Time-Dependent Transpiration Heat Transfer in Porous Cylinders

1974 ◽  
Vol 96 (2) ◽  
pp. 218-224 ◽  
Author(s):  
D. M. Burch ◽  
B. A. Peavy ◽  
R. W. Allen
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Chemical Reactor ◽  
Analytic Solutions ◽  
Transient Temperature ◽  
Transfer Coefficients ◽  
Forced Convective Heat Transfer ◽  
Heat Transfer Coefficients ◽  
Transient Temperature Distribution

This paper investigates the transient temperature distribution within transpiration-heated and -cooled porous tubes that occur after a step increase in the rate of convective heat transfer at one of the tube surfaces. Analytic solutions are presented for transpiration cooling, catalytic chemical reactor, and tubular regenerator applications. These solutions include the effect of forced convective heat transfer at both tube surfaces where conventional heat-transfer coefficients are used to define the boundary conditions.

Study on Forced Convective Heat Transfer of FC-72 in Vertical Small Tubes

2020 ◽  
Vol 12 (6) ◽  
Author(s):  
Yantao Li ◽  
Yulong Ji ◽  
Katsuya Fukuda ◽  
Qiusheng Liu
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convection Heat Transfer ◽  
Bulk Liquid ◽  
Transfer Coefficients ◽  
Forced Convective Heat Transfer ◽  
Heat Transfer Coefficients ◽  
Convective Heat Transfer Coefficients

Abstract This paper presents an experimental investigation of the forced convective heat transfer of FC-72 in vertical tubes at various velocities, inlet temperatures, and tube sizes. Exponentially escalating heat inputs were supplied to the small tubes with inner diameters of 1, 1.8, and 2.8 mm and effective heated lengths between 30.1 and 50.2 mm. The exponential periods of heat input range from 6.4 to 15.5 s. The experimental data suggest that the convective heat transfer coefficients increase with an increase in flow velocity and µ/µw (refers to the viscosity evaluated at the bulk liquid temperature over the liquid viscosity estimated at the tube inner surface temperature). When tube diameter and the ratio of effective heated length to inner diameter decrease, the convective heat transfer coefficients increase as well. The experimental data were nondimensionalized to explore the effect of Reynolds number (Re) on forced convection heat transfer coefficient. It was found that the Nusselt numbers (Nu) are influenced by the Re for d = 2.8 mm in the same pattern as the conventional correlations. However, the dependences of Nu on Re for d = 1 and 1.8 mm show different trends. It means that the conventional heat transfer correlations are inadequate to predict the forced convective heat transfer in minichannels. The experimental data for tubes with diameters of 1, 1.8, and 2.8 mm were well correlated separately. And, the data agree with the proposed correlations within ±15%.

scholarly journals Experimental Investigation into the Forced Convective Heat Transfer of Aqueous Fe3O4 Nanofluids under Transition Region

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Jie Ma ◽  
Yinchen Xu ◽  
Wenlie Li ◽  
Jiantao Zhao ◽  
Shuping Zhang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Transition Region ◽  
Convective Heat ◽  
Reynolds Numbers ◽  
Axial Distance ◽  
Transfer Coefficients ◽  
Forced Convective Heat Transfer ◽  
Heat Transfer Coefficients ◽  
Initial Expectation

The forced convective heat transfer (FCHT) properties of nanofluids, made of Fe3O4 nanomaterials and deionized water, are firstly measured by a self-made forced convective heat transfer apparatus. The nanofluid flows through a horizontal copper tube in the transition region with Reynolds numbers in the range of 2500–5000. Some parameters including Reynolds number, axial distance, and mass concentration are also investigated. The preliminary results are firstly presented that the heat transfer coefficients of Fe3O4 nanofluids systematically decrease with increasing concentration of nanoparticles under transition region which contradicts the initial expectation.

Use or Transient Temperature Measurements to Determine Combustor Liner Heat Transfer Coefficients

1979 ◽  
Author(s):  
Barry Schlein
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Gas Turbine ◽  
Convective Heat ◽  
Numerical Solutions ◽  
Temperature Measurements ◽  
Transient Temperature ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Convective Heat Transfer Coefficients

The use of transient temperature measurements to determine convective heat transfer coefficients is extended to the more complex environment of the gas turbine combustion chamber. Numerical solutions to a transient liner wall heat balance demonstrate that the rate of metal temperature with time is exponential and that the rate is only a function of the convective heat transfer coefficients. Data taken during a snap acceleration of a gas turbine confirms the exponential temperature response. The combination of numerical analysis and transient temperature measurements provides an approximate method of determining linear heat transfer coefficients.

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