Thermal resistance

About: Thermal resistance is a research topic. Over the lifetime, 21470 publications have been published within this topic receiving 312639 citations. The topic is also known as: absolute thermal resistance.

High-performance heat sinking for VLSI

Abstract: The problem of achieving compact, high-performance forced liquid cooling of planar integrated circuits has been investigated. The convective heat-transfer coefficient h between the substrate and the coolant was found to be the primary impediment to achieving low thermal resistance. For laminar flow in confined channels, h scales inversely with channel width, making microscopic channels desirable. The coolant viscosity determines the minimum practical channel width. The use of high-aspect ratio channels to increase surface area will, to an extent, further reduce thermal resistance. Based on these considerations, a new, very compact, water-cooled integral heat sink for silicon integrated circuits has been designed and tested. At a power density of 790 W/cm2, a maximum substrate temperature rise of 71°C above the input water temperature was measured, in good agreement with theory. By allowing such high power densities, the heat sink may greatly enhance the feasibility of ultrahigh-speed VLSI circuits.

Flash Method of Determining Thermal Diffusivity, Heat Capacity, and Thermal Conductivity

Abstract: A flash method of measuring the thermal diffusivity, heat capacity, and thermal conductivity is described for the first time. A high‐intensity short‐duration light pulse is absorbed in the front surface of a thermally insulated specimen a few millimeters thick coated with camphor black, and the resulting temperature history of the rear surface is measured by a thermocouple and recorded with an oscilloscope and camera. The thermal diffusivity is determined by the shape of the temperature versus time curve at the rear surface, the heat capacity by the maximum temperature indicated by the thermocouple, and the thermal conductivity by the product of the heat capacity, thermal diffusivity, and the density. These three thermal properties are determined for copper, silver, iron, nickel, aluminum, tin, zinc, and some alloys at 22°C and 135°C and compared with previously reported values.

Effective thermal conductivity of particulate composites with interfacial thermal resistance

Abstract: A methodology is introduced for predicting the effective thermal conductivity of arbitrary particulate composites with interfacial thermal resistance in terms of an effective medium approach combined with the essential concept of Kapitza thermal contact resistance. Results of the present model are compared to existing models and available experimental results. The proposed approach rediscovers the existing theoretical results for simple limiting cases. The comparisons between the predicted and experimental results of particulate diamond reinforced ZnS matrix and cordierite matrix composites and the particulate SiC reinforced Al matrix composite show good agreement. Numerical calculations of these different sets of composites show very interesting predictions concerning the effects of the particle shape and size and the interfacial thermal resistance.

Experimental and numerical study of pressure drop and heat transfer in a single-phase micro-channel heat sink

Abstract: The pressure drop and heat transfer characteristics of a single-phase micro-channel heat sink were investigated both experimentally and numerically. The heat sink was fabricated from oxygen-free copper and fitted with a polycarbonate plastic cover plate. The heat sink consisted of an array of rectangular micro-channels 231 lm wide and 713 lm deep. Deionized water was employed as the cooling liquid and two heat flux levels, q 00 ¼ 100 W=cm 2 and q 00 ¼ 200 W=cm 2 , defined relative to the planform area of the heat sink, were tested. The Reynolds number ranged from 139 to 1672 for q 00 ¼ 100 W =cm 2 , and 385 to 1289 for q 00 ¼ 200 W =cm 2 . The three-dimensional heat transfer characteristics of the heat sink were analyzed numerically by solving the conjugate heat transfer problem involving simultaneous determination of the temperature field in both the solid and liquid regions. Also presented and discussed is a detailed description of the local and average heat transfer characteristics of the heat sink. The measured pressure drop and temperature distributions show good agreement with the corresponding numerical predictions. These findings demonstrate that the conventional Navier–Stokes and energy equations can adequately predict the fluid flow and heat transfer characteristics of micro-channel heat sinks. 2002 Elsevier Science Ltd. All rights reserved.