An Experimental Study of Spray Cooling of High Temperature Surfaces PDF Download

Author: Raymond Emil Gaugler
Publisher:
ISBN:
Category :
Languages : en
Pages : 83

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Author: Alex M. Tulchinsky
Publisher:
ISBN:
Category : Electronic apparatus and appliances
Languages : en
Pages : 306

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Book Description
Spray impingement cooling has been shown to be a leading candidate for future high heat flux cooling applications. In general, spray cooling curves consist of three heat flux regimes; single-phase, two-phase and critical heat flux (CHF). CHF is considered the design limit for almost all two-phase cooling applications, as a rapid increase in temperature and decrease in heat flux occurs beyond this point. Recent studies have shown that the addition of micro-structures on the impingement surface can enhance heat transfer relative to a smooth surface. In the present study, spray cooling curves are obtained for two micro-structured surfaces and are compared to smooth surface results. Micro-structured surfaces consisted of bio-inspired fractal-like geometries, denoted as grooves and fins, extending in a radial direction from the center to the periphery of a 37.8 mm circular disc. Depending on the location on the surface, dimensions of groove widths and heights varied from 100 to 500 um, and 30 to 60 um, respectively. Fin width and height dimension remained constant throughout the surface at 127 and 60 um, respectively. Heat flux and wall temperature at the impingement surface were calculated from temperature data measured at multiple locations below the impingement surface. Results are presented as heat flux, q" , versus the wall-to-spray temperature difference, deltaT[subscript w], at each of 5 volume flux, Q", conditions ranging from 0.54 to 2.04 x 10−3 m3/m2s. Convection coefficients, h[subscript cv], and spray efficiencies, n, are also presented for each case as a function of q" and deltaT[subscript w] , respectively. Results of the study indicate that at low and high volume fluxes, an improvement in heat transfer occurs in the single-phase regime for the fin geometry. Enhancement in the single-phase regime did not occur at the intermediate volume flux condition of 1.37 x 10−3 m3/m2s. At all volume flux states tested, significant enhancements, as high as 50% in some cases, were observed in the two-phase regime for the fin structure, whereas the groove structure performed identically to the flat surface in the single-phase regime and exhibited a large degradation in the two-phase and critical heat flux regimes (~50%). Critical heat flux for the fin surface compared to the flat surface was slightly lower at low volume flux conditions, equivalent at the intermediate volume flux, and slightly greater at high volume flux conditions. Further investigations into the underlying mechanisms responsible for these results are needed.

Author: James B. Fillius
Publisher:
ISBN: 9781423521440
Category : Cooling
Languages : en
Pages : 79

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Spray cooling is a promising means of dissipating large steady state heat fluxes in high density power and electronic systems, such as thermophotovoltaic systems. The present study reports on the effectiveness of spray cooling in removing heat fluxes as high as 220 W/cm2. An experiment was designed to determine how the parameters of spray volumetric flow rate and droplet size influence the heat removal capacity of such a system. A series of commercially available nozzles were used to generate full cone water spray patterns encompassing a range of volumetric flow rates (3.79 to 42.32 L/h) and droplet Sauter mean diameters (17.4 to 35.5 micrometers). The non-flooded regime of spray cooling was studied, in which liquid spreading on the heater surface following droplet impact is the key phenomenon that determines the heat transfer rate. The experimental data established a direct proportionality of the heat flux with spray flow rate, and an inverse dependence on the droplet diameter. A correlation of the data was developed to predict heat flux as a function of the studied parameters over the range of values tested in this experiment.

Author: Hamed Muhammed A. Al-Ahamdi
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Author: John W. Schaefer
Publisher:
ISBN:
Category : Heat flux
Languages : en
Pages : 52

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Author: Abdul-Rahman Bleik
Publisher:
ISBN:
Category :
Languages : en
Pages : 154

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Author: Andrea C. Ashwood
Publisher:
ISBN:
Category :
Languages : en
Pages : 144

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Author: Tony Tung-Ming Man
Publisher:
ISBN:
Category : Integrated circuits
Languages : en
Pages : 194

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Book Description

Author: Rainer F. Ponzel
Publisher:
ISBN:
Category : Cooling
Languages : en
Pages : 212

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Book Description

Author: Matthew A. Cryer
Publisher:
ISBN: 9781423547877
Category :
Languages : en
Pages : 61

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Book Description
Recent studies have shown that thermophotovoltaic (TPV) technology is a promising source of high power density generation. Enhanced TPV systems can theoretically provide power densities of up to 100 W/cm2. The inherent ineffiencies in the system dictate that up to 90% of that energy is not converted to electrical power, and must be removed as waste heat to ensure that the components are maintained at a reasonable operating temperature. The present study addresses this issue by investigating the suitability of using spray cooling techniques to remove heat generated by power densities of up to 100 W/ cm2. A simple, scaleable experiment was designed using low cost commercially available components to study the effects that spray mass flux and droplet size have on the heat removal capacity of the system. A series of nozzles were used so that mass flux and droplet size could be studied independently, giving high resolution to the data so that predictive correlations could be developed over the range of parameters varied in the study.