In this paper, a thermal resistance network analytical model is proposed to investigate the thermal resistance and pressure drop in serpentine channel heat sinks with 180 deg bends. The total thermal resistance is obtained using a thermal resistance network model based on the equivalent thermal circuit method. Pressure drop is derived considering straight channel and bend loss because the bends interrupt the hydrodynamic boundary periodically. Considering the effects of laminar flow development and redevelopment, the bend loss coefficient is obtained as a function of the Reynolds number, aspect ratios, widths of fins, and turn clearances, through a three-regime correlation. The model is then experimentally validated by measuring the temperature and pressure characteristics of heat sinks with different Reynolds numbers and different geometric parameters. Finally, the temperature-rise and pressure distribution of the thermal fluid with Reynolds numbers of 500, 1000, and 1500 are examined utilizing this model. [DOI: 10.1115/1.4027508]

Thermal Analysis and Experimental Validation of Laminar Heat Transfer and Pressure Drop in Serpentine Channel Heat Sinks for Electronic Cooling

Heat in Computers: Applied Heat Transfer in Information Technology

Degradation of Fan Performance in Cooling Electronics: Experimental Investigation and Evaluating Numerical Techniques

The efficient heat dissipation of electronic equipment is very important, its heat dissipation performance directly determines the life of the equipment itself. A hand-held electronic communications equipment, when used in surface temperature is exorbitant, need to heat dissipation equipment efficiently, to ensure that the use of comfort in the handheld. In accordance with this requirement, this article presents a flexible composite material based on nano-efficient cooling methods that can keep the layout, through the improvement of internal thermal path, it can achieve the effective heat dissipation. The network thermal resistance method is used to analyze the heat transfer in the equipment, and the thermal analysis of the local thermal resistance is carried out. At the same time, through the modeling of electronic equipment and the analysis of finite elements, the temperature drop of the equipment after improvement is accurately judged. Finally, the device experimental performance comparison before and after the optimization of the standby mode and working mode is verified. The results show that the optimized equipment heat source temperature can be reduced by up to 8.5°C, the surface temperature of the equipment can be reduced by about 5°C~7°C, and the final control equipment in the steady standby state of the temperature of about 39±0.5°C, to ensure the comfort of use, and also improved the service life of the equipment. The efficient thermal design of electronic equipment based on flexible nanocomposites can provide a convenient and reliable cooling solution for high-heat flow density devices.

Application analysis of efficient heat dissipation of electronic equipment based on flexible nanocomposites

The Japanese industry has developed power electronics for railway trains, and now works to extend its experience to automobiles. The former part of the paper outlines the thermal issues pertinent to automobile applications as compared to railway applications. The discussion is developed for IGBT power modules and batteries. The latter part of the paper reviews the tools of thermal design analysis. A challenge to thermal design analysts is how to devise appropriate models of complex structures and thermal environment inside vehicles.

Thermal management of electronic and electrical devices in automobile environment

The issue addressed in the present study is how to model wiring substrates to perform heat conduction analysis on moderate computational resource. Equivalent thermal conductivity is a convenient measure in thermal modeling. However, its notion needs re-examination where higher accuracy of heat conduction analysis is pursued. Proposed is a scheme where the indexed volumetric metal contents are used to estimate the equivalent conductivity of representative volume element (RVE). The index is designed to reflect the effect of metal pattern on heat flow through RVE. In order to illustrate the core concept we report the analysis performed on template models of high-density interconnect (HDI) substrates. The element of HDI contains copper in several forms; through-via, continuous plane, and cross wires. Five heat flow directions are assumed; two are linear and three are right-angled turn. From combinations of the metal pattern and the heat flow direction twenty five templates are created, then, they are subjected to detailed numerical analysis. The values of equivalent thermal conductivity derived from the numerical solutions reveal that the gross volumetric metal content is totally inadequate as a parameter of thermal characterization. The paper also outlines the overall organization of our analysis system which is being developed in an industry-academia cooperative effort under the auspices of JSME.Copyright © 2009 by ASME

