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Your search keyword '"Heat loop"' showing total 3 results
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3 results on '"Heat loop"'

1. Advanced loop heat pipe application for cooling high power LED lights

Author

Igors Ušakovs and Luka Ivanovskis

Subjects
Two-phase heat transfer, LED thermal management, Heat loop, Heat loop pipe, Loop heat pipe, Engineering (General). Civil engineering (General), TA1-2040
Abstract

The ever-increasing power density of electronic devices fosters development of cooling systems. Among them, two-phase heat transfer devices in general and Loop Heat Pipes (LHP) in particular offer advantages by being completely passive while being able to cope with high heat fluxes. However, LHP manufacturing and especially integration is complicated by the loop architecture, which is not found in conventional Heat Pipes (HP). In an attempt to fit LHP layout into HP-like housing, a novel Heat Loop Pipe (HLP) device was designed, manufactured and tested in application to cooling a portable high-power (80 W) LED luminaire with a focusing reflector. The HLP utilizes co-axial layout of vapor and liquid lines and an additional wick in the condenser. The butane-charged, 350 mm-long HLP showed unexpectedly high resistance in the adverse orientation (evaporator above the condenser), which was an order of magnitude higher than in reflux orientation (0.8 K/W vs. 0.03 K/W). A possible explanation of this behavior in terms of vapor superheating in the evaporator channels is given. Analysis of the test results with help of p-T diagram justifies this assumption. Finding the root cause for such behavior requires further study.

Published
2024
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2. The influence of turbulence models on the accuracy of CFD analysis of a reciprocating mechanism driven heat loop

Author

O.T. Popoola and Yiding Cao

Subjects
Fluid Flow and Transfer Processes, Turbulence, K-epsilon turbulence model, business.industry, Computer science, 020209 energy, Heat loop, Turbulence modeling, Thermodynamics, 02 engineering and technology, Mechanics, K-omega turbulence model, Computational fluid dynamics, Solver, 01 natural sciences, 010305 fluids & plasmas, 0103 physical sciences, Heat transfer, 0202 electrical engineering, electronic engineering, information engineering, Fluid dynamics, Reciprocating flow, business, Engineering (miscellaneous), Turbulence models
Abstract

A bellows-type Reciprocating-Mechanism Driven Heat Loops (RMDHL) is a novel heat transfer device that could attain a high heat transfer rate through a reciprocating flow of the working fluid inside the heat transfer device. Although the device has been tested and validated experimentally, analytical or numerical study has not been undertaken to understand its working mechanism and provide guidance for the device design. In an effort to improve earlier numerical models of the RMDHL, different turbulence models for the RMDHL design have been studied and compared with prior experimental results to select the most suitable turbulence modeling techniques. The governing equations have been numerically solved using a CFD solver. For the three-dimensional fluid flow, several turbulence models have been studied for the RMDHL, including Standard, RNG, and Realizable k-ɛ Models, Standard and SST k-ω Models, Transition k - k L -ω Model and the Transition SST Model. The results of the simulations have been analyzed and ranked using numerical model calibration template. It was found that the standard k-ω Models provided the least accurate results while the RNG-k-ɛ Model provided the most accurate predictions. It is expected that the results will help improve the accuracy of the work on the RMDHL modeling.

Published
2016
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3. Numerical, Analytical, and Experimental Studies of Reciprocating Mechanism Driven Heat Loops for High Heat Flux Cooling

Author

Popoola, Olubunmi Tolulope and Popoola, Olubunmi Tolulope

Abstract

The Reciprocating Mechanism Driven Heat Loop (RMDHL) is a novel heat transfer device that utilizes reciprocating flow, either single-phase or two-phase flow, to enhance the thermal management in high tech inventions. The device attains a high heat transfer rate through a reciprocating flow of the working fluid inside the heat transfer device. Although the concept of the device has been tested and validated experimentally, analytical or numerical studies have not been undertaken to understand its working mechanism and provide guidance for the device design. The objectives of this study are to understand the underlying physical mechanisms of heat transfer in internal reciprocating flow, formulate corresponding heat transfer correlations, conduct an experimental study for the heat transfer coefficient, and numerically model the single-phase and two-phase operations of the RMDHL to predict its performance under different working conditions. The two-phase flow boiling model was developed from the Rensselaer Polytechnic Institute (RPI) model, and a virtual loop written in C programming language was used to eliminate the need for fluid structure interaction (FSI) modelling. The accuracy of several turbulence formulations, including the Standard, RNG, and Realizable k-ɛ Models, Standard and SST k-ω Models, Transition k - - ω Model, and Transition SST Model, have been tested in conjunction with a CFD solver to select the most suitable turbulence modelling techniques. The numerical results obtained from the single-phase and two-phase models are compared with relevant experimental data with good agreement. Three-dimensional numerical results indicate that the RMDHL can meaningfully reduce the peak temperature of an electronic device and result in significantly more uniform temperature across the device. In addition to the numerical study, experimental studies in conjunction with analytical studies are undertaken. Experimental data and related heat transfer coefficient as well

Published
2017

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