PCM Heat Exchanger with Elastomeric Expansion Compensation
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Solution Overview
Problem
Conventional vehicle heat exchangers using a mixture of antifreeze and water as coolant face issues with reduced latent heat of fusion and potential damage due to water expansion when freezing, leading to cracking of the heat exchanger housing.
Innovation Solution
A three-fluid phase change material (PCM) heat exchanger is designed with an intake air channel, a PCM layer comprising water that expands when freezing and elastomeric devices to compress and prevent damage, and a refrigerant channel for cooling the PCM layer to a solid state using a vapor-compression cycle refrigeration system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If water is used as PCM fluid to maximize latent heat of fusion, then cooling efficiency is improved, but the heat exchanger housing may crack due to water expansion during freezing
Solution Approach 1:
The patent incorporates an elastomeric device within the PCM layer that compresses when water freezes and expands, providing beforehand cushioning to absorb the expansion pressure and prevent cracking of the heat exchanger housing. This allows the system to use pure water as PCM fluid while protecting against the harmful expansion effect.
2Reliability
If antifreeze is added to water to prevent freezing, then heat exchanger damage is prevented, but the latent heat of fusion is reduced
Solution Approach 1:
The patent extracts the antifreeze from the PCM fluid composition, using pure water as the PCM fluid instead of an antifreeze-water mixture. The freezing protection function is transferred to the elastomeric device that physically accommodates expansion, thereby preserving the high latent heat of fusion property of pure water.
3Strength
If the PCM layer is made rigid to maintain structural integrity, then housing damage is prevented, but the PCM fluid expansion during freezing causes cracking
Solution Approach 1:
The patent introduces an elastomeric device within the PCM layer that provides flexible, compliant accommodation for the PCM fluid expansion during freezing. This flexible element absorbs the expansion pressure without transmitting it to the housing, preventing cracking while maintaining housing structural integrity.
4Productivity
If the heat exchanger is designed for maximum cooling capacity, then intake air cooling efficiency is improved, but the system complexity increases with additional components
Solution Approach 1:
The patent merges the expansion accommodation function with the existing PCM layer structure by incorporating the elastomeric device directly within the PCM layer. This integration approach allows the system to achieve maximum cooling capacity with pure water PCM while adding minimal complexity, as the elastomeric device is embedded within rather than added as a separate external component.
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
The solution allows for efficient cooling of intake air, increasing its density and enabling higher engine performance while preventing heat exchanger damage, and can be effectively charged for high-performance applications like drag racing.
Implementation Method 1
a PCM layer surrounding the intake air channel and configured to cool the intake air, the PCM layer comprising a second set of fins, a PCM fluid that expands when freezing
Implementation Method 2
The addition of antifreeze to water, however, also lowers its latent heat of fusion, i.e., the amount of energy needed to change the mixture from solid (frozen) to liquid
Implementation Method 3
a refrigerant channel surrounding the PCM layer and configured to circulate a refrigerant to cool the PCM layer to a solid, frozen state
Implementation Method 4
A heat exchanger is a device used to transfer heat between two or more fluids
Implementation Method 5
a PCM fluid that expands when freezing, and a set of elastomeric devices configured to compress to compensate for the PCM fluid expansion during freezing
Data Source
AI summary
A three fluid phase change material (PCM) heat exchanger for a vehicle comprises (i) an intake air channel having a first set of fins disposed therein and configured to receive and output intake air prior to combustion by an engine of the vehicle, (ii) a PCM layer surrounding the intake air channel and configured to cool the intake air, the PCM layer comprising a second set of fins, a PCM fluid that expands when freezing, and a set of elastomeric devices are configured to compress to compensate for the PCM fluid expansion during freezing, and (iii) a refrigerant channel surrounding the PCM layer and configured to circulate a refrigerant to cool the PCM layer to a solid, frozen state.