Impingement air cooled plate fin heat sinks. Part II - Thermal resistance model

A computational study is conducted to explore thermal performances of natural convection hybrid fin heat sinks (HF HSs). The proposed HF HSs are a hollow hybrid fin heat sink (HHF HS) and a solid hybrid fin heat sink (SHF HS). Parametric effects such as a fin spacing, an internal channel diameter, a heat dissipation on the performance of HF HSs are investigated by CFD analysis. Study results show that the thermal resistance of the HS increases while the mass-multiplied thermal resistance of the HS decreases associated with the increase of the channel diameter. The results also shows the thermal resistance of the SHF HS is 13% smaller, and the mass-multiplied thermal resistance of the HHF HS is 32% smaller compared with the pin fin heat sink (PF HS). These interesting results are mainly due to integrated effects of the mass-reduction, the surface area enhancement, and the heat pumping via the internal channel. Such better performances of HF HSs show the feasibility of alternatives to the conventional PF HS especially for passive cooling of LED lighting modules.

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Thermal-wet model of knitted double jersey based on backpropagation algorithm of neural network

Journal of Engineered Fibers and Fabrics ◽

10.1177/1558925019900837 ◽

2020 ◽

Vol 15 ◽

pp. 155892501990083

Author(s):

Xintong Li ◽

Honglian Cong ◽

Zhe Gao ◽

Zhijia Dong

Keyword(s):

Neural Network ◽

Water Vapor ◽

Thermal Resistance ◽

Resistance Test ◽

Training Algorithm ◽

Backpropagation Algorithm ◽

Optimal Network ◽

Resistance Model ◽

Hidden Layer ◽

The Relationship

In this article, thermal resistance test and water vapor resistance test were experimented to obtain data of heat and humidity performance. Canonical correlation analysis was used on determining influence of basic fabric parameters on heat and humidity performance. Thermal resistance model and water vapor resistance model were established with a three-layered feedforward-type neural network. For the generalization of the network and the difficulty of determining the optimal network structure, trainbr was chosen as training algorithm to find the relationship between input factors and output data. After training and verification, the number of hidden layer neurons in the thermal resistance model was 12, and the error reached 10−3. In the water vapor resistance model, the number of hidden layer neurons was 10, and the error reached 10−3.

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Experimental Measurements of the Flow and Heat Transfer of a Square Jet Impinging on an Array of Square Pin Fins

Heat Transfer, Volume 7 ◽

10.1115/imece2002-39244 ◽

2002 ◽

Cited By ~ 3

Author(s):

Johnny S. Issa ◽

Alfonso Ortega

Keyword(s):

Heat Transfer ◽

Thermal Resistance ◽

Flow Behavior ◽

Jet Impingement ◽

Tip Clearance ◽

Heat Sinks ◽

Clearance Ratio ◽

Cross Sectional ◽

Pressure Loss Coefficient ◽

Air Jet

An experimental investigation was conducted to explore the flow behavior, pressure drop, and heat transfer due to free air jet impingement on square in-line pin fin heat sinks (PFHS) mounted on a plane horizontal surface. A parametrically consistent set of aluminum heat sinks with fixed base dimension of 25 × 25 mm was used, with pin heights varying between 12.5 mm and 22.5 mm, and fin thickness between 1.5 mm and 2.5 mm. A 6:1 contracting nozzle having a square outlet cross sectional area of 25 × 25 mm was used to blow air at ambient temperature on the top of the heat sinks with velocities varying from 2 to 20 m/s. The ratio of the gap between the jet exit and the pin tips to the pin height, the so-called tip clearance ratio, was varied from 0 (no tip clearance) to 1. The stagnation pressure recovered at the center of the heat sink was higher for tall pins than short pins. The pressure loss coefficient showed a little dependence on Re, increased with increasing pin density, and pin diameter, and decreased with increasing pin height and clearance ratio. The overall base-to-ambient thermal resistance decreased with increasing Re number, pin density and pin diameter. Surprisingly, the dependence of the thermal resistance on the pin height and clearance ratio was shown to be mild at low Re, and to vanish at high Re number.

