scholarly journals Experimental Heat Transfer Study on Green Roofs in a Semiarid Climate during Summer

2015 ◽  
Vol 2015 ◽  
pp. 1-15 ◽  
Author(s):  
Roy J. Issa ◽  
Kenneth Leitch ◽  
Byungik Chang
Keyword(s):  
Heat Transfer ◽  
Soil Moisture ◽  
Clay Soil ◽  
Green Roofs ◽  
Climatic Conditions ◽  
Conductive Heat ◽  
Transfer Rates ◽  
Experimental Heat ◽  
Pulse Sensor ◽  
Experimental Heat Transfer

An experimental study was conducted on green roofs under the semiarid summer climatic conditions of West Texas to investigate the effect of soil type, moisture content, and the presence of a top soil grass layer on the conductive heat transfer through the roof. Two soil types were investigated: uniform sand and local silt clay. Tests were also conducted on a control roof. A dual-needle heat-pulse sensor was used to conduct thermal property tests on the soils. The tests reveal that unlike sand, the thermal conductivity of silt clay did not increase continuously with soil moisture. Better heat transfer conditions were achieved when the sand and silt clay roofs were watered to a water depth of 10 mm per day rather than double the amount of 20 mm per day. The roof with silt clay soil had the lowest fluctuation in inner temperature between daytime and nighttime. Green roofs with silt clay soil required more than twice the amount of soil moisture than green roofs with sand to achieve similar roof heat transfer rates. The best net heat flux gains for vegetated green roofs were 4.7 W/m2 for the sand roof and 7.8 W/m2 for the silt clay roof.

Heat Transfer With Film Cooling Near Nontangential Injection Slots

1968 ◽  
Vol 90 (2) ◽  
pp. 157-162 ◽  
Author(s):  
D. E. Metzger ◽  
H. J. Carper ◽  
L. R. Swank
Keyword(s):  
Heat Transfer ◽  
Injection Site ◽  
Film Cooling ◽  
Surface Heat ◽  
Test Facility ◽  
Fluid Injection ◽  
Transfer Rates ◽  
Experimental Heat ◽  
Experimental Heat Transfer ◽  
Secondary Fluid

A study of the effect of secondary fluid injection through single nontangential slots on the surface heat transfer in regions near the injection site is presented. The nondimensional parameters governing the heat transfer are obtained from the pertinent differential equations, and experimental results were obtained which cover the range of interest of these parameters for many situations encountered in film cooling applications. The experimental heat transfer rates were obtained from a novel transient test facility, and are presented as ratios of the heat transfer obtained with film injection to the heat transfer obtained with only the single mainstream.

An Experimental Study of Forced-Convection Heat Transfer From a Sphere to Liquid Sodium

1968 ◽  
Vol 90 (1) ◽  
pp. 9-12 ◽  
Author(s):  
L. C. Witte
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Convection Heat Transfer ◽  
Reynolds Numbers ◽  
Liquid Sodium ◽  
Convection Heat ◽  
Transfer Rates ◽  
Experimental Heat ◽  
Experimental Heat Transfer ◽  
Heated Metal

Experimental heat-transfer rates from spheres moving through liquid sodium have been obtained. The experimental data were obtained by a transient technique in which a heated metal sphere was passed through a pool of liquid sodium. Heat-transfer rates up to 3.58 × 106 Btu/(hr)(ft2) were calculated from the experimental measurements. Reynolds numbers, based on the sphere velocity and diameter, ranged from 35,000 to 153,000. The experimental data were correlated by an expression similar to theoretical expressions obtained from potential-flow theory.

Stagnation-Point Heat-Transfer Rate in Nitrogen Plasma Flows: Theory and Experiment

1970 ◽  
Vol 92 (3) ◽  
pp. 372-384 ◽  
Author(s):  
Arthur F. Okuno ◽  
Chul Park
Keyword(s):  
Heat Transfer ◽  
Stagnation Point ◽  
Nitrogen Plasma ◽  
Molecular Dissociation ◽  
Transfer Rates ◽  
High Enthalpy ◽  
Experimental Heat ◽  
Experimental Heat Transfer ◽  
The Mean ◽  
Theory And Experiment

A theory for the heat transfer to the stagnation point of a hemisphere in a supersonic, high-enthalpy, low-density nitrogen plasma flow was developed. The theory assumed a flow that is frozen with respect to molecular dissociation and relaxing with respect to ionization. The calculations for this partially frozen flow yielded heat-transfer rates that were generally lower than predicted by other theories for both frozen and equilibrium flows. Experimental heat-transfer rates from measurements in a high-enthalpy constricted-arc tunnel agreed with the theoretical value within 10 percent in the mean.

Heat Transfer Between a Moving Surface and a Flowing Medium

1976 ◽  
Vol 98 (4) ◽  
pp. 659-661 ◽  
Author(s):  
T. R. Bott ◽  
D. V. Law
Keyword(s):  
Heat Transfer ◽  
High Surface ◽  
High Water ◽  
Surface Heat ◽  
Moving Surface ◽  
Transfer Rates ◽  
Experimental Heat ◽  
Experimental Heat Transfer ◽  
Back Mixing ◽  
The Heat Transfer Coefficient

Certain processes involve heat transfer across a moving surface and application of the well-known “penetration theory” to scraped-surface heat transfer, suggests that this theory might be applied to this situation. At high water flows and high surface speeds experimental results agree well with the theory, but at lower values the experimental heat-transfer rates are much higher than those predicted from the theory, and at high surface speeds and lower water velocities the experimental value of the heat transfer coefficient is lower than predicted. The differences are attributed to additional turbulence and secondary-flow (back-mixing) effects, which would be extremely difficult to allow for in the theory.

scholarly journals Experimental heat transfer evaluation in a porous media

2021 ◽  
Vol 1868 (1) ◽  
pp. 012016
Author(s):  
S Pedrazzi ◽  
G Allesina ◽  
M Puglia ◽  
N Morselli ◽  
F Ottani ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Experimental Heat ◽  
Experimental Heat Transfer
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