Numerical study of combustion and heat transfer in a composite heat carrier generator

To investigate the operational problems of the composite heat carrier generator (CHCG) in actual industrial applications such as overheating and poor safety performance, an integrated analytical model was established. For this model, the commercial software Fluent was first applied to simulate the gas-liquid turbulent flow, diesel vaporization and combustion, and the mixing process between the flue gas and the preheated water. Taking the parameters obtained from the Fluent model as the boundary condition, an indirect contact heat transfer model considering the heat transfer between the hot flue gas and the cold water has been solved. Based on this model, the areas where the phenomena of overheating and high thermal stress are prone to occur have been determined, and the size of the water sleeve has been redesigned.

Investigation of Phase Change Material Integrated With High Thermal Conductive Carbon Foam Inside Heat Sinks for Thermal Management of Electronic Components

In recent years phase change materials (PCMs) have emerged as a promising material for various thermal management applications. However, the lower thermal conductivity of PCM is a major hindrance in its widespread use. In the present study, an experimental investigation is carried out using high thermal conductive carbon foam (CF) embedded with PCM inside heat sink for thermal management of electronic components. Various configurations of heat sinks such as unfinned heat sink without PCM, unfinned heat sink integrated with PCM, unfinned heat sink integrated with CF-PCM composite, two finned heat sink integrated with PCM, and two finned heat sink integrated with CF-PCM composite are investigated. The vacuum impregnation technique is employed to infiltrate the PCM inside the CF. Heat flux is varied in the range of 1.5 to 2.5 kW/m2. Temperature variation of the heat sink base is used to compare the performance of various heat sinks. Unfinned heat sink without and with PCM is used for baseline comparison. Enhancement ratios are presented for various set point temperatures (SPT) such as 65 and 75°C. The highest enhancement ratio of 4.98 is obtained for two fin CF-PCM composite heat sink.

A Study on the Joining Technology of Copper-Aluminium Composite Heat-Dissipating Components

Copper-aluminium composite heat dissipation components have both the high thermal conductivity of copper and the low density of aluminium. Copper and aluminium are dissimilar materials as they have significant differences in physical and chemical properties, and hence it is not easy to weld them together. In this paper, the joining of copper to aluminium is studied by using the ultrasonic brazing technique. The results show that the copper and aluminium can be connected by ultrasonic brazing, and it is found that the bonding of the copper side interface is the weak link of the entire joint, but the joint strength can still reach 95MPa.

The Thermal Diffusivity of Glass Sieves: I. Liquid Saturated Frits

The thermal diffusivity of evacuated and liquid-saturated borosilicate glass sieves (frits) of porosities between 20 % and 48 % is presented as measured at room temperature. The saturants cover a range in thermal diffusivity from 0.091 mm2·s−1 to 0.143 mm2·s−1. The runs were carried out using a transient hot bridge (THB) measuring instrument of an expanded uncertainty of 5 % to 10 %. The experimental results are successfully fitted to a novel transient parallel-serial (TPSC) conduction model for the time-dependent composite heat transfer in porous media. The TPSC-model is an extension of the steady-state parallel-serial conduction (PSC) model to predict the thermal conductivity. The TPSC model confirms the so-called thermal porosity of the frits under test, a term that has been introduced in a former report on the thermal conductivity of the matrices (Hammerschmidt and Abid, Int J Thermophys 42:40, 2021). The experimental findings on the conductive transport of heat by glass sieves and their accurate mathematical description in the framework of the PSC and TPSC models might effectively support improving the thermal management of electronic devices and lithium-ion batteries.