An Improved Guarded-Cold-Plate Thermal-Conductivity Apparatus

2009 ◽  
pp. 74-74-21 ◽  
Keyword(s):  
Thermal Conductivity ◽  
Cold Plate

A Theoretical and Experimental Investigation of Unidirectional Freezing of Nanoparticle-Enhanced Phase Change Materials

2012 ◽  
Vol 134 (9) ◽  
Author(s):  
Liwu Fan ◽  
J. M. Khodadadi
Keyword(s):  
Thermal Conductivity ◽  
Experimental Investigation ◽  
Phase Change ◽  
Phase Change Materials ◽  
Solid Phase ◽  
Experimental Setup ◽  
Cold Plate ◽  
Numerical Predictions ◽  
Unidirectional Freezing ◽  
Measured Thermal Conductivity

Highly-conductive nanostructures may be dispersed into phase change materials (PCM) to improve their effective thermal conductivity, thus leading to colloidal systems that are referred to as nanostructure-enhanced PCM (NePCM). Results of a theoretical and experimental investigation on freezing of NePCM in comparison to the base PCM are presented. A one-dimensional Stefan model was developed to study the unidirectional freezing of NePCM in a finite slab. Only the thermal energy equation was considered and the presence of static dispersed nanoparticles was modeled using effective media relations. A combination of analytical and integral methods was used to solve this moving boundary problem. The elapsed time to form a given thickness of frozen layer was therefore predicted numerically. A cooled-from-bottom unidirectional freezing experimental setup was designed, constructed, and tested. Thermocouple readings were recorded at several equally spaced locations along the freezing direction in order to monitor the progress of the freezing front. As an example, cyclohexane (C6H12) and copper oxide (CuO) nanoparticles were chosen to prepare the NePCM samples. The effective thermophysical and transport properties of these samples for various particle loadings (0.5/3.8, 1/7.5, and 2/14.7 vol. %/wt. %) were determined using the mixture and Maxwell models. Due to utilization of the Maxwell model for thermal conductivity of both phases, the numerical predictions showed that the freezing time is shortened linearly with increasing particle loading, whereas nonmonotonic expediting was observed experimentally. The maximum expediting was found to be nearly 8.23% for the 0.5 vol. % sample. In the absence of a nanoparticle transport model, the mismatch of the cold plate boundary conditions, lack of accurate thermophysical properties, especially in the solid phase of NePCM samples and precipitation issues with 2 vol. % samples were addressed by improving the experimental setup. Through adopting a copper cold plate, utilizing measured thermal conductivity data for both phases and using 1, 2, and 4 wt. % samples, good agreement between the experimental and numerical results were realized. Specifically, adoption of measured thermal conductivity values for the solid phase in the Stefan model that were originally underestimated proved to be a major cause of harmony between the experiments and predictions.

scholarly journals Three-Dimensional Thermal Modeling of Internal Shorting Process in a 20Ah Lithium-Ion Polymer Battery

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 1013
Author(s):  
Yubai Li ◽  
Zhifu Zhou ◽  
Wei-Tao Wu
Keyword(s):  
Thermal Conductivity ◽  
Lithium Ion Battery ◽  
Thermal Modeling ◽  
Electrical Potential ◽  
Three Dimensional ◽  
Lithium Ion ◽  
Maximum Temperature ◽  
Cold Plate ◽  
Lithium Ion Polymer Battery ◽  
Polymer Battery

To better address the safety issues of a lithium-ion battery, understanding of its internal shorting process is necessary. In this study, three-dimensional (3D) thermal modeling of a 20 Ah lithium-ion polymer battery under an internal shorting process is performed. The electrochemical thermal coupling scheme is considered, and a multi-scale modeling approach is employed. An equivalent circuit model is used for characterizing the subscale electrochemical behaviors. Then, at the cell scale, the electrical potential field and thermal field are resolved. For modeling the internal shorting process, a block of an internal short is directly planted inside the lithium-ion battery. Insights of the temperature evolutions and 3D temperature distributions are drawn from the simulations. The effects of shorting resistance, through-plane thermal conductivity, and mini-channel cold-plate cooling are investigated with the simulations. A large amount of heat generation by a small shorting resistance and highly localized temperature rise are the fundamental thermal features associated with the internal shorting process. The through-plane thermal conductivity plays an important role in the maximum temperature evolutions inside the battery cell, while the external cooling condition has a relatively weak effect. But the cold plate cooling can benefit lithium-ion battery safety by limiting the high temperature area in the internal shorting process through heat spreading.

An Experimental Study on the Convective Heat Transfer Behaviour of Diamond Nanofluids in Electronic Cooling Applications

2018 ◽  
Author(s):  
Farzin Mashali ◽  
Ethan M. Languri ◽  
Jim Davidson ◽  
David Kerns ◽  
Fahad Alkhaldi
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Experimental Study ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Base Fluid ◽  
Convective Heat Transfer Coefficient ◽  
Cold Plate

This study presents the convective heat transfer coefficient of 0.05 wt.% diamond nanofluids containing functionalized nanodiamond dispersed in a base fluid deionized (DI) water flowing in a conduction cold plate under turbulent flow conditions, experimentally. The conduction cold plate was heated via six cartridge heaters with a constant heat transfer rate. The primary experimental study has been implemented to investigate the thermal conductivity of diamond nanofluids which showed a higher effective thermal conductivity than that of the base fluid. In addition, nanofluid was flowed in a closed system with heating at the heat exchanger and cooling via a cooling tank to keep the inlet temperature constant to explore the convection heat transfer properties of diamond nanofluids. Results indicate that the convective heat transfer coefficient and Nusselt number of diamond nanofluid are higher than that of the DI water in a same flow rate, and these properties increased with increase in Reynolds number.

Optimal Design of Coldplates for CPU Coolers

2007 ◽  
Author(s):  
C. N. Rasmussen ◽  
C. B. Terp
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Transfer Coefficient ◽  
Plate Thickness ◽  
Source Area ◽  
Cold Plate ◽  
Plate Material ◽  
Cfd Simulations ◽  
Total Thermal Resistance ◽  
Effective Heat Transfer Coefficient

We here present the results of an effort to determine the influence of the parameters affecting cold-plate performance and to minimize the total thermal resistance of a CPU cold-plate. An analysis based on analytical calculations and CFD simulations shows that spreading resistance is affected not only by the heat source area, cold-plate thickness and thermal conductivity of the cold-plate material, but also by the effective heat transfer coefficient of the interface between cold-plate and cooling liquid. Different options for optimizing heat transfer through the cold-plate are discussed.

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