Sintered aluminium heat pipe (SAHP)

This work is the product of an ongoing PhD project in the School of the Built and Natural Environment of Northumbria University in collaboration with the University of Liverpool and Thermacore Europe Ltd. The achievements at the end of the first year are summarized. The main objective of the project is to develop an aluminum ammonia heat pipe with a sintered wick structure. Currently available ammonia heat pipes mainly use extruded axially grooved aluminum tubes as a capillary wick. There have been a few attempts of employing porous steel or nickel wicks in steel tubes with ammonia as the working fluid (Bai, Lin et al. 2009)although it is a common practice in loop heat pipes but there is no report of aluminum-ammonia heat pipes porous aluminium wick structures. The main barrier is the difficulty of sintering aluminum powders to manufacture porous wicks. So far during this project promising sintered aluminum heat pipe samples have been manufactured using the Selective Laser Melting (SLM) technique with various wick characteristics. This SLM method has proven to be capable of manufacturing very complicated wick structures with different thickness, porosity, permeability and pore sizes in different regions of a heat pipe. In addition the entire heat pipe including the end cap, outer tube wall, wick and the fill tube can be generated in a single process

Pool boiling on modified surfaces using R-123

This article has been made available through the Brunel Open Access Publishing Fund.Saturated pool boiling of R-123 was investigated for five horizontal copper surfaces modified by different treatments, namely, an emery-polished surface, a fine sandblasted surface, a rough sandblasted surface, an electron beam-enhanced surface, and a sintered surface. Each 40-mm-diameter heating surface formed the upper face of an oxygen-free copper block, electrically heated by embedded cartridge heaters. The experiments were performed from the natural convection regime through nucleate boiling up to the critical heat flux, with both increasing and decreasing heat flux, at 1.01 bar, and additionally at 2 bar and 4 bar for the emery-polished surface. Significant enhancement of heat transfer with increasing surface modification was demonstrated, particularly for the electron beam-enhanced and sintered surfaces. The emery-polished and sandblasted surface results are compared with nucleate boiling correlations and other published data. © 2014 Syed W. Ahmad, John S. Lewis, Ryan J. McGlen, and Tassos G. Karayiannis Published with license by Taylor & Francis

Experimental Analysis of a Novel Cooling Material for Large Format Automotive Lithium-Ion Cells

© 2019 MDPI AG. All rights reserved. Cooling the surface of large format batteries with solid conductive plates, or fins, has an inherent advantage of reducing the number of liquid seals relative to some mini-channel cold plate designs, as liquid is not passed through the numerous individual plates directly. This may reduce the overall pack leakage risk which is of utmost importance due to safety concerns associated with the possibility of a cell short circuit and thermal runaway event. However, fin cooling comes at a cost of an increased thermal resistance which can lead to higher cell temperatures and a poorer temperature uniformity under aggressive heat generation conditions. In this paper, a novel graphite-based fin material with an in-plane thermal conductivity 5 times greater than aluminium with the same weight is presented for advanced battery cooling. The thermal performance of the fin is benchmarked against conventional copper and aluminium fins in an experimental programme cycling real 53 Ah pouch cells. The results from the extensive experimental testing indicate that the new fin can reduce both the peak measured temperature and surface temperature gradient by up to 8 °C and 5 °C respectively, when compared to aluminium fins under an aggressive electric vehicle duty-cycle

Heat Pipes: Theory, Design and Applications

Heat Pipes: Theory, Design and Applications, Seventh Edition, takes a highly practical approach to the design and selection of heat pipes, making it an essential guide for practicing engineers and an ideal text for postgraduate students. The expanded author team consolidate and update the theoretical background included in previous editions, and include new sections on recent developments in manufacturing methods, wick design and additional applications. The book serves as an introduction to the theory, design and application of the range of passive, two-phase, heat-transfer devices known as heat pipes, serving as an essential reference for those seeking a sound understanding of the principles of heat pipe technology. It provides an introduction to the basic principles of operation and design data which would permit the reader to design and fabricate a basic heat pipe. It also provides details of the various more complex configurations and designs currently available to assist in selecting such devices.This new edition has been fully updated to reflect the latest research and technologies and includes four brand new chapters on various types of heat pipe, theoretical principles of heat transfer and fluid mechanics, additive manufacturing and heat pipe heat exchangers

A study into different cell-level cooling strategies for cylindrical lithium-ion cells in automotive applications

Previous research has identified that the ageing rate and performance of lithium-ion cells is negatively influenced by unfavourable cell thermal conditions, specifically, high ambient temperatures and large in-cell temperature gradients. In this paper, the effectiveness of different cell cooling strategies on reducing the in-cell temperature gradient within cylindrical cells is analysed through the development of a 2-D transient bulk layer thermal model displaying anisotropic thermal conductivity. The model is validated against experimental temperature measurements in which the peak error of the simulation was found to be 2% and 5% for the experimental test drive cycle and constant 1C discharge respectively. Results indicate that radial cooling with air or singular tab cooling with liquid may be inadequate in limiting cell temperature gradients to below 5 ℃ for HEV type 32113 cells when subject to 4 loops of the US06 drive cycle

A novel method for manufacturing sintered aluminium heat pipes (SAHP)

This work is the product of an ongoing research project in the Faculty of Engineering and Environment of Northumbria University in collaboration with University of Liverpool and Thermacore of Ashington. This paper is a summary of the achievements at the midterm of the project. The main objective of the project is to develop an aluminium/ammonia heat pipe with a sintered wick structure. Currently available ammonia heat pipes mainly use extruded grooved aluminium tubes. There have been a small number of attempts of employing sintered steel or nickel wicks in steel tubes with ammonia as the working fluid [2] and [4] but this is the first paper to report on aluminium heat pipes with ammonia and a sintered wick structure. The main barrier is the difficulty of sintering aluminium powders to make sintered wicks. So far during this project promising sintered aluminium heat pipe samples have been manufactured using the Selective laser melting (SLM) technique with various wick characteristics. This new method has proved to be capable of producing very complicated wick structures with different thickness, porosity, permeability and pore sizes in different regions of a heat pipe in addition to the solid (nonporous) walls while the entire heat pipe including the end cap, wall, wick and the fill tube can be produced in a single process