PCM Accumulator Valve Control for Phase-Change HVAC Efficiency
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Solution Overview
Problem
Existing HVAC systems using phase change materials (PCMs) for heating and cooling face challenges in efficiency, controllability, and practical implementation, particularly in effectively managing the phase changes of PCMs to enhance thermal energy transfer.
Innovation Solution
The system comprises a first heat exchanger, a force unit, a PCM accumulator, a valve system, and a control unit. The control unit manages the valve system to disconnect the PCM accumulator during compression and connect it during expansion, allowing for efficient phase change management and thermal energy transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the PCM accumulator is continuously connected to the heat exchanger, then the system structure is simpler, but the controllability and efficiency during compression and expansion cycles deteriorate
Solution Approach 1:
The valve system dynamically changes the connectivity state between the PCM accumulator and heat exchanger based on the operational phase (compression or expansion). During compression, the valve disconnects the accumulator to allow efficient compression of PCM in the heat exchanger. During expansion, the valve connects the accumulator to enable PCM expansion. This dynamic reconfiguration improves controllability without significantly increasing overall system complexity.
2Loss of energy
If mechanical compression is applied to enhance phase change and thermal energy transfer, then the coefficient of performance (COP) improves, but the system complexity and control requirements increase
Solution Approach 1:
A valve system acts as an intermediary component to control the connectivity between the PCM accumulator and heat exchanger during compression and expansion cycles. This intermediary enables the mechanical compression process to be efficiently controlled, improving the coefficient of performance by ensuring proper timing and isolation of components during phase change operations.
3Productivity
If the valve system disconnects the PCM accumulator during compression, then the efficiency of thermal energy transfer improves, but the control system complexity increases
Solution Approach 1:
The valve system operates periodically, switching between connected and disconnected states in synchronization with the compression and expansion cycles. During compression phases, the valve disconnects the PCM accumulator to maximize thermal energy transfer efficiency. During expansion phases, the valve reconnects the accumulator. This periodic action pattern improves productivity while keeping the control system manageable through rhythmic, predictable operation.
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 improves the coefficient of performance (COP) and controllability of the system, enhancing the efficiency of thermal energy transfer and providing a more practical implementation of PCM-based HVAC systems.
Implementation Method 1
The compression of the PCM causes a phase change, during which thermal energy can be transferred between the PCM and another medium
Implementation Method 2
a force unit configured to be fluidly connected to the first outer end of the first heat exchanger and configured to compress the phase change material in the first heat exchanger
Implementation Method 3
the first heat exchanger is configured to receive a phase change material... during compression of the phase change material... thermal energy can be transferred between the PCM and another medium
Data Source
AI summary
System for cooling and/or heating at least one medium, comprising: a first heat exchanger comprising a first outer end and a second outer end, wherein the second outer end is closed, wherein the first heat exchanger is configured to receive a phase change material; a force unit configured to be fluidly connected to the first outer end of the first heat exchanger and configured to compress the phase change material in the first heat exchanger; a PCM accumulator configured to receive phase change material; and a control unit configured to: during compression of the phase change material in the first heat exchanger by the force unit, fluidly disconnect the PCM accumulator from the first heat exchanger; and during expansion of the phase change material in the first heat exchanger, fluidly connect the PCM accumulator with the first heat exchanger for allowing phase change material to expand into the PCM accumulator.