Coolant-Assisted Refrigerant Preheating for Extreme Cold Starts
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Solution Overview
Problem
Compressors in refrigerant systems of vehicles fail to operate effectively in extreme cold temperatures due to refrigerant temperature undershoot, limiting the heating system's performance.
Innovation Solution
A system and method that utilizes a coolant loop to transfer heat to the refrigerant loop, using a controller to manage the flow of coolant and refrigerant, and incorporating waste heat sources to prevent refrigerant temperature undershoot by pre-heating the refrigerant before compressor startup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the compressor is started directly in extreme cold temperatures, then the system can quickly provide heating, but the refrigerant temperature undershoot causes the compressor to operate below its minimum operating temperature
Solution Approach 1:
The system performs preliminary heating of the refrigerant using the coolant loop before compressor startup. The controller activates the coolant circulation pump and directs coolant flow through the evaporator to preheat the refrigerant, ensuring the refrigerant temperature is above the minimum operating threshold before the compressor starts, thus preventing temperature undershoot and enabling reliable compressor operation in extreme cold
2Reliability
If the refrigerant is preheated using the coolant loop before compressor startup, then the compressor can operate reliably in extreme cold, but the system complexity increases
Solution Approach 1:
The system uses the existing coolant loop, which serves dual purposes: cooling the propulsion system/battery during normal operation and heating the refrigerant during cold weather startup. The same coolant circulation pump and heat exchanger components are utilized for both cooling and heating functions, eliminating the need for dedicated heating components and reducing overall system complexity
Solution Approach 2:
The system leverages waste heat from the coolant (which may be warm from recent vehicle operation or ambient conditions) to preheat the refrigerant without requiring additional energy input. The controller automatically manages the coolant flow direction and temperature based on sensor feedback, enabling the system to self-regulate the preheating process without complex external control mechanisms
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
Effectively minimizes refrigerant temperature undershoot, enabling the compressor to start and operate efficiently even in extreme cold conditions, thereby enhancing the heating system's performance.
Implementation Method 1
The coolant in a coolant loop, such as a chiller loop, transfers heat to the refrigerant loop to minimize temperature undershoot
Implementation Method 2
heating the refrigerant in the refrigerant loop at the first heat exchanger from the heated coolant
Implementation Method 3
communicating refrigerant through a second portion of the first heat exchanger, heating the refrigerant in the refrigerant loop at the first heat exchanger from the heated coolant
Data Source
AI summary
A method and system are provided and include determining a sensed condition. When the sensed condition is below a first threshold and above a second threshold, the second threshold being less than the first threshold, a flow of coolant is started in a coolant loop comprising a first portion of a first heat exchanger. A flow of refrigerant is started in a refrigerant loop by starting a compressor within the refrigerant loop at a first speed.