Phase Change Actuated Valve for Passive Heat Pipe Flow Control
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Solution Overview
Problem
Existing heat pipe systems in wrap-around heat exchangers require expensive and bulky electrically controlled valves that consume power and are not suitable for refrigerant service, lacking a hermetically sealed, compact, and passively thermally actuated solution to control fluid flow effectively.
Innovation Solution
A thermally actuated heat pipe control valve using a phase change material actuator that blocks fluid flow at a predetermined temperature, utilizing a sealed chamber with phase change material to move a passage closing member and prevent heat transfer between the condenser and evaporator portions, allowing for a fully passive operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrically controlled valves (solenoid valves and actuated ball valves) are used to control heat pipe flow, then the valve can be hermetically sealed and provide an open low pressure drop flow path, but the valve requires electrical or pneumatic power input, thermal feedback sensors, and is relatively expensive
Solution Approach 1:
The valve uses the heat pipe's own thermal energy to actuate the valve mechanism. The phase change material absorbs heat from the heat pipe when temperature exceeds the phase change point, automatically closing the valve without external power input. This self-service approach eliminates the need for electrical power, sensors, and external control systems while maintaining hermetic sealing.
Solution Approach 2:
The invention employs a phase change material that transitions from solid to liquid at a predetermined temperature. This phase transition drives the valve closing mechanism, providing a passive thermal actuation system that responds automatically to temperature conditions without requiring external electrical control.
2Ease of operation
If electrically controlled valves are used in heat pipes, then flow control is achieved, but the valve is bulky and requires complex electrical control systems
Solution Approach 1:
The valve system performs flow control using only the thermal energy present in the heat pipe. The phase change material automatically responds to temperature conditions, eliminating the need for electrical controllers, power supplies, and complex control circuitry. This reduces device complexity while maintaining effective flow control capability.
Solution Approach 2:
The invention extracts the control function from external electrical systems and embeds it within the heat pipe itself using a passive phase change material actuator. This removes the bulky external control systems and integrates the control mechanism directly into the heat pipe structure.
3Use of energy by moving object
If known phase change material valves are used, then passive thermal actuation is achieved, but the valve does not have an open low pressure drop flow path and is not designed for refrigerant heat pipe service
Solution Approach 1:
The valve is designed with a dynamic flow path that transitions from fully open to fully closed based on temperature conditions. The passage closing member moves dynamically in response to phase change material expansion, providing an open low pressure drop flow path during normal operation and complete closure when needed, optimizing both heat transfer efficiency and passive actuation.
Solution Approach 2:
The invention changes the physical state of the phase change material from solid to liquid at a predetermined temperature, which drives the passage closing member to block the flow path. This parameter change approach enables passive thermal actuation while maintaining an open flow path during normal operation, ensuring high heat transfer efficiency.
4Reliability
If valves are added to heat pipes to control working fluid flow, then heat pipe operation and efficiency are improved, but the valve must be hermetically sealed and compact
Solution Approach 1:
The valve components are nested within a compact housing that integrates with the heat pipe structure. The phase change material actuator, passage closing member, and sealing elements are arranged in a nested configuration that minimizes overall valve volume while maintaining hermetic sealing and effective flow control for heat pipe 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
The solution provides a cost-effective, compact, and reliable valve that reduces power consumption with increasing temperature, enabling efficient modulation of heat pipe flow and preventing overheating without the need for electrical inputs, thus enhancing dehumidification capacity and reducing system complexity.
Implementation Method 1
As the temperature of the phase change material reaches a designed temperature, the phase change material melts and expands causing the passage closing member to move into the passage to a closed position
Implementation Method 2
the phase change material melts and expands causing the passage closing member to move
Implementation Method 3
preventing heat transfer between the condenser portion and the evaporator portion when the designed temperature is reached or exceeded
Data Source
AI summary
A thermally actuated heat pipe control valve including a housing, a phase change material actuator, and a passage closing member. A passage extends through the housing and is configured to receive working fluid from the heat pipe therein. The phase change material actuator is positioned in the housing and has a sealed chamber with phase change material positioned therein. The passage closing member is positioned in the housing proximate to or in the passage and proximate to the phase change material actuator. The passage closing member has a surface which cooperates with a wall of the passage. As the temperature of the phase change material reaches a designed temperature, the phase change material melts and expands causing the passage closing member to move into the passage to a closed position, preventing heat transfer between the condenser portion and the evaporator portion when the designed temperature is reached or exceeded.