A Comparison of Jet and Spray Impingement Cooling PDF Download

Author: Kerry Oliphant
Publisher:
ISBN:
Category : Electronic apparatus and appliances
Languages : en
Pages : 194

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Author: Scott Allen Berning
Publisher:
ISBN:
Category : Disks, Rotating
Languages : en
Pages : 184

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Author: Xin Feng
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages :

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Among the thermal management solutions for power electronics, two-phase jet or spray impingement cooling are two promising candidates. In this study, electrohydrodynamic atomization (EHDA) method is used to generate spray and jet from the same capillary. This approach enables us to compare the heat transfer coefficient and critical heat flux (CHF) in consistent conditions. Two nondimensional parameters are first developed to lay out the various EHDA modes of ethanol. The experimental results show that the EHDA cooling could enhance the heat transfer coefficient in most conditions, while it could not benefit CHF because the electric repulsive force causes a wide spray angle and less impinging mass flux on the surface. Single and multi micro jet impingement cooling (MJIC) are investigated. Based on the experimental observation and analytical works, a semi-theoretical CHF correlation is proposed based on force and energy balance. The experimental data of water and ethanol are predicted very well by the new model. It also shows the potential to explain the unique feature on the CHF curves of saturated HFE7000 and subcooled ethanol. By using multi MJIC, heat transfer coefficient and CHF might be improved, which mainly depend on fluids and testing conditions.

Author: S. M. Sohel Murshed
Publisher: BoD – Books on Demand
ISBN: 1789848385
Category : Science
Languages : en
Pages : 154

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Book Description
Since conventional cooling techniques are increasing falling short of meeting the ever-growing cooling demands of high heat generating devices, thermal systems, and processes, advanced and innovative cooling technologies are of immense importance to deal with such high thermal management. Hence, this book covers a number of key topics related to advanced cooling approaches, their performance, and applications, including: Evaporative air cooling; Spray impingement cooling; Heat pump-based cooling; Modular cooling for photovoltaic plant; Nucleate pool boiling of refrigerants; Transient flashing spray cooling and application; Compressor cooling systems for industry. The book is aimed at a wide variety of people from graduate students and researchers to manufacturers who are involved or interested in the areas of thermal management systems, cooling technologies, and their applications.

Author: Alexander John Zielinski
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Zhaojun Wang
Publisher: Springer Nature
ISBN: 9811395241
Category : Technology & Engineering
Languages : en
Pages : 931

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This book presents selected papers from the 11th International Symposium on Heating, Ventilation and Air Conditioning (ISHVAC 2019), with a focus on HVAC techniques for improving indoor environment quality and the energy efficiency of heating and cooling systems. Presenting inspiration for implementing more efficient and safer HVAC systems, the book is a valuable resource for academic researchers, engineers in industry, and government regulators.

Author: Khaider Abu Bakar
Publisher:
ISBN:
Category : Heat
Languages : en
Pages : 74

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Cooling system using jet impingement is already widely used in industries nowadays. There were various approaches that have been investigated in order to produce more efficient jet impingement cooling system. This thesis is study about the effect of the nozzle angle on jet impingement in order to identify the relationship in heat transfer. Besides, investigation on spacing distance between nozzle's edge to the impingement surface and Reynolds number at certain angle also identified in this study. Those studies are needed parallel to the current researchers endeavor for future development of cooling system in global industries. The experiment were perform by vary 3 major parameters such as angle of the nozzle (30°, 45°, 60°, and 90°), distance between nozzle's edge to the impinge surface (H/d= 2, 4, 6, and 8) and also Reynolds number (Re= 2300, 1960,930 and 500).The heat source are heated at 100 0C and cooled down by the flow of air from the nozzle. The heat source temperature after cooling are measured and collected. The result discovers about the relationship nozzle angle for jet impingement cooling system which is heat transfer are more efficient when the angle of nozzle approaching to the normal line as the Nusselt Number are more higher at 90° in range 31.5 w/m2K of heat transfer coefficient compare to the lower angles of the nozzle. Furthermore, higher Reynolds number and close range of distance between nozzle's edges to impingement surface will also gives high Nusselt number which means both also effective cooling effects for the systems.

Author: Ri Li
Publisher:
ISBN:
Category : Electronic books
Languages : en
Pages : 0

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The cooling of a surface can be achieved by the impingement of spray, which is a free surface flow of droplets ejected from a spray nozzle. Spray cooling can provide uniform cooling and handle high heat fluxes in both single phase and two phases. In this chapter, spray cooling is reviewed from two aspects: the entire spray (spray level) and droplets (droplet level). The discussion on the spray level is focused on the spray cooling performance as a function of fluid properties, flow conditions, surface conditions, and nozzle positioning. The advantages and barriers of using spray cooling for engineering applications are summarized. The discussion on the droplet level is focused on the impact of droplet flow on film flow, which is the key flow mechanism in spray cooling. Droplet flow involves single droplet, droplet train (continuously droplets broke up from jet flow), and droplet burst (droplet groups affecting at a constant frequency), and local cooling enhancement due to droplet flow is discussed in details. Future work and unresolved issues in spray cooling are proposed.

Author: Chris Schaffer
Publisher:
ISBN:
Category :
Languages : en
Pages : 78

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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The objective of this project was to perform a comprehensive numerical study for the prediction of conjugate heat transfer during jet impingement cooling. Calculations were done primarily for two working fluids: MIL-7808 and ammonia. A number of substrate materials were studied. The investigation considered both free and confined jet configurations using circular and slot nozzles. Fifteen different disk or plate thicknesses ranging from 0 to 12 mm and eleven different nozzle heights from 0.4 mm to 12.5 mm were used. A number of heat source patterns were considered to explore the effects of magnitude and location of heat generation. Both steady state heat transfer and the transient start-up of power were investigated. It was found that the magnitude of local heat transfer coefficient or Nusselt number decreased with time at all locations on the disk. A higher heat transfer coefficient at the impingement location was seen at a smaller thickness, whereas a thicker plate provided a more uniform distribution of heat transfer coefficient. Materials with a higher thermal conductivity provided more uniform distribution of interface temperature as well as the heat transfer coefficient. Both local and average heat transfer coefficient increased with Reynolds number. For a given flow rate, a higher heat transfer coefficient was obtained with smaller nozzle diameter. Compared to MIL-7808 and FC-77, ammonia provided smaller solid-fluid interface temperature and higher heat transfer coefficient.