Experimental Thermal Characterization of Pin Fin Heat Sinks With Top and Side Bypass

2005 ◽  
Author(s):  
Ning Lei ◽  
Alfonso Ortega
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Transfer Coefficient ◽  
Thermal Resistance ◽  
Transfer Coefficient ◽  
Cross Section ◽  
Heat Sinks ◽  
Average Heat Transfer Coefficient ◽  
Average Heat ◽  
Pin Fin

Extensive tests were conducted to obtain thermal characteristics of pin fin heat sinks with pins of square cross-section under different top and side bypass conditions. A consistent set of aluminum heat sinks with constant planform area and variable pitch were utilized. The heat sinks were tested in an adjustable cross-section wind tunnel, which provides 0 to 1 top and 0 to 10 side clearance ratios. The base temperature of the heat sinks was measured under constant heat flux. The overall thermal resistance and average heat transfer coefficient of the heat sinks were calculated and the influence of top and side bypass was explored. The thermal experimental data were consistent with the previous hydraulic experimental data. With the increase of flow velocity, flow transition from laminar to turbulent flow was revealed by the thermal resistance data. It was found that the average heat transfer coefficient depends strongly on the flow velocity through the heat sinks. Heat sinks with side clearance only result in smaller overall thermal resistance compared to top clearance only at the same clearance ratio. In some cases, the heat sinks with a small side clearance had better thermal performance than the same heat sinks without clearance. The empirical equation for infinitely long tube bundles of circular cross-section was used to correlate the thermal experimental data.

scholarly journals Experimental analysis of parallel plate and crosscut pin fin heat sinks for electronic cooling applications

2010 ◽  
Vol 14 (1) ◽  
pp. 147-156 ◽  
Author(s):  
Harish Sivasankaran ◽  
Godson Asirvatham ◽  
Jefferson Bose ◽  
Bensely Albert
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Parallel Plate ◽  
Electronic Cooling ◽  
Heat Sinks ◽  
Average Heat Transfer Coefficient ◽  
Average Heat ◽  
Pin Fin ◽  
Pin Fins

Experimental investigation of parallel plate fin and the crosscut pin fin heat sinks where the heating element placed asymmetrically is performed. Theoretical calculations were done and compared with the experimental results. A comparative study was made based on their efficiencies, heat transfer coefficient, and the thermal performance. From the experimental results it was found that the average heat transfer coefficient of parallel plate fins is higher than that of crosscut pin fins with many perforations. However the performance efficiency of both the crosscut pin fins and parallel plate fins is similar. A hybrid approach was employed to significantly optimize the distance between the fan and heat sink for parallel plate and crosscut pin fins. Parallel plate heat sink with an average heat transfer coefficient of 46 W/m?K placed at an optimum fan distance of 40-60 mm is selected as the suitable choice for the micro-electronic cooling when the heating element is placed asymmetrically.

The Thermal Resistance of Pin Fin Heat Sinks in Transverse Flow

2003 ◽  
Author(s):  
Sukhvinder Kang ◽  
Maurice Holahan
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Transfer Coefficient ◽  
Thermal Resistance ◽  
Transfer Coefficient ◽  
Building Blocks ◽  
Heat Sinks ◽  
Cfd Simulations ◽  
Pin Fin ◽  
Thermal Wake

This paper presents a physics based analytical model to predict the thermal behavior of pin fin heat sinks in transverse forced flow. The key feature of the model is the recognition that unlike plate fins, streamwise conduction does not occur in pin fin heat sinks. Thus, the heat transfer from each fin depends on its local air temperature or adiabatic temperature and the local adiabatic heat transfer coefficient. Both experimental data and simplified CFD simulations are used to develop the two building blocks of the model, the thermal wake function and the adiabatic heat transfer coefficient. These building blocks are then used to include the effect of the thermal wake from upstream fins on the adiabatic temperature of downstream fins in determining the fin-by-fin heat transfer within the pin fin array. This approach captures the essential physics of the flow and heat transport within the fin array and yields an accurate model for predicting the thermal resistance of pin fin heat sinks. Model predictions are compared with existing experimental data and CFD simulations. The model is expected to provide a sound basis for a consistent performance comparison with plate fin heat sinks.

