Generic mathematical formulation of the total heat transfer coefficients between heated radiant floor surfaces and rooms

2021 ◽  
pp. 108701
Author(s):  
Meijie Wang ◽  
Panpan Li ◽  
Weijie Liu
Keyword(s):  
Heat Transfer ◽  
Mathematical Formulation ◽  
Total Heat ◽  
Transfer Coefficients ◽  
Total Heat Transfer ◽  
Heat Transfer Coefficients ◽  
Floor Surfaces

Analysis of a Triple-Effect Low Temperature Distillation Desalination Process

2011 ◽  
Vol 204-210 ◽  
pp. 2001-2006
Author(s):  
Li Xi Zhang ◽  
Li Xi Zhang ◽  
He Fei Zhang
Keyword(s):  
Heat Transfer ◽  
Low Temperature ◽  
Total Heat ◽  
Utilization Rate ◽  
Transfer Coefficients ◽  
Total Heat Transfer ◽  
Heat Transfer Coefficients ◽  
New Process ◽  
Heat Loads ◽  
Source Flow

A new process of low temperature triple-effect distillation desalination is designed. Firstly, the appropriate effect number is determined. The total heat transfer coefficients and the heat loads of each evaporator are calculated. When the pressure differences between near effects are equal to △P, the freshwater outputs and the heat transfer coefficients of every effect would be increased as △P improved; if △P is too low, the seawater un-evaporated in the last evaporator would be difficult to flow into the next one. By analysis, the appropriate value of △P is 0.005 MPa. If the seawater flowing into the first effect is preheated by the heat source flow outpouring the unit, the total heat utilization rate and the freshwater output would be enhanced.

scholarly journals Heat Transfer Coefficients for Staggered Arrays of Short Pin Fins

1981 ◽  
Author(s):  
G. J. VanFossen
Keyword(s):  
Heat Transfer ◽  
Reynolds Numbers ◽  
Transfer Coefficients ◽  
Total Heat Transfer ◽  
Optimum Length ◽  
Trailing Edge ◽  
Heat Transfer Coefficients ◽  
Casting Technology ◽  
Nusselt Numbers ◽  
Pin Fins

Short pin fins are often used to increase the heat transfer to the coolant in the trailing edge of a turbine blade. Due primarily to limits of casting technology, it is not possible to manufacture pins of optimum length for heat transfer purposes in the trailing edge region. In many cases the pins are so short that they actually decrease the total heat transfer surface area compared to a plain wall. A heat transfer data base for these short pins is not available in the literature. Heat transfer coefficients on pin and endwall surfaces were measured for several staggered arrays of short pin fins. The measured Nusselt numbers when plotted versus Reynolds numbers were found to fall on a single curve for all surfaces tested. The heat transfer coefficients for the short pin fins (length to diameter ratios of 1/2 and 2) were found to be about a factor of two lower than data from the literature for longer pin arrays (length to diameter ratios of about 8).

Performance of Aluminum and Carbon Foams for Air Side Heat Transfer Augmentation

2010 ◽  
Vol 132 (12) ◽  
Author(s):  
Patrick T. Garrity ◽  
James F. Klausner ◽  
Renwei Mei
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Aluminum Foam ◽  
Carbon Foam ◽  
Ambient Air ◽  
Total Heat ◽  
Coefficient Of Performance ◽  
Transfer Model ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients

The air side heat transfer performance of three aluminum foam samples and three modified carbon foam samples are examined for comparison with multilouvered fins often found in compact heat exchangers. The aluminum foam samples have a bulk density of 216 kg/m3 with pore sizes of 0.5, 1, and 2 mm. The modified carbon foam samples have bulk densities of 284, 317, and 400 kg/m3 and machined flow passages of 3.2 mm in diameter. The samples were placed in a forced convection arrangement using a foil heater as the heat source and ambient air as the sink. A constant heat flux of 9.77 kW/m2 is applied throughout the experiments with the mean air velocity ranging from 1 to 6 m/s as the control parameter. The steady volume-averaged momentum equation and a two-equation nonequilibrium heat transfer model are employed to extract the volumetric heat transfer coefficients. Pressure drop measurements are correlated with the Darcy–Forcheimer relation. Empirical heat transfer correlations for the aluminum and carbon foam samples are provided. Using a hypothetical heat exchanger considering only the thermal resistance between the ambient air and the outer tube wall, the air side performance for each sample is modeled based on the local heat transfer coefficients and friction factors obtained from experiments. The performance of each sample is evaluated based on a coefficient of performance (COP, defined as the ratio of the total heat removed to the electrical input of the blower), compactness factor (CF, defined as the total heat removed per unit volume), and power density (PD, defined as the total heat removed per unit mass). Results show the carbon foam samples provide significant improvement in CF but the COP and PD are considerably lower than that for comparable multilouvered fin heat exchangers.

Heat-Transfer Coefficients for Staggered Arrays of Short Pin Fins

1982 ◽  
Vol 104 (2) ◽  
pp. 268-274 ◽  
Author(s):  
G. J. VanFossen
Keyword(s):  
Heat Transfer ◽  
Reynolds Numbers ◽  
Transfer Coefficients ◽  
Total Heat Transfer ◽  
Optimum Length ◽  
Trailing Edge ◽  
Heat Transfer Coefficients ◽  
Casting Technology ◽  
Nusselt Numbers ◽  
Pin Fins

Short pin fins are often used to increase the heat transfer to the coolant in the trailing edge of a turbine blade. Due primarily to limits of casting technology, it is not possible to manufacture pins of optimum length for heat-transfer purposes in the trailing edge region. In many cases the pins are so short that they actually decrease the total heat-transfer surface area compared to a plain wall. A heat-transfer data base for these short pins is not available in the literature. Heat-transfer coefficients on pin and endwall surfaces were measured for several staggered arrays of short pin fins. The measured Nusselt numbers when plotted versus Reynolds numbers were found to fall on a single curve for all surfaces tested. The heat-transfer coefficients for the short pin fins (length to diameter ratios of 1/2 and 2) were found to be about a factor of two lower than data from the literature for longer pin arrays (length to diameter ratios of about 8).

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