Thermo-economic Limitations of Ambient Heat Rejection in Vertical Fin Arrays With Buoyancy-Driven Flow Enhancement Through the Chimney Effect

2016 ◽  
Vol 9 (1) ◽  
Author(s):  
Noris Gallandat ◽  
J. Rhett Mayor
Keyword(s):  
Heat Flux ◽  
Heat Sink ◽  
Cooling Power ◽  
Heat Rejection ◽  
One Dimensional ◽  
Power Enhancement ◽  
Flow Enhancement ◽  
The Cost ◽  
Heat Sink Design ◽  
Chimney Effect

This paper presents the thermo-economic limits of ambient heat rejection in vertical fin arrays with buoyancy-driven flow enhancement through the chimney effect. A one-dimensional semi-analytical thermo-fluidic model is developed to assess the cooling power enhancement of the proposed heat sink design. A bi-objective optimization is performed utilizing genetic algorithm to present the tradeoffs between the cost and the thermal performance of a heat sink. For the considered baseplate geometry, the maximal cooling power without a chimney amounts 1540 W at a heat flux of 1.03 W/cm2. By adding a chimney up to 2.5 m high, the cooling power is increased by 46% to 2250 W at a heat flux of 1.50 W/cm2.

The Development of an Integrated Fan and Heat Sink Solution for Thermal Management in Low Profile Applications

2006 ◽  
Author(s):  
Ed Walsh ◽  
Ronan Grimes
Keyword(s):  
Heat Flux ◽  
Thermal Management ◽  
Heat Sink ◽  
Heat Sinks ◽  
Portable Electronics ◽  
Low Profile ◽  
Convection Cooling ◽  
New Methodologies ◽  
Heat Sink Design ◽  
Management Issues

The increasing heat flux densities from portable electronics are leading to new methodologies being implemented to provide thermal management within such devices. Many technologies are under development to transport heat within electronic equipment to allow it to be transported into the surroundings via conduction, natural convection and radiation. Few have considered the approach of implementing a forced convection cooling solution in such devices. This work addresses the potential of a low profile integrated fan and heat sink solution to electronics thermal management issues of the future, particularly focusing upon possible solutions in low profile portable electronics. We investigate two heat sink designs with mini channel features, applicable to low profile applications. The thermal performance of the heat sinks is seen to differ by approximately 40% and highlights the importance of efficient heat sink design at this scale.

scholarly journals A Novel Heat Sink Design and Prototyping for LED Desk Lamps

2015 ◽  
Vol 2015 ◽  
pp. 1-8
Author(s):  
Li-Ming Chu ◽  
Wei-Chin Chang ◽  
Ting Hsuan Huang
Keyword(s):  
Heat Sink ◽  
Light Emitting Diode ◽  
Base Plate ◽  
Life Time ◽  
Heat Sinks ◽  
Light Emitting ◽  
Lighting Device ◽  
Different Types ◽  
Heat Sink Design ◽  
Chimney Effect

Light-emitting diode (LED) is a modern lighting device. If the heat dissipating mechanism of LED desk lamp is not well designed, the induced high temperature will cause the reduction of illumination and life time of lamp. Therefore, the heat sink design becomes a key technology for LED lighting device. This study developed a methodology to design and analyze a heat sink for LED cooling. Four different types of heat sinks with fins in longitudinal or transverse directions and with or without vents on the base plate were compared. By using the CFD software FLUENT, heat flux and temperature around the heat sink were analyzed, and the surface temperature distribution was also investigated. The simulation outcomes were compared with experiments results to verify analysis accuracy. The comparisons show only slight differences, and the deviations were less than 4.0%. For cooling LED desk lamp, the design of using 12 vents on both sides of heat sink through natural convection to create the chimney effect was adopted; consequently, the temperature dropped 5°C in average. This design can also reduce the material of heat sink, LED lamp weight, and production cost.

