EV Refrigerant Management for Compressor Cold Start Protection
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Solution Overview
Problem
In electric vehicle heat flux management systems, refrigerant pooling occurs when idle, leading to insufficient refrigerant volume for compressor operation in cold ambient conditions, risking compressor failure.
Innovation Solution
A refrigerant management system with sensors monitoring temperature and pressure at the compressor inlet, initiating a cold start mode by temporarily reversing refrigerant flow from the condenser to the accumulator when superheated refrigerant or a significant temperature gradient is detected, ensuring adequate refrigerant supply for compressor operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the refrigerant system operates in heating mode with condenser isolated from compressor, then heating function is achieved, but refrigerant may pool away from compressor causing insufficient refrigerant volume for compressor operation
Solution Approach 1:
The system performs preliminary action by detecting superheated refrigerant conditions at compressor inlet before compressor operation begins, and initiates refrigerant redistribution through the condenser in advance to prevent insufficient refrigerant volume during cold start
Solution Approach 2:
The system uses temperature and pressure sensors at the compressor inlet to continuously monitor refrigerant state, providing feedback to the control system which adjusts valve positions to redistribute refrigerant when superheated conditions are detected, ensuring adequate refrigerant volume for reliable compressor operation
2Reliability
If temperature and pressure sensors are added to monitor refrigerant at compressor inlet, then refrigerant management is improved, but device complexity increases
Solution Approach 1:
The system employs self-service by using the existing compressor operation parameters and standard temperature/pressure sensors to automatically detect superheated refrigerant conditions and trigger refrigerant redistribution, eliminating the need for complex external monitoring systems
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
Prevents compressor failure by redistributing refrigerant during cold start conditions, allowing safe transition between heating and cooling modes without risking compressor damage.
Implementation Method 1
the sensor detects one or both of: a superheated refrigerant at the compressor inlet
Implementation Method 2
a temperature gradient of more than 3 Kelvin between ambient and the compressor inlet
Implementation Method 3
a valve between the condenser and the compressor is operable to open to initiate a cold start mode in which a temporary fluid communication is provided between the condenser and the compressor
Data Source
AI summary
A refrigerant management system in a heat flux management system for an electric vehicle and a method of refrigerant management is provided. The system includes a vehicle air conditioning circuit including a heat pump circuit and a refrigeration cycle refrigerant circuit, the air conditioning circuit including a heat pump condenser in thermal communication with a heat source, a refrigerant evaporator in thermal communication with the heat source, an evaporator associated with an expansion valve, and a refrigerant compressor where the components are fluidly connected to one another by a refrigerant line. An accumulator is fluidly coupled in the refrigerant line downstream of the heat pump condenser, the refrigerant evaporator and evaporator and upstream of the refrigerant compressor, and the air conditioning circuit is switchable between a heating mode and a cooling mode in which the refrigerant circuit is in fluid communication with the compressor by actuation of at least one valve.