Transient Convective Heat Transfer During and After Gas Injection Into Containers

1975 ◽  
Vol 97 (2) ◽  
pp. 282-287 ◽  
Author(s):  
J. D. Means ◽  
R. D. Ulrich
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Gas Injection ◽  
High Heat ◽  
Transfer Rates ◽  
High Heat Transfer ◽  
Short Period ◽  
Bottom Injection

This paper presents experimental data correlations for the spatially averaged convective heat transfer coefficient for thin-walled closed containers during and after gas injection. The different modes of heat transfer are identified, and correlations are presented for each. Correlations are presented for the injection period, post-top injection, post-bottom injection, post-tangential injection, post-radial injection, and post-ejection heat transfer for various tank geometries. Of special significance are the very high heat transfer rates that are shown to be present in some cases immediately after injection. Heat transfer rates are shown to be, for a short period, up to almost two orders of magnitude higher than natural convection predictions would indicate.

Gas Turbimes for High-Specific-Output Industrial Heat-Transfer Equipment

1972 ◽  
Vol 186 (1) ◽  
pp. 205-220
Author(s):  
E. Kellett
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Gas Turbine ◽  
Convective Heat ◽  
Gas Turbines ◽  
Low Cost ◽  
Heat Transfer Fluid ◽  
Transfer Rates ◽  
High Heat Transfer ◽  
Pressurized Combustion

The incompatibility of the dual role of air as a combustion and heat-transfer fluid is apparent in the unbalance of convective heat transfer in a water boiler. Pressurized combustion has, since the middle of the nineteenth century, been postulated as a means of increasing the gas-side convective heat transfer to more nearly correspond with the water-side rate. Gas turbines, in the form of turbine-driven supercharged boilers, have been made, but without significant commercial success, in Europe and America. Modern gas turbines are employed in total-energy systems but because of the premium value of their shaft power output, additional heat exchangers must have the minimum pressure loss and therefore conventional heat-transfer criteria apply. Small turbine-driven superchargers are now mass produced for automotive diesel engines and particularly with the availability of natural gas the feasibility of pressurized combustion by their use justifies re-appraisal. Although these turbochargers have little value as gas-turbine power units the margin of turbine output over compressor power absorption can be employed to improve heat-exchanger convective heat-transfer rates significantly. The provision of a second compressor in the rotor system enables a stoichiometric air and gaseous fuel charge to be induced into a simple pre-mixed combustor thus preserving the low-cost aspect of the turbocharger and providing improved control and safety in a very durable gas-turbine device. The addition of a simple after-burner allows total combustion at relatively low excess air rates. The arguments leading to the foregoing design are presented and some of the more important product developments are described. Examination of the wider application potential of such low-cost turbomachinery indicates prospects for their employment in diverse uses particularly where high heat-transfer rates are desirable.

Convective Heat Transfer Enhancement Due to Intermittency in an Impinging Jet

1993 ◽  
Vol 115 (1) ◽  
pp. 91-98 ◽  
Author(s):  
D. A. Zumbrunnen ◽  
M. Aziz
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Impinging Jets ◽  
Transfer Coefficients ◽  
Stagnation Line ◽  
High Heat Transfer ◽  
Short Period

An experimental investigation has been performed to study the effect of flow intermittency on convective heat transfer to a planar water jet impinging on a constant heat flux surface. Enhanced heat transfer was achieved by periodically restarting an impinging flow and thereby forcing renewal of the hydrodynamic and thermal boundary layers. Although convective heat transfer was less effective during a short period when flow was interrupted, high heat transfer rates, which immediately follow initial wetting, prevailed above a threshold frequency, and a net enhancement occurred. Experiments with intermittent flows yielded enhancements in convective heat transfer coefficients of nearly a factor of two, and theoretical considerations suggest that higher enhancements can be achieved by increasing the frequency of the intermittency. Enhancements need not result in an increased pressure drop within a flow system, since flow interruptions can be induced beyond a nozzle exit. Experimental results are presented for both the steady and intermittent impinging jets at distances up to seven jet widths from the stagnation line. A theoretical model of the transient boundary layer response is used to reveal parameters that govern the measured enhancements. A useful correlation is also provided of local heat transfer results for steadily impinging jets.

APPLICATION OF ADSORPTION METHOD FOR DETERMINATION OF LOCAL CONVECTIVE HEAT TRANSFER RATES

1974 ◽  
Author(s):  
S. Koncar-Djurdjevic ◽  
M. Mitrovic ◽  
S. Cvijovic ◽  
G. Popovic ◽  
Dimitrije Voronjec
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Adsorption Method ◽  
Transfer Rates
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