Thermo-Economic Limitations of Passive Air-Cooled Ambient Heat Rejection Systems

2014 ◽  
Author(s):  
Noris Gallandat ◽  
J. Rhett Mayor
Keyword(s):  
Heat Flux ◽  
Natural Convection ◽  
Thermal Resistance ◽  
Pareto Front ◽  
Cost Effective ◽  
Cooling Power ◽  
Economic Optimization ◽  
Heat Rejection ◽  
Thermal Requirements ◽  
Two Parameters

This paper presents the preliminary results of a thermo economic optimization of passive air-cooled ambient heat rejection systems. Although a lot of effort has been put into the thermal efficiency of various cooling technologies, there is a need for a comprehensive thermo-economic study cross comparing the different options. This study considers passive ambient heat rejection from bonded and extruded fin arrays. The outcome is a general Pareto front showing the limitations of different passive cooling technologies such as natural convection through extruded and bonded fin arrays or enhanced heat transfer via chimney effect. The obtained Pareto front allows making cost effective decisions regarding which technology to implement depending on the thermal requirements of the system. A bi-objective optimization is carried out using genetic algorithms. The two parameters to minimize are the overall thermal resistance and the total cost of the system. It is shown that, generally, there is a negative correlation between the cost of the system and the thermal resistance. At low heat flux, natural convection through extruded fin arrays is the most economical choice. As more stringent thermal loads act on a system, the thermal resistance of the heat sink can be reduced at an additional cost by enhancement of convective heat transport through buoyancy-driven flows. For the considered geometry, the maximal cooling power without a chimney amounts 1887W at a heat flux of 0.87W/cm2. By adding a 5m chimney, a 43% increase in the cooling power is reached, allowing the removal of up to 2695W at a heat flux of 1.26 W/cm2.

Investigation of On-Chip Hot Spot Cooling Using Microchannel Heat Sink

2013 ◽  
Vol 455 ◽  
pp. 466-469
Author(s):  
Yun Chuan Wu ◽  
Shang Long Xu ◽  
Chao Wang
Keyword(s):  
Heat Flux ◽  
Heat Sink ◽  
Hot Spots ◽  
Hot Spot ◽  
High Heat ◽  
High Heat Flux ◽  
Microchannel Heat Sink ◽  
Three Dimensional Model ◽  
Spot Cooling ◽  
On Chip

With the increase of performance demands, the nonuniformity of on-chip power dissipation becomes greater, causing localized high heat flux hot spots that can degrade the processor performance and reliability. In this paper, a three-dimensional model of the copper microchannel heat sink, with hot spot heating and background heating on the back, was developed and used for numerical simulation to predict the hot spot cooling performance. The hot spot is cooled by localized cross channels. The pressure drop, thermal resistance and effects of hot spot heat flux and fluid flow velocity on the cooling of on-chip hot spots, are investigated in detail.

Statistical Mechanics of Thermotransport of a Heavy Impurity in an Insulating Solid

1971 ◽  
Vol 26 (1) ◽  
pp. 10-17 ◽  
Author(s):  
A. R. Allnatt
Keyword(s):  
Heat Flux ◽  
Time Correlation ◽  
Three Dimensions ◽  
Time Correlation Functions ◽  
Single Vacancy ◽  
One Dimensional ◽  
Enthalpy Of Activation ◽  
Heavy Impurity ◽  
The One ◽  
Non Equilibrium

AbstractA kinetic equation is derived for the singlet distribution function for a heavy impurity in a lattice of lighter atoms in a temperature gradient. In the one dimensional case the equation can be solved to find formal expressions for the jump probability and hence the heat of transport, q*. for a single vacancy jump of the impurity, q* is the sum of the enthalpy of activation, a term involving only averaging in an equilibrium ensemble, and two non-equilibrium terms in­volving time correlation functions. The most important non-equilibrium term concerns the cor­relation between the force on the impurity and a microscopic heat flux. A plausible extension to three dimensions is suggested and the relation to earlier isothermal and non-isothermal theories is indicated

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