Loop Heat Pipe Evaporator Priming for Supercritical Startup
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional Loop Heat Pipes (LHPs) face challenges in starting up when the working fluid is in a supercritical state, requiring liquid presence in the reservoir before operation and needing subcooled liquid return, which limits their operation at sub-ambient temperatures.
Innovation Solution
The heat transport system includes a priming system that converts fluid into a liquid to prime the evaporator, using a secondary evaporator and reservoir to manage vapor and liquid flow, allowing operation from a supercritical state by applying heat to the secondary evaporator and using a cold-biased reservoir to facilitate liquid formation and circulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional LHPs require liquid presence in the reservoir before operation, then the system can start up reliably, but the operational temperature range is limited and subcooled liquid return is needed
Solution Approach 1:
The patent changes the physical state parameter of the working fluid from requiring liquid phase to allowing supercritical state operation. The reservoir is designed to hold supercritical fluid instead of liquid, and the system operates by transitioning between supercritical and two-phase states during the heat transfer cycle, eliminating the need for subcooled liquid return and expanding operational temperature range
Solution Approach 2:
The system pre-charges the reservoir with supercritical working fluid before operation begins. This preliminary charging with supercritical fluid (rather than liquid) enables the system to start up directly in supercritical mode without requiring pre-cooled liquid, thus resolving the contradiction between startup reliability and temperature range adaptability
2Reliability
If LHPs use subcooled liquid return to maintain operation, then thermal balance can be maintained, but operation at sub-ambient temperatures is limited
Solution Approach 1:
The patent changes the thermal state parameter from requiring subcooled liquid to using supercritical fluid. The reservoir maintains supercritical fluid at temperatures above the critical point, and heat transfer occurs through phase transitions from supercritical to two-phase states, eliminating the requirement for subcooled liquid return and enabling operation at sub-ambient temperatures
Solution Approach 2:
The system utilizes phase transitions between supercritical and two-phase states as the primary heat transfer mechanism. The supercritical fluid absorbs heat, transitions to a two-phase state in the heat transfer channel, and returns to supercritical state after heat rejection, maintaining thermal balance without requiring subcooled liquid return
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
Enables the LHP to start up and operate effectively from a supercritical state, managing parasitic heat and heat conduction issues, and maintaining thermal balance, thus expanding its operational temperature range beyond conventional limitations.
Implementation Method 1
These systems utilize capillary pressure developed in a fine-pored wick within the evaporator to promote circulation of working fluid from the evaporator to the condenser and back to the evaporator
Implementation Method 2
The heated wall is in intimate contact with the primary wick. Heat acquired by the evaporator is transported to and discharged by the condenser
Implementation Method 3
The evaporator includes a primary wick and a core that includes a fluid flow passage. Heat acquired by the evaporator is transported to and discharged by the condenser
Implementation Method 4
a condenser thermally coupled to the heat sink, fluid that flows between the evaporator and the condenser
Data Source
AI summary
A heat transfer system includes an evaporator having a heated wall, a liquid barrier wall containing working fluid, a primary wick positioned between the heated wall and an inner side of the liquid barrier wall, a vapor removal channel located at an interface between the primary wick and the heated wall, and a liquid flow channel located between the liquid barrier wall and the primary wick. Methods of transferring heat include applying heat energy to a vapor barrier wall, flowing liquid through a liquid flow channel, pumping the liquid from the liquid flow channel through a primary wick, and evaporating at least some of the liquid at a vapor removal channel.