The entropy generation for a rotating sphere under uniform heat flux boundary condition in forced‐convection flow

2009 ◽  
Vol 19 (3/4) ◽  
pp. 396-410 ◽  
Author(s):  
Mohamed A. Antar ◽  
Maged A.I. El‐Shaarawi
Keyword(s):  
Boundary Condition ◽  
Heat Flux ◽  
Forced Convection ◽  
Entropy Generation ◽  
Convection Flow ◽  
Uniform Heat Flux ◽  
Flux Boundary Condition ◽  
Rotating Sphere ◽  
Forced Convection Flow ◽  
Heat Flux Boundary Condition

Three Dimensional Numerical Simulation of Gas Heat Transfer in Rectangular Microchannels

2010 ◽  
Author(s):  
Xiaohong Yan ◽  
Qiuwang Wang
Keyword(s):  
Heat Transfer ◽  
Boundary Condition ◽  
Heat Flux ◽  
Aspect Ratio ◽  
Wall Temperature ◽  
Three Dimensional ◽  
Uniform Heat Flux ◽  
Flux Boundary Condition ◽  
Uniform Heat ◽  
Heat Flux Boundary Condition

Rectangular microchannel is the typical component of the micro heat exchangers and micro heat sinks. Three-dimensional compressible Navier-Stokes equations are solved for gas flow and heat transfer in microchannels under uniform heat flux boundary condition. The numerical methodology is based on the control volume SIMPLE scheme. It is found that the heat removal characteristic for compressible flow is better than the incompressible flow and it is not suitable to use conventionally defined Nu to measure the heat transfer characteristic for compressible heat transfer. The effect of the aspect ratio (width to height) on the cross-sectional averaged wall temperature and the Nu is negligible under the uniform heat flux boundary condition. However, the local uniformity of the wall temperature is significantly influenced by the aspect ratio. The square cross-section exhibits the best local uniformity of the wall temperature.

Boundary Conditions and Integrated Sensors in Microchannel Convective Heat Transfer

2006 ◽  
Author(s):  
Man Lee ◽  
Luthur Siu Lin Cheung ◽  
Yi-Kuen Lee ◽  
Yitshak Zohar
Keyword(s):  
Boundary Condition ◽  
Heat Flux ◽  
Boundary Conditions ◽  
Pressure Sensors ◽  
Uniform Heat Flux ◽  
Phase Flow ◽  
Convective Boiling ◽  
Flux Boundary Condition ◽  
Heat Flux Boundary Condition ◽  
Temperature And Pressure

A microchannel heat sink, integrated with pressure and temperature microsensors, is fabricated to study convective boiling under uniform heat flux boundary condition. Utilizing a wafer bond and etch back technology, the heat source, temperature and pressure sensors are separated from the fluid flow by a membrane only 1.5μm in thickness; thus, allowing good control of the thermal boundary conditions. Temperature and pressure distributions for various power levels and flow rates are measured while, simultaneously, the flow patterns are recorded. Single-phase flow results, compared with numerical simulations, confirm that the heat flux boundary condition is indeed nearly uniform. The sensor arrays, particularly for two-phase flow, provide the spatial and temporal dependence of both the temperature and pressures fields.

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