Devices, systems, and methods for the rapid transient cooling of pulsed heat sources
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Solution Overview
Problem
Conventional cooling techniques struggle to maintain stable temperatures in high-power devices with transient heat loads, as they assume steady-state conditions and fail to effectively manage rapid thermal changes, leading to inefficiencies and potential device failure.
Innovation Solution
A heat transfer device utilizing flash boiling, which involves depressurizing a fluid to induce a rapid phase-change process, allowing for efficient convective heat transfer and temperature regulation by leveraging the latent heat of vaporization to cool high-heat-flux devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional cooling techniques (pool boiling, jet impingement, spray, microchannel) are used, then steady-state cooling is achieved, but transient thermal fluctuations cannot be eliminated and start-up periods are prolonged
Solution Approach 1:
The patent utilizes flash boiling, a rapid phase transition process, where a liquid coolant undergoes sudden vaporization upon contact with the heated surface. This phase change absorbs large amounts of latent heat rapidly, enabling the cooling system to respond immediately to transient heat loads without prolonged start-up periods, thereby achieving both temperature stability and rapid response
Solution Approach 2:
The cooling system employs periodic pulsing of the coolant flow synchronized with the pulsed heat load. By delivering coolant in controlled pulses rather than continuous flow, the system achieves optimal cooling during each pulse while minimizing thermal fluctuations between pulses, effectively managing transient thermal conditions
2Speed
If cooling is activated in a stepwise manner with conventional techniques, then some transient response is achieved, but thermal resistance and capacitance result in unavoidable thermal fluctuations
Solution Approach 1:
Flash boiling provides an inherently transient cooling mechanism where the rapid phase transition occurs throughout the coolant bulk rather than just at the boundary layer. This volumetric phase change delivers intense cooling exactly when and where the heat pulse occurs, achieving both rapid response and temperature uniformity without the thermal fluctuations inherent in stepwise conventional cooling
Solution Approach 2:
The flash boiling process is self-regulating and inherently synchronized with the heat load. The rapid vaporization automatically adjusts to the magnitude and timing of heat pulses without requiring external control mechanisms, providing both fast response and stable temperature control through the natural physics of the phase transition process
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 enables rapid and effective cooling of high-heat-flux devices by actively controlling the cooling rate to match the heat load, reducing thermal overshoot and maintaining a stable temperature, even during transient events, thus enhancing device performance and extending its operational lifespan.
Implementation Method 1
a heat exchanger in thermal communication with one or more heat sources and the first chamber, the heat exchanger for receiving heat energy from the one or more heat sources and uniformly distributing the heat energy
Implementation Method 2
when fluid is received within the interior of the first chamber and the chamber is depressurized, a flash boiling event can occur within the first chamber
Implementation Method 3
The liquid superheat, which is not easily attainable in traditional boiling hierarchies and is typically characterized by the Jakob number, provides the requisite latent enthalpy for rapid phase change and, as a result, high rates of expansion and cooling
Implementation Method 4
a convective transfer of heat energy from the one or more heat sources into the fluid results
Data Source
AI summary
Heat transfer devices and systems are provided for the rapid cooling of pulsed high-powered, high-flux devices using flash boiling. Such devices comprise at least two fluidly connected chambers and a heat exchanger in thermal communication with a heat source. A flash boiling event is actively triggered at a location close to the heat source by rapid depressurization of the chamber containing a multi-phase coolant. This boiling process allows for high heat transfer rates from the heat source into the chambers due to the latent heat of vaporization, which results in the rapid cooling of the heat source. A porous medium may also be positioned within a chamber of the device to enhance boiling nucleation and extended surface heat transfer. Methods of rapidly cooling pulsed heat sources are also provided using the devices and systems hereof.