Thermal Characterization of High-Density Interconnects in the Form of Equivalent Thermal Conductivity

This paper describes the effects of the enclosure and its inlet on the performance of axial air-cooling fans installed in electronic equipment. The performance of an air-cooling fan is defined by its P - Q (pressure difference — flow rate) curve. Recent studies have reported that the P - Q curve of cooling fans depends on their operating environment. P - Q curves are normally used to define the performance of fans in the computational fluid dynamics (CFD) codes. Therefore the change of the P - Q curve may cause inaccurate CFD analyses to be performed in the thermal design of electronic equipment, including cooling fans. In this study, we measured the performance of test fans in an enclosure and explored the effects of the inlet size and shape while varying the speed of revolution of the fan. In particular, the static pressure difference between the front and rear of fans installed in a test enclosure was investigated. Our experiments clarified the effect of the enclosure on fan performance. The level of decrease of the maximum flow rate was found to be determined by the size of the inlet area, and was independent of the shape of the inlet and the revolution speed of the fan.

Effects of Electronic Enclosure and Inlet Area on P - Q Curves of Installed Axial Cooling Fans

In recent years, thermal design of electrical equipment becomes importance and fast thermal design is required due to the fast development of electrical devices. We have proposed the flow and thermal resistance network analysis (coupled network analysis) as a fast thermal design method for electrical equipment. In this paper, we described analytical accuracy of the coupled network analysis of thin electronic equipment including the finned heat sink. We especially focused on the prediction of thermal performance on heatsink by using the coupled network analysis. For considering the accuracy of the coupled network analysis, we compared the results of the coupled network analysis with those of CFD analysis and the experiment. The results showed that the coupled network analysis can predict accurate thermal performance of heat sink and moreover accurate temperature distribution of electrical equipment.Copyright © 2010 by ASME

Resistance Network Analysis of Airflow and Heat Transfer in a Thin Electronic Equipment Enclosure With a Localized Finned Heat Sink

This study describes an operation pressure and supplies flow rate of an axial cooling fan installed in high-density packaging electronic equipment. Fan performance is generally defined by their P-Q curve, specifically, a relationship between fan pressure rise (ΔP) and flow rate (Q). A compact cooling fan often operates in a high-density mounting device, which may decrease the fan performance. In this study, we focus on an obstruction near a fan, which is electronic components such as PCBs, capacitors and heat sinks, as one of a factor which decreases fan performance. We installed a perforated plate which simulated the above components near a fan and measured the P-Q curve. To investigate a relationship between a fan performance decrease and an opening position near the fan, a part of the perforated plate was closed. Closed position was changed and explored an opening condition which caused the dominant fan performance decrease. From experiments, it was found that the fan performance was decreased when flow passage in front of a fan was blocked by an obstruction. Especially, when flow passage in front of a fan hub was blocked, a dominantly reduction of fan pressure was caused. An obstruction rear a fan has no effect on a fan performance curve itself. In addition, opening conditions in front of a fan tip had a little influence on a fan pressure characteristic when there was no obstruction in front of a hub.Copyright © 2011 by JSME

Study on P-Q Curves of Cooling Fans for Thermal Design of Electronic Equipment (Effects of Opening Position of Obstructions Near a Fan)

The high-density interconnection substrate invariably poses enormous difficulty to thermal design analysts due to complex metal layout patterns embedded in the dielectric matrix. A modeling method is proposed, which produces effective thermal conductivity values for elements of the substrate under a specified boundary condition.

Takashi Fukue

Papers

Thermal Characterization of High-Density Interconnects in the Form of Equivalent Thermal Conductivity

Effects of Electronic Enclosure and Inlet Area on P - Q Curves of Installed Axial Cooling Fans

Resistance Network Analysis of Airflow and Heat Transfer in a Thin Electronic Equipment Enclosure With a Localized Finned Heat Sink

Study on P-Q Curves of Cooling Fans for Thermal Design of Electronic Equipment (Effects of Opening Position of Obstructions Near a Fan)

Thermal characterization of high-density interconnects: A methodolgy tested on a model coupon