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Experimental investigation into the feasibility of using a variable conductance heat pipe for controlled heat release from a phase-change material thermal store

Lookup NU author(s): Dr Richard Law, Emeritus Dr David Reay, Dr Ahmad MustaffarORCiD, Ryan McGlen



This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND).


© 2018 Elsevier Ltd Traditional heat storage uses large water tanks, with wide operating temperature differentials that restrict their use with heat pumps and Stirling engine DCHP systems. In contrast, the system developed under the ‘THERMAC’ project uses phase change materials (PCMs) for thermal storage to reduce system size, with a self-regulating, variable conductance heat pipe (VCHP) to control heat output. The VCHP is a heat pipe whose condenser is linked to a reservoir of non-condensable gas – in this case argon. Small temperature gradients expand or contract the argon along the condenser, so that it acts as a thermal switch by controlling the active length of the condenser. The study was successful in its main objective of demonstrating the basic technical feasibility of (i) Erythritol PCM as a means of heat storage (ii) over-coming the PCM's low thermal conductivity by using fins on the VCHP, and, (iii) a VCHP as a means of controlling the thermal output of the PCM storage system, thereby increasing their overall efficiency. Recommendations are made for further development of the ‘THERMAC’ concept.

Publication metadata

Author(s): Law R, Reay DA, Mustaffar A, McGlen RJ, Underwood C, Ng B

Publication type: Article

Publication status: Published

Journal: Thermal Science and Engineering Progress

Year: 2018

Volume: 7

Pages: 125-130

Print publication date: 01/09/2018

Online publication date: 24/05/2018

Acceptance date: 23/05/2018

Date deposited: 20/07/2018

ISSN (print): 2451-9049

Publisher: Elsevier BV


DOI: 10.1016/j.tsep.2018.05.007


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The project was funded by Innovate-UK/EPSRC