Spray Cooling Development Effort for Microgravity Environments
01 Feb 2006-Vol. 813, Iss: 1, pp 134-144
TL;DR: In this paper, the fabrication of a spray cooling system aimed at addressing issues pertinent to space applications is presented, such as heat flux capability, orientation, and volumetric packaging, and computer modeling of spray cooling under microgravity conditions as well as comparison to the analogous 1g condition was also performed to gain insight into microgravity behavior.
Abstract: Spray cooling is a high heat flux removal technique considered for systems such as advanced lasers and high power density electronics. Several experiments have been conducted using spray cooling in recent years and various designs of spray cooling devices are continually emerging. At this time, one of NASA’s missions is to enhance future space science capabilities through the application of power lasers and electronics. However, the usage of systems having high heat fluxes can only be achieved with the corresponding development of high power thermal control systems. For the reliable performance of these high‐heat‐flux systems, proper thermal management is imperative. The study presented reviews the fabrication of a spray cooling system aimed at addressing issues pertinent to space applications. These issues include heat flux capability, orientation, and volumetric packaging. Computer modeling of spray cooling under microgravity conditions as well as comparison to the analogous 1‐g condition was also performed to gain insight into microgravity behavior.
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TL;DR: In this article, a review of spray cooling is presented, focusing on the relatively high-flux, low-temperature mechanisms and predictive tools associated with the single-phase liquid cooling and nucleate boiling regimes, as well as critical heat flux (CHF).
346 citations
Cites background from "Spray Cooling Development Effort fo..."
...This numerical approach was later extended to microgravity conditions [130]....
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TL;DR: A discussion of the current status of spray cooling technology as well as NASA's goals, current direction, and challenges associated with the implementation and practice of this technology in the micro-gravity environment is provided in this article.
138 citations
TL;DR: In this article, a spray nozzle array is described that allows for scalable, high-performance cooling, but fluid management remains a challenging concern that may limit the application of this technology.
Abstract: For many years, spray cooling has been known as a promising technology for the removal of high heat fluxes. However, that promise has yet to be fully realized. This work presents a current understanding of the mechanisms of spray cooling and its limitations. To address these limitations, a novel spray nozzle array is described that allows for scalable, high-performance cooling. However, fluid management remains a challenging concern that may limit the application of this technology.
91 citations
01 Jan 2004
TL;DR: In this article, the effects of enhanced surfaces on heat transfer during spray cooling were evaluated on a 2x2 nozzle array with PF-5060 as the working fluid, and the results showed that the straight fins had the largest enhancement in heat flow.
Abstract: Experiments were conducted to study the effects of enhanced surfaces on heat transfer during spray cooling. The surface enhancements consisted of cubic pin fins, pyramids, and straight fins (uniform cross sectional straight fins) machined on the top surface of copper heater blocks. Each had a cross-sectional area of 2.0 square cm. Measurements were also obtained on a heater block with a flat surface for baseline comparison purposes. A 2x2 nozzle array was used with PF-5060 as the working fluid. Thermal performance data was obtained under nominally degassed (chamber pressure of 41.4 kPa ) and gassy conditions (chamber with N2 gas at 101 kPa). The results show that the straight fins had the largest enhancement in heat flow. Critical heat flux (CHF) for this surface showed an increase of 55% in comparison to the flat surface for the nominally degassed condition. The cubic pin finned and pyramid surfaces provided slightly more than half the heat flux enhancement (30% - 40% greater than the flat surface) of the straight fins. The gassy case showed that the straight fins again provided the largest enhancement (48%) in CHF relative to the flat surface. This was followed by the cubic pin fins, and pyramids which had increases of 31% and 18% respectively. No significant effect was observed in the surface temperature at which CHF occurs for either portion of the study.
41 citations
01 Feb 2007
TL;DR: In this paper, the authors explore thermal management solutions for space-based systems and the effects of varying gravity on heat transfer using the level set method to identify the interface of vapor and liquid as explained in Selvam, Lin, and Ponnappan (2005, 2006).
Abstract: Spray cooling is a novel solution for high heat flux applications, whose need is becoming apparent with the advance of high power density electronic systems (lasers, radars, etc). The aim of this investigation is to explore thermal management solutions for space‐based systems and the effects of varying gravity on heat transfer. Previous modeling done by Selvam, Lin, and Ponnappan (2006) used a liquid film thickness of ≈ 40 μm on the heater wall. The two‐phase flow modeling is done using the level set method to identify the interface of vapor and liquid as explained in Selvam, Lin, and Ponnappan (2005; 2006). Modifications to the incompressible Navier‐Stokes equations for surface tension, viscosity, gravity and phase change are discussed in detail. The equations are solved using finite difference method. The computed heat flux in thick layers is compared with previous thin layer heat flux. The computed liquid and vapor interface and temperature distributions are also visualized for better understanding of ...
9 citations
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31 Oct 2002TL;DR: A student or researcher working in mathematics, computer graphics, science, or engineering interested in any dynamic moving front, which might change its topology or develop singularities, will find this book interesting and useful.
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TL;DR: In this article, a level set method for capturing the interface between two fluids is combined with a variable density projection method to allow for computation of two-phase flow where the interface can merge/break and the flow can have a high Reynolds number.
Abstract: A level set method for capturing the interface between two fluids is combined with a variable density projection method to allow for computation of two-phase flow where the interface can merge/break and the flow can have a high Reynolds number. A distance function formulation of the level set method enables one to compute flows with large density ratios (1000/1) and flows that are surface tension driven; with no emotional involvement. Recent work has improved the accuracy of the distance function formulation and the accuracy of the advection scheme. We compute flows involving air bubbles and water drops, to name a few. We validate our code against experiments and theory.
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TL;DR: In this paper, the Hamilton-Jacobi equations and associated theory are used to formulate the interface propagation problem and then algorithms for the initial and boundary value formulations are proposed for semi-conductor manufacturing.
Abstract: Introduction 1 Formulations of interface propagation Part I Theory and Algorithms: 2 Theory of curve and surface evolution 3 Hamilton-Jacobi equations and associated theory 4 Numerical approximations: first attempt 5 Numerical schemes for hyperbolic conservation laws 6 Algorithms for the initial and boundary value formulations 7 Efficient schemes: adaptivity 8 Triangulated versions of level set and fast marching method: extensions and variations 9 Tests of basic methods Part II Applications: 10 Geometry 11 Grid generation 12 Image denoising 13 Computer vision: shape detection and recognition 14 Fluid mechanics and materials sciences: adding physics 15 Computational geometry and computer-aided-design 16 First arrivals, optimizations, and control 17 Applications to semi-conductor manufacturing 18 Comments, conclusions, future directions References Index
3,247 citations