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Influence of selected factors on parameters of a cooling system with a Peltier module and forced air flow

Microelectronics International ◽

10.1108/mi-07-2021-0058 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Krzysztof Posobkiewicz ◽

Krzysztof Górecki

Keyword(s):

Thermal Resistance ◽

Heat Sink ◽

Cooling System ◽

Heat Sinks ◽

Cooling Power ◽

Cooling Systems ◽

Content Type ◽

Peltier Module ◽

Peltier Modules ◽

Forced Air

Purpose The purpose of this study is to investigate the validation of the usefulness of cooling systems containing Peltier modules for cooling power devices based on measurements of the influence of selected factors on the value of thermal resistance of such a cooling system. Design/methodology/approach A cooling system containing a heat-sink, a Peltier module and a fan was built by the authors and the measurements of temperatures and thermal resistance in various supply conditions of the Peltier module and the fan were carried out and discussed. Findings Conclusions from the research carried out answer the question if the use of Peltier modules in active cooling systems provides any benefits comparing with cooling systems containing just passive heat-sinks or conventional active heat-sinks constructed of a heat-sink and a fan. Research limitations/implications The research carried out is the preliminary stage to asses if a compact thermal model of the investigated cooling system can be formulated. Originality/value In the paper, the original results of measurements and calculations of parameters of a cooling system containing a Peltier module and an active heat-sink are presented and discussed. An influence of power dissipated in the components of the cooling system on its efficiency is investigated.

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Experimental Investigation of Heat Transfer in Impingement Air Cooled Plate Fin Heat Sinks

Journal of Electronic Packaging ◽

10.1115/1.2351906 ◽

2005 ◽

Vol 128 (4) ◽

pp. 412-418 ◽

Cited By ~ 21

Author(s):

Zhipeng Duan ◽

Y. S. Muzychka

Keyword(s):

Heat Transfer ◽

Experimental Data ◽

Thermal Resistance ◽

Thermal Performance ◽

Heat Transfer Model ◽

Heat Sinks ◽

Transfer Model ◽

Transfer Coefficients ◽

Developing Flow ◽

Rectangular Channels

Impingement cooling of plate fin heat sinks is examined. Experimental measurements of thermal performance were performed with four heat sinks of various impingement inlet widths, fin spacings, fin heights, and airflow velocities. The percent uncertainty in the measured thermal resistance was a maximum of 2.6% in the validation tests. Using a simple thermal resistance model based on developing laminar flow in rectangular channels, the actual mean heat transfer coefficients are obtained in order to develop a simple heat transfer model for the impingement plate fin heat sink system. The experimental results are combined into a dimensionless correlation for channel average Nusselt number Nu∼f(L*,Pr). We use a dimensionless thermal developing flow length, L*=(L∕2)∕(DhRePr), as the independent parameter. Results show that Nu∼1∕L*, similar to developing flow in parallel channels. The heat transfer model covers the practical operating range of most heat sinks, 0.01<L*<0.18. The accuracy of the heat transfer model was found to be within 11% of the experimental data taken on four heat sinks and other experimental data from the published literature at channel Reynolds numbers less than 1200. The proposed heat transfer model may be used to predict the thermal performance of impingement air cooled plate fin heat sinks for design purposes.

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Understanding the Impact of Flow Bypass on the Thermal Performance of Air Cooled Heat Sinks

Volume 10: Micro- and Nano-Systems Engineering and Packaging ◽

10.1115/imece2014-37521 ◽

2014 ◽

Author(s):

Krishna Kota ◽

Mohamed M. Awad

Keyword(s):

Energy Conservation ◽

Thermal Resistance ◽

Thermal Performance ◽

Heat Sink ◽

Heat Sinks ◽

Laminar Regime ◽

Flow Energy ◽

Factor Α ◽

The Impact ◽

Fundamental Mass

In this effort, theoretical modeling was employed to understand the impact of flow bypass on the thermal performance of air cooled heat sinks. Fundamental mass and flow energy conservation equations across a longitudinal fin heat sink configuration and the bypass region were applied and a generic parameter, referred as the Flow Bypass Factor (α), was identified from the theoretical solution that mathematically captures the effect of flow bypass as a quantifiable parameter on the junction-to-ambient thermal resistance of the heat sink. From the results obtained, it was found that, at least in the laminar regime, the impact of flow bypass on performance can be neglected for cases when the bypass gap is typically less than 5% of the fin height, and is almost linear at high relative bypass gaps (i.e., usually for bypass gaps that are more than 10–15% of the fin height). It was also found that the heat sink thermal resistance is more sensitive to small bypass gaps and the effect of flow bypass decreases with increasing bypass gap.

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