Capillary Heat Pipe Non-Return Float for Start-Up Reliability
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Solution Overview
Problem
Capillary-pumped heat transport devices face reliability issues during start-up, particularly under high thermal loads, due to the risk of capillary wick drying out and start-up failure.
Innovation Solution
A heat transfer device with a non-return member, comprising a float with a density lower than the fluid's liquid phase, positioned between the evaporator's microporous mass and the reservoir, prevents liquid reflux and allows gas bubbles to pass, ensuring reliable capillary pumping and preventing gas plug formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a non-return valve is used to prevent liquid reflux, then reliability is improved, but device complexity increases
Solution Approach 1:
The float-operated non-return member is automatically actuated by the pressure differential between the evaporator and reservoir, requiring no external control system. The float rises with pressure to open the passage and falls when pressure equalizes to close it, providing self-regulating liquid reflux prevention.
Solution Approach 2:
The invention changes the operational parameter from continuous valve closure to intermittent pressure-driven opening. The non-return member remains closed under normal operation and only opens when evaporator pressure exceeds reservoir pressure, simplifying the mechanism while maintaining reliability.
2Reliability
If a non-return valve is used to prevent liquid reflux, then capillary wick integrity is improved, but ease of operation deteriorates
Solution Approach 1:
The float-operated non-return member is automatically actuated by the pressure differential between the evaporator and reservoir, requiring no external control system. The float rises with pressure to open the passage and falls when pressure equalizes to close it, providing self-regulating liquid reflux prevention.
3Reliability
If a dense non-return member is used, then liquid reflux prevention is improved, but capillary pumping is hindered
Solution Approach 1:
The invention changes the operational parameter from continuous valve closure to intermittent pressure-driven opening. The non-return member remains closed under normal operation and only opens when evaporator pressure exceeds reservoir pressure, simplifying the mechanism while maintaining reliability.
Solution Approach 2:
The float provides a buoyant force that counteracts the weight of the non-return member, enabling it to open easily when pressure differential arises. The float's upward buoyancy force offsets the gravitational force on the non-return member, allowing smooth operation without excessive force requirements.
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 enhances the reliability of start-up and operation by preventing liquid reflux, maintaining the integrity of the capillary wick and allowing for efficient heat transfer, even under high thermal loads.
Implementation Method 1
a float returned by buoyancy thrust towards a range at the closed state
Implementation Method 2
a microporous mass adapted to provide capillary pumping of fluid in the liquid phase
Implementation Method 3
The float has a density lower than the density of the fluid in the liquid phase, and preferably comprised between 60% and 90% of the density of the fluid in the liquid phase; whereby the non-return member does not thwart the capillary pumping. Thus, the resultant of the weight and the Archimedes thrust gives a thrust force P directed upwards.
Data Source
Figure 1~2
Figure 3~4b
Figure 5~6
AI summary
Heat transfer device using capiliary pumping, designed to extract heat from a hot source (11) and surrender this heat to a cold source (12) using a two-phase working fluid, comprising an evaporator (1) having a microporous mass (10) performing capillary pumping of the fluid in the liquid phase, a condenser (2), a reservoir (3) having an interior volume (30) and an inlet and/or outlet orifice (31; 31a, 31b), a vapour communication circuit (4) connecting the outlet of the evaporator to the inlet of the condenser, a liquid communication circuit (5), characterized in that it comprises a nonreturn member (6) positioned between the interior volume (30) of the reservoir and the microporous mass (10) of the evaporator, and designed to prevent liquid present in the evaporator from moving to the interior volume of the reservoir.