing liquid level detection capability without requiring a separate detector.
Solution Approach 2:
The liquid level detection function is merged with the heating function by using the heating element itself as the detection sensor, eliminating the need for separate detection components and reducing overall system cost.
3Reliability
If a liquid level detector is installed, then liquid flow-back can be prevented, but maintenance property deteriorates due to refrigerant removal requirement
Solution Approach 1:
The heating element used for liquid level detection is simpler and more replaceable than traditional liquid level detectors. When it wears out or fails, it can be easily replaced without complex disassembly, improving maintenance efficiency and reducing costs.
Solution Approach 2:
The heating element is designed as a separate, modular component that can be independently replaced. The detection function is segmented from complex sensor systems and integrated into the replaceable heating element, simplifying maintenance procedures.
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 liquid flow-back while maintaining system efficiency and reducing maintenance burdens, as the electric heating element can be used for both liquid level detection and temperature sensing, and can be easily replaced without draining the refrigerant.
Implementation Method 1
detects change of a heating value of the electric heating element by change of power consumption
Implementation Method 2
the temperature of a heating apparatus provided in a bottom of the accumulator is raised, so that a liquefied refrigerant is heated to a temperature not lower than a saturation temperature to be vaporized
Data Source
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AI summary
Liquid flow-back is prevented, and a compressor (4) is protected by a simple and low-cost configuration having high reliability and an excellent maintenance property. In a heating and cooling air conditioning system of the present invention, a gas-liquid mixed refrigerant sucked into an electric compressor (4) is separated, and only a vaporized refrigerant is sucked by an electric compressor (4), an electric heating element (23, 23A) is provided at a position of an allowable highest liquid level (H3) of a liquefied refrigerant (R) in an accumulator (12) storing a predetermined amount of the liquefied refrigerant (R), and a controller detects change of a heating value of the electric heating element (23) as change of power consumption, and performs protection operation for lowering the liquid level of the liquefied refrigerant (R) in a case where the power consumption reaches a predetermined threshold value.