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Design and fabrication of a hydroformed absorber for an evacuated flat plate solar collector

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journal contribution
posted on 16.07.2018, 12:35 by Roger Moss, Stan Shire, Paul Henshall, Philip EamesPhilip Eames, Farid Arya, Trevor Hyde
© 2018 The Authors The concept of an evacuated flat plate collector was proposed over 40 years ago but, despite its professed advantages, very few manufacturers have developed commercial versions. The absorber is a key component of a flat plate collector: in the context of an evacuated panel, absorber design poses a number of technical challenges. A flooded panel absorber has been designed for use in evacuated flat plate solar collectors. The aim was to obtain higher efficiency, in a low out-gassing material, than would be possible using a conventional serpentine tube design. Initial plans for a micro-channel plate were modified when optimisation analysis showed that a flooded panel could achieve as good performance with easier fabrication. