Natural Convection in Two-Dimensional Horizontal Channel With Heat Sources

2003 ◽  
Author(s):  
Tito Dias ◽  
Luiz Fernando Milanez
Keyword(s):  
Natural Convection ◽  
Flux Ratio ◽  
Horizontal Channel ◽  
Maximum Temperature ◽  
Computational Domain ◽  
Heat Sources ◽  
Two Dimensional ◽  
Temperature Excess ◽  
Fluid Properties ◽  
Laminar Natural Convection

Laminar natural convection in a two-dimensional horizontal channel is very important in laptop design, since optimizing the utilization of the cooler saves energy from the battery. In this work, this configuration has been numerically studied. Three cases were studied according to the position of the heat sources in the lower wall, upper wall and both. The computational domain consisted of two adiabatic walls where the heat sources were positioned, and two open boundaries, where the manometric pressure and normal gradient of velocity were zero. Ambient temperature was prescribed for the entering fluid and zero normal gradient for the exiting fluid. Fluid properties were assumed constant except for the density change with temperature on the buoyancy term. The influence of the modified Rayleigh number, position of the heat sources and heat flux ratio between the sources were analyzed for Prandtl number of 0.7. The maximum temperature excess on the heat source is lower for the case with two heat sources and Ra = 104. This preliminary study showed the existence of a minimum value of the excess temperature for the studies aspect ratio (0.1).

Cooling of a Multichip Electronic Module by Means of Confined Two-Dimensional Jets of Dielectric Liquid

1990 ◽  
Vol 112 (4) ◽  
pp. 891-898 ◽  
Author(s):  
D. C. Wadsworth ◽  
I. Mudawar
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer Coefficient ◽  
Channel Height ◽  
Heat Sources ◽  
Two Dimensional ◽  
Chip Surface ◽  
Rectangular Slot ◽  
Fluid Properties ◽  
Cooling Module ◽  
Heater Length

Experiments were performed to investigate single-phase heat transfer from a smooth 12.7 × 12.7 mm2 simulated chip to a two-dimensional jet of dielectric Fluorinert FC-72 liquid issuing from a thin rectangular slot into a channel confined between the chip surface and nozzle plate. The effects of jet width, confinement channel height, and impingement velocity have been examined. Channel height had a negligible effect on the heat transfer performance of the jet for the conditions of the present study. A correlation for the convective heat transfer coefficient is presented as a function of jet width, heater length, flow velocity, and fluid properties. A self-contained multichip cooling module consisting of a 3 × 3 array of heat sources confirmed the uniformity and predictability of cooling for each of the nine chips, and proved the cooling module is well suited for packaging large arrays of high-power density chips.

Optimal Distribution of Discrete Heat Sources Under Mixed Convection—A Heuristic Approach

2014 ◽  
Vol 136 (10) ◽  
Author(s):  
Tapano Kumar Hotta ◽  
C. Balaji ◽  
S. P. Venkateshan
Keyword(s):  
Heat Transfer ◽  
Mixed Convection ◽  
Optimal Configuration ◽  
Surface Radiation ◽  
Horizontal Wind ◽  
Maximum Temperature ◽  
Heat Sources ◽  
Discrete Heat Sources ◽  
Temperature Excess ◽  
Effect Of Surface

Steady state experiments are conducted in a low speed horizontal wind tunnel under mixed convection for five discrete heat sources (aluminum) of nonidentical sizes arranged at different positions on a substrate board (bakelite) to determine the optimal configuration. The optimal configuration is one for which the maximum temperature excess (difference between the maximum temperature among the heat sources of that configuration, and the ambient temperature) is the lowest among all the other possible configurations and is determined by a heuristic nondimensional geometric parameter λ. The maximum temperature excess is found to decrease with λ, signifying an increase in heat transfer coefficient. In view of this, the configuration with highest λ is deemed to be the optimal one. The effect of surface radiation on the heat transfer characteristic of heat sources is also studied by painting their surface with black, which reduces their temperature by as much as 12%. An empirical correlation is developed for the nondimensional maximum temperature excess (θ) in terms of λ, by taking into account the effect of surface radiation. The correlation when applied for highest λ of the configuration returns the minimum value of θ at the optimal condition, which is a key engineering quantity that is sought in problems of this class.

