Comparative Study of Conjugate Heat Transfer in Uniform and Diverging Cross-Section Microchannels

2018 ◽  
pp. 76-95
Author(s):  
Yogesh K. Prajapati
Keyword(s):  
Heat Transfer ◽  
Comparative Study ◽  
Cross Section ◽  
Heat Transfer Performance ◽  
Flow Direction ◽  
Copper Substrate ◽  
Convection Heat Transfer ◽  
Constant Heat Flux ◽  
Transfer Performance ◽  
Diverging Channel

This chapter covers single-phase heat transfer analysis in microchannel heat sink relevant to electronic cooling application. In order to estimate the correct heat transfer performance, it is required to consider both, conduction and convection. Hence, conjugate analysis of heat transfer has been considered where both conduction and convection heat transfer are calculated as a part of solution. Two different configurations of microchannels namely, uniform and diverging cross-section have been considered individually on different copper substrate. A copper substrate of dimension 25×0.9×4 mm has been used to generate microchannel. Inlet cross-section (0.4×0.75 mm) of both channels has been kept equal however; cross-section of diverging channel keeps on increasing as width is continuously increasing along the flow direction. A constant heat flux of 250 kW/m2 has been provided from the bottom. Comparative study has been done to analyse the heat transfer performance of both the configurations of microchannels.

EXPERIMENTAL STUDY ON THERMAL TRANSPORT PHENOMENON OF NANOFLUIDS AS WORKING FLUID IN HEAT EXCHANGER

2014 ◽  
Vol 22 (01) ◽  
pp. 1450005 ◽  
Author(s):  
SHUICHI TORII
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Performance ◽  
Pure Water ◽  
Horizontal Tube ◽  
Constant Heat Flux ◽  
Working Fluid ◽  
Transfer Performance ◽  
Nanoparticles Concentration ◽  
Transfer Behavior

This paper aims to study the convective heat transfer behavior of aqueous suspensions of nanoparticles flowing through a horizontal tube heated under constant heat flux condition. Consideration is given to the effects of particle concentration and Reynolds number on heat transfer enhancement and the possibility of nanofluids as the working fluid in various heat exchangers. It is found that (i) significant enhancement of heat transfer performance due to suspension of nanoparticles in the circular tube flow is observed in comparison with pure water as the working fluid, (ii) enhancement is intensified with an increase in the Reynolds number and the nanoparticles concentration, and (iii) substantial amplification of heat transfer performance is not attributed purely to the enhancement of thermal conductivity due to suspension of nanoparticles.

3D Printed Architected Heat Sinks Cooling Performance in Free and Forced Convection Environments

2020 ◽  
Author(s):  
Mohamed I. Hassan Ali ◽  
Oraib Al-Ketan ◽  
Mohamad Khalil ◽  
Nada Baobaid ◽  
Kamran Khan ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Forced Convection ◽  
Heat Transfer Performance ◽  
Convection Heat Transfer ◽  
Heat Sinks ◽  
Cfd Modeling ◽  
Transfer Performance ◽  
Convection Heat ◽  
Performance Study

Abstract In this work, we extend our heat transfer performance study on our proposed new and novel 3D printable architected heat sinks with geometrically complex structures based on triply periodic minimal surfaces (TPMS). Computational fluid dynamics (CFD) modeling is used to assess the effect of porosity distribution, heat load, and isothermal boundary condition on the performance of the proposed TPMS-based heat sinks in active cooling using natural and forced convection heat transfer environments. The convection heat transfer coefficient, surface temperature, pressure drop are predicted using CFD method. The CFD model is validated using experimental results for the pressure drop and is verified by standard analytical results. Three TPMS structures are investigated in different orientations. Dimensionless heat transfer groups are developed to globalize the heat transfer performance of the proposed heat sinks.

Heat Transfer and Pressure Drop of Lotus-Type Porous Metals

2013 ◽  
Vol 135 (7) ◽  
Author(s):  
Kenshiro Muramatsu ◽  
Takuya Ide ◽  
Hideo Nakajima ◽  
John K. Eaton
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Transfer Performance ◽  
Flow Direction ◽  
Heated Surface ◽  
Metal Foams ◽  
Thin Layers ◽  
Random Structure ◽  
Transfer Performance ◽  
Layer Spacing

Metal foams are of interest for heat transfer applications because of their high surface-to-volume ratio and high convective heat transfer coefficients. However, conventional open-cell foams have high pressure drop and low net thermal conductivity in the direction normal to a heated surface due to the fully random structure. This paper examines heat transfer elements made by stacking thin layers of lotus metal which have many small pores aligned in the flow direction. The reduction in randomness reduces the pressure drop and increases the thermal conduction compared to conventional metal foams. Experimental results are presented for the heat transfer performance of two types of lotus metal fins, one with a deterministic pattern of machined holes and one with a random hole pattern made by a continuous casting technique. The layer spacing, the hole diameter, the porosity, and the flow Reynolds number were all varied. The measurements show that spacing between fin layers and the relative alignment of pores in successive fins can have a substantial effect on the heat transfer performance.

scholarly journals Heat Transfer Performance of Different Fluids During Natural Convection in Enclosures with Varying Aspect Ratios

2021 ◽  
Vol 287 ◽  
pp. 03010
Author(s):  
Rajashekhar Pendyala ◽  
Suhaib Umer Ilyas ◽  
Yean Sang Wong
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Natural Convection ◽  
Heat Transfer Performance ◽  
Convection Heat Transfer ◽  
Heat Transfer Process ◽  
Natural Convection Heat Transfer ◽  
Transfer Performance ◽  
Convection Heat ◽  
Aspect Ratios

The heat transfer process takes place in numerous applications through the natural convection of fluids. Investigations of the natural convection heat transfer in enclosures have gained vital importance in the last decade for the improvement in thermal performance and design of the heating/cooling systems. Aspect ratios (AR=height/length) of the enclosures are one of the crucial factors during the natural convection heat transfer process. The investigated fluids consisting of air, water, engine oil, mercury, and glycerine have numerous engineering applications. Heat transfer and fluid flow characteristics are studied in 3-dimensional rectangular enclosures with varying aspect ratios (0.125 to 150) using computational fluid dynamics (CFD) simulations. Studies are carried out using the five different fluids having Prandtl number range 0.01 to 4500 in rectangular enclosures with the hot and cold surface with varying temperature difference 20K to 100K. The Nusselt number and heat transfer coefficients are estimated at all conditions to understand the dependency of ARs on the heat transfer performance of selected fluids. Temperature and velocity profiles are compared to study the flow pattern of different fluids during natural convection. The Nusselt number correlations are developed in terms of aspect ratio and Rayleigh number to signify the natural convection heat transfer performance.

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