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Thermal performance of a novel helically coiled oscillating heat pipe (HCOHP) for isothermal adsorption: an experimental study

Yeboah, S.K.; Darkwa, Jo

Thermal performance of a novel helically coiled oscillating heat pipe (HCOHP) for isothermal adsorption: an experimental study Thumbnail


Authors

S.K. Yeboah

JO DARKWA Jo.Darkwa@nottingham.ac.uk
Professor of Energy Storage Technologies



Abstract

Helically Coiled Oscillating Heat Pipes (HCOHPs) have been designed and tested under laboratory conditions to investigate their potential to achieve isothermal adsorption when integrated with a cylindrical solid desiccant packed bed system. The HCOHPs fabricated out of copper, are essentially single turn closed loop oscillating heat pipes with their evaporator and condenser sections helically coiled. They were charged with ethanol, methanol and deionized water respectively at approximately 60% volume fill ratio and tested by slotting through their helically coiled evaporators an empty cylindrical copper vessel which allowed hot air to be blown through at various heat loads to ascertain their thermal performances.

The results showed there were critical heat fluxes which varied with heat input amount at the evaporator, beyond which dry-out commenced and thermal resistance increased. These heat fluxes were ≤70W≤70W for the ethanol HCOHP and ≤105W≤105W for both the methanol and deionized water HCOHPs. Performance instabilities owing to liquid phase of the working fluid transitioning in the drying-out stage was observed for the methanol HCOHP beyond 234W. The variation of the effective thermal conductivities at the evaporators were found to influence the thermal contact resistance experienced at the contact interface of integration and the maximum heat input amount at the evaporators. Optimum performance between the HCOHPs was observed with the deionized water type. Overall, the HCOHPs were capable of managing relatively large amounts of heat input due to their helically coiled sections creating comparatively larger evaporator sections holding relatively more working fluid than the conventional serpentine single turn closed loop OHP system of the same volume and fill ratio. Investigations involving the visualization of the internal flow dynamics is recommended for future studies.

Citation

Yeboah, S., & Darkwa, J. (2018). Thermal performance of a novel helically coiled oscillating heat pipe (HCOHP) for isothermal adsorption: an experimental study. International Journal of Thermal Sciences, 128, https://doi.org/10.1016/j.ijthermalsci.2018.02.014

Journal Article Type Article
Acceptance Date Feb 15, 2018
Online Publication Date Feb 26, 2018
Publication Date Jun 30, 2018
Deposit Date Feb 28, 2018
Publicly Available Date Mar 29, 2024
Journal International Journal of Thermal Sciences
Print ISSN 1290-0729
Electronic ISSN 1290-0729
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 128
DOI https://doi.org/10.1016/j.ijthermalsci.2018.02.014
Keywords Oscillating heat pipes (OHP); Heat transfer; Working fluids; Isothermalization; Thermal resistance; Thermal contact resistance; Dry-out
Public URL https://nottingham-repository.worktribe.com/output/944380
Publisher URL https://www.sciencedirect.com/science/article/pii/S1290072917309523

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