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Medium temperature heat pipes – Applications, challenges and future direction

Lookup NU author(s): Dr Tom WernerORCiD, Professor Volker Pickert, Dr Rafal Wrobel, Dr Richard Law



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Heat pipes have played a large part in the thermal management market for the past five decades and havecontributed to the development and optimisation of countless components in a wide range of high-level appli­cations, most notably in the aerospace, electronics, automotive and power generation industries. These thermalmanagement systems span a wide range of temperatures, which in turn requires the heat pipe fluid and casingmaterial to be specially selected to meet the application requirements. Recently, there has been an increasingdemand for heat pipes which can operate in the 300–600 ◦C temperature range – a range which is still under­developed in the heat pipe marketplace due to the lack of conventional fluids which can adequately operate atthese temperatures. This range is referred to as the ‘medium’ or ‘intermediate’ temperature range. The analysisand exploration of novel fluids, which could potentially be used in this range, will cater for a huge marketpotential. Although there has been mild development in this temperature range with the aim of testing particularfluid/metal combinations which may be suitable, there appears to currently be a severe lack of continuity in thework with little progression towards a definitive solution and no central reference catalogue of successful andunsuccessful tests. Previous works on the topic tends to follow a ‘patchwork’ process, often with overlaps intesting and with a focus only on long-term compatibility tests with a limited analytical approach which often leadto incompatible results. This paper intends to summarise all major and stand out efforts in developing mediumtemperature heat pipes and highlight the most promising fluids and wall materials which have been tested todate. To summarise the content, this review will explore (a) current applications which could benefit from theuse of medium temperature heat pipes, (b) the work that has been done on investigating medium temperaturefluids, (c) highlight some of the principles behind heat pipe performance prediction, fluid analysis, fluid/metalcompatibility and fluid selection and (d) suggest the potential future direction of research in this area, partic­ularly focusing on the development of novel heat pipe fluids. Additionally, a standardised fluid assessmentframework is also proposed aiming to aid the identification and analysis of both existing and newly developedheat pipe fluids.

Publication metadata

Author(s): Werner TC, Yan Y, Karayiannis T, Pickert V, Wrobel R, Law R

Publication type: Article

Publication status: Published

Journal: Applied Thermal Engineering

Year: 2024

Volume: 236

Issue: Part A

Print publication date: 05/01/2024

Online publication date: 19/08/2023

Acceptance date: 14/08/2023

Date deposited: 11/09/2023

ISSN (print): 1359-4311

ISSN (electronic): 1873-5606

Publisher: Elsevier Ltd


DOI: 10.1016/j.applthermaleng.2023.121371


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Funder referenceFunder name
Boyd Technologies Ashington UK Ltd
EPSRC (project code 1790747)
European H2020-MSCA-RISE ThermaSMART project (project code 778104)