Laminar Natural Convection in a Discretely Heated Cavity: I—Assessment of Three-Dimensional Effects

1995 ◽  
Vol 117 (4) ◽  
pp. 902-909 ◽  
Author(s):  
T. J. Heindel ◽  
S. Ramadhyani ◽  
F. P. Incropera
Keyword(s):  
Natural Convection ◽  
Vertical Wall ◽  
Three Dimensional ◽  
Companion Paper ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Nusselt Numbers ◽  
Aspect Ratios ◽  
Laminar Natural Convection

Two and three-dimensional calculations have been performed for laminar natural convection induced by a 3 × 3 array of discrete heat sources flush-mounted to one vertical wall of a rectangular cavity whose opposite wall was isothermally cooled. Edge effects predicted by the three-dimensional model yielded local and average Nusselt numbers that exceeded those obtained from the two-dimensional model, as well as average surface temperatures that were smaller than the two-dimensional predictions. For heater aspect ratios Ahtr ≲ 3, average Nusselt numbers increased with decreasing Ahtr. However, for Ahtr ≳ 3, the two and three-dimensional predictions were within 5 percent of each other and results were approximately independent of Ahtr. In a companion paper (Heindel et al., 1995a), predictions are compared with experimental results and heat transfer correlations are developed.

Simulation Studies on Two-Dimensional Electronic Board with Multiple Non Identical Heat Sources

2014 ◽  
Vol 592-594 ◽  
pp. 1776-1783
Author(s):  
Narasimha Suri Tinnaluri ◽  
Nageswara Reddy Pereddy ◽  
R. Ch. Sastry Malladi ◽  
Pinjala Tejo Murthi
Keyword(s):  
Temperature Distribution ◽  
Partial Differential Equations ◽  
Energy Balance ◽  
Differential Equations ◽  
Maximum Temperature ◽  
Heat Sources ◽  
Two Dimensional ◽  
Simulation Studies ◽  
Partial Differential ◽  
Electronic Board

The present paper reports results of simulation studies on combined conduction – convection – radiation from two dimensional electronic board equipped with three discrete non identical heat sources. The three non identical heat sources are located across the board. The heat generated in the three heat sources is conducted across the board subsequently getting dissipated by convection and radiation. Air, a radiatively transparent medium, is considered to be the cooling agent. The governing partial differential equations for temperature distribution in the entire computational domain are obtained by appropriate energy balance between the heat generated, convected and radiated. The non linear partial differential equations deduced as above are discretized using finite difference method. The resulting algebraic equations are solved using Gauss - Seidel iterative method. A computer code in C++ is written to solve the problem. A thorough energy balance test and grid study has been performed to freeze on appropriate grid size. The effect of thermal conductivity, surface emissivity and convection heat transfer coefficient on local temperature distribution and maximum temperature distribution of the electronic board are demonstrated exhaustively. Keywords: Surface Radiation, Conduction, Convection, Electronic Board, identical Heat sources.

Numerical Computation of Nonstationary Aerodynamics of Flat Plate Cascades in Compressible Flow

1976 ◽  
Vol 98 (2) ◽  
pp. 165-170 ◽  
Author(s):  
R. H. Ni ◽  
F. Sisto
Keyword(s):  
Flat Plate ◽  
Numerical Computation ◽  
Compressible Flow ◽  
Computational Domain ◽  
Two Dimensional ◽  
Order Of Accuracy ◽  
Fluid Properties ◽  
Time Marching ◽  
Interblade Phase Angle ◽  
Good Agreement

The “time marching” technique is successfully applied to the numerical computation of the nonstationary aerodynamics of a flat plate cascade for compressible flow of either subsonic or supersonic nature. The unsteady perturbation amplitudes of fluid properties are used as the dependent variables so that the computational domain can be reduced to a two-dimensional channel guided by two adjacent blades for any interblade phase angle. A new method of handling the boundary condition is developed in which the order of accuracy for the boundary points will be the same as the interior points. The wake region behind the trailing edge of each blade is treated as a “slip plane” as done in two-dimensional steady state supersonic flow. Results are in good agreement with existing analytical solutions.

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