Experimental and Numerical Study on the Convective Heat Transfer and Pressure Loss in Rectangular Ducts With Inclined Pin-Fin on a Wavy Endwall

2012 ◽  
Author(s):  
K. Takeishi ◽  
Y. Oda ◽  
Y. Miyake ◽  
Y. Motoda
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Pressure Loss ◽  
Numerical Study ◽  
Average Heat Transfer Coefficient ◽  
Average Heat ◽  
Pin Fin ◽  
Pin Fins

Local endwall heat transfer characteristics and overall pressure loss of normal and inclined pin fins arrayed in rectangular ducts with flat and wavy endwalls have been investigated to improve the cooling efficiency of jet engine combustor liners. The detailed time-mean local Nusselt number profiles were measured using a naphthalene sublimation method based on the heat/mass transfer analogy. Four kinds of angled pin fins (−45, 0, and +45 degrees with a flat endwall, and −45 degrees with a wavy endwall) were tested and compared with each other. As a result, the average heat transfer coefficient on the flat endwall of normal pin fins was higher than that of the angled pin fins. The average heat transfer coefficient of −45-degree inclined pin fins with a wavy endwall is the same or a little higher than the heat transfer coefficient of those with a flat endwall; however, the pressure loss of the −45-degree inclined pin fins with a wavy endwall is less than the pressure loss of those with a flat endwall. Corresponding numerical simulations using Large Eddy Simulation (LES) with the Mixed Time Scale (MTS) model have been also conducted at Red = 1000 for fully developed regions, and the results have shown good quantitative agreement with mass transfer experiments. It can be concluded that wavy endwalls can realize better heat transfer with less pressure loss as long as the aim consists in enhancing endwall heat transfer in inclined pin-fin channels.

Convective Heat Transfer and Pressure Loss in Rectangular Ducts With Inclined Pin-Fin on a Wavy Endwall

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Kenichiro Takeishi ◽  
Yutaka Oda ◽  
Yoshiaki Miyake ◽  
Yusuke Motoda
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Pressure Loss ◽  
Quantitative Agreement ◽  
Average Heat Transfer Coefficient ◽  
Average Heat ◽  
Pin Fin ◽  
Pin Fins

Local endwall heat transfer characteristics and overall pressure loss of normal and inclined pin fins arrayed in rectangular ducts with flat and wavy endwalls have been investigated to improve the cooling efficiency of jet engine combustor liners. The detailed time-mean local Nusselt number profiles were measured using a naphthalene sublimation method based on the heat/mass transfer analogy. Four kinds of angled pin fins (−45, 0, and +45 deg with a flat endwall, and −45 deg with a wavy endwall) were tested and compared with each other. As a result, the average heat transfer coefficient on the flat endwall of normal pin fins was higher than that of the angled pin fins. The average heat transfer coefficient of −45-deg inclined pin fins with a wavy endwall is the same or a little higher than the heat transfer coefficient of those with a flat endwall; however, the pressure loss of the −45-deg inclined pin fins with a wavy endwall is less than the pressure loss of those with a flat endwall. Corresponding numerical simulations using large eddy simulation (LES) with the mixed time scale (MTS) model have been also conducted at Red = 1000 for fully developed regions, and the results have shown good quantitative agreement with mass transfer experiments. It can be concluded that wavy endwalls can realize better heat transfer with less pressure loss as long as the aim consists in enhancing endwall heat transfer in inclined pin-fin channels.

Three Dimensional CFD Conjugate Analysis of Two Inline PLCC Packages Horizontally Mounted

2004 ◽  
Vol 1 (4) ◽  
pp. 244-260 ◽  
Author(s):  
B. Jayakumar ◽  
G. A. Quadir ◽  
M. Z. Abdullah ◽  
K. N. Seetharamu
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Thermal Resistance ◽  
Transfer Coefficient ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Junction Temperature ◽  
Average Heat Transfer Coefficient ◽  
Average Heat ◽  
Air Inlet

A three dimensional conjugate analysis of heat and fluid flow of two 84-pin PLCC packages mounted horizontally on a printed circuit board in a wind tunnel is carried out using a commercial CFD code, FLUENTTM. Various inlet air velocities are used to emulate natural, mixed and forced convection conditions. Some parametric studies are carried out by varying the package chip power, gap between the packages and air inlet velocities. The results are presented in terms of the junction temperature, thermal resistance and top surface average heat transfer coefficient for each package under different operating conditions. The decrease in the junction temperature of the packages with the increase in air inlet velocity is clearly predicted. Further, the leading edge heat transfer coefficient of the packages is always higher than that at the trailing edge for all inlet air velocities considered. It is found that the variation in the package chip power does not influence the average heat transfer coefficient and the thermal resistance of the package at a particular inlet air velocity. Different correlations in terms of the junction temperature as well as the Nusselt number are presented for each package under different convection conditions.

ANALYSIS OF METHODS FOR CALCULATING HEAT TRANSFER IN THERMOELECTRIC COOLING SYSTEMS FOR HEAT-STRESSED ELEMENTS

2021 ◽  
pp. 21-31
Author(s):  
С.В. Бородкин ◽  
А.В. Иванов ◽  
И.Л. Батаронов ◽  
А.В. Кретинин
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Cooling System ◽  
Average Heat Transfer Coefficient ◽  
The Finite Element Method ◽  
Differential Heat ◽  
Average Heat ◽  
Principal Possibility

На основе уравнений теплопереноса в движущейся среде и соотношений теплопередачи в термоэлектрическом охладителе приведен сравнительный анализ методик расчета поля температуры в теплонапряженном элементе. Рассмотрены методики на основе: 1) теплового баланса, 2) среднего коэффициента теплоотдачи, 3) дифференциального коэффициента теплоотдачи, 4) прямого расчета в рамках метода конечных элементов. Установлено, что первые две методики не дают адекватного распределения поля температур, но могут быть полезны для определения принципиальной возможности заданного охлаждения с использованием термоэлектрических элементов. Последние две методики позволяют корректно рассчитать температурное поле, но для использования третьей методики необходим дифференциальный коэффициент теплоотдачи, который может быть найден из расчета по четвертой методике. Сделан вывод о необходимости комбинированного использования методик в общем случае. Методы теплового баланса и среднего коэффициента теплоотдачи позволяют определить принципиальную возможность использования термоэлектрического охлаждения конкретного теплонапряженного элемента (ТЭ). Реальные параметры системы охлаждения должны определяться в рамках комбинации методов дифференциального коэффициента теплоотдачи и конечных элементов (МКЭ). Первый из них позволяет определить теплонапряженные области и рассчитать параметры системы охлаждения, которые обеспечивают тепловую разгрузку этих областей. Второй метод используется для проведения численных экспериментов по определению коэффициента теплоотдачи реальной конструкции The article presents on the basis of the equations of heat transfer in a moving medium and the relations of heat transfer in a thermoelectric cooler, a comparative analysis of methods for calculating the temperature field in a heat-stressed element. We considered methods based on: 1) heat balance, 2) average heat transfer coefficient, 3) differential heat transfer coefficient, 4) direct calculation using the finite element method. We established that the first two methods do not provide an adequate distribution of the temperature field but can be useful for determining the principal possibility of a given cooling using thermoelectric elements. The last two methods allow us to correctly calculate the temperature field; but to use the third method, we need a differential heat transfer coefficient, which can be found from the calculation using the fourth method. We made a conclusion about the need for combined use of methods in a general case. The methods of thermal balance and average heat transfer coefficient allow us to determine the principal possibility of using thermoelectric cooling of a specific heat-stressed element. The actual parameters of the cooling system should be determined using a combination of the differential heat transfer coefficient and the finite element method. The first of them allows us to determine the heat-stressed areas and calculate the parameters of the cooling system that provide thermal discharge of these areas. The second method is used to perform numerical experiments to determine the heat transfer coefficient of a real structure

Experimental and theoretical investigation of heat transfer characteristics of cylindrical heat pipe using Al2O3–SiO2/W-EG hybrid nanofluids by RSM modeling approach

2021 ◽  
Vol 68 (1) ◽  
Author(s):  
R. Vidhya ◽  
T. Balakrishnan ◽  
B. Suresh Kumar
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Transfer Coefficient ◽  
Thermal Resistance ◽  
Transfer Coefficient ◽  
Heat Pipe ◽  
Diffraction Spectrum ◽  
Step Method ◽  
Ceramic Nanoparticles ◽  
Transfer Mechanisms

AbstractNanofluids are emerging two-phase thermal fluids that play a vital part in heat exchangers owing to its heat transfer features. Ceramic nanoparticles aluminium oxide (Al2O3) and silicon dioxide (SiO2) were produced by the sol-gel technique. Characterizations have been done through powder X-ray diffraction spectrum and scanning electron microscopy analysis. Subsequently, few volume concentrations (0.0125–0.1%) of hybrid Al2O3–SiO2 nanofluids were formulated via dispersing both ceramic nanoparticles considered at 50:50 ratio into base fluid combination of 60% distilled water (W) with 40% ethylene glycol (EG) using an ultrasonic-assisted two-step method. Thermal resistance besides heat transfer coefficient have been examined with cylindrical mesh heat pipe reveals that the rise of power input decreases the thermal resistance and inversely increases heat transfer coefficient about 5.54% and 43.16% respectively. Response surface methodology (RSM) has been employed for the investigation of heat pipe experimental data. The significant factors on the various convective heat transfer mechanisms have been identified using the analysis of variance (ANOVA) tool. Finally, the empirical models were developed to forecast the heat transfer mechanisms by regression analysis and validated with experimental data which exposed the models have the best agreement with experimental results.

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