Multi-Condenser Variable Conductance Heat Pipe for Passive Waste Heat Control
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Solution Overview
Problem
Conventional thermal management systems in aircraft face challenges with low-grade waste heat rejection, significant weight penalties, maintenance issues due to moving parts, and inefficient heat transfer, exacerbated by the electrification of aircraft.
Innovation Solution
A lightweight, passive, and controllable heat pipe system with a variable conductance heat pipe (VCHP) that includes multiple condensers with non-condensable gas reservoirs, allowing active thermal control without moving parts, to manage high-grade waste heat distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If actively pumping a single-phase fluid is used to transport waste heat, then heat can be delivered to end users, but significant weight penalties occur due to pumps and large piping
Solution Approach 1:
The patent replaces the mechanical pumping system with a passive two-phase heat pipe system that uses phase change (evaporation and condensation) of a working fluid to transport heat. The heat pipe contains an evaporator section connected to the heat source and multiple condenser sections that can be selectively activated, eliminating the need for mechanical pumps and large piping infrastructure.
Solution Approach 2:
The invention utilizes phase transitions of the working fluid within the heat pipe - the fluid evaporates at the evaporator section absorbing heat from the source, the vapor travels to condenser sections where it condenses releasing heat to end users, and the liquid returns to the evaporator. This phase change mechanism enables efficient heat transport without mechanical assistance.
2Productivity
If actively pumping a single-phase fluid is used, then heat can be transported throughout the aircraft, but maintenance issues arise due to moving parts
Solution Approach 1:
The patent eliminates all moving parts by replacing the active pumping system with a passive heat pipe system that relies on natural phase change processes. The heat pipe contains no pumps, valves, or mechanical components, making it inherently more reliable and maintenance-free while still achieving effective heat transport throughout the aircraft.
Solution Approach 2:
The heat pipe system is self-regulating through the phase change mechanism - the working fluid automatically evaporates at the hot end and condenses at the cold end without external control, and the liquid return is driven by capillary forces or gravity, eliminating the need for mechanical intervention or maintenance.
3Productivity
If a single-phase fluid is pumped, then heat can be delivered to end users, but power requirements reduce net propulsive efficiency
Solution Approach 1:
The patent replaces the energy-intensive mechanical pumping system with a passive heat pipe system that requires no external power input. The phase change process and natural convection currents within the heat pipe enable heat transport without consuming electrical power, thereby preserving net propulsive efficiency of the aircraft.
4Productivity
If conventional thermal management systems are used, then waste heat can be transported, but relatively low heat transfer coefficients result in large temperature drops
Solution Approach 1:
The invention exploits the high latent heat of vaporization and condensation of the working fluid to achieve efficient heat transfer. The phase change process occurs at constant temperature, enabling large amounts of heat to be transferred with minimal temperature difference, thereby eliminating the large temperature drops associated with conventional single-phase fluid systems.
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 system efficiently delivers and rejects thermal energy to various end users, reducing weight penalties and maintenance needs, while maintaining consistent evaporator temperatures despite varying power and heat sink conditions.
Implementation Method 1
a heat pipe connected to the heat source and configured to transfer thermal energy from the heat source to a plurality of condensers
Implementation Method 2
a variable conductance heat pipe containing a working fluid vapor
Implementation Method 3
Each of the plurality of condensers includes a reservoir containing a non-condensable gas, and at least one of the plurality of condensers is controlled by at least one of: heating or cooling the respective reservoir of the non-condensable gas, changing a volume of the respective reservoir, or changing an amount of non-condensable gas in the respective reservoir
Data Source
AI summary
In some implementations, a thermal management system includes a heat source and a heat pipe connected to the heat source and configured to transfer thermal energy from the heat source to a plurality of condensers, each of the plurality of condensers branching off from a main pipe of the heat pipe. The heat pipe can be a variable conductance heat pipe containing a working fluid vapor. Each condenser contains a reservoir of non-condensable gas (NCG). At least one of the condensers can be controlled by heating/cooling the respective reservoir of NCG, by reservoir volume changing via bellows, and/or by NCG amount changing via NCG insertion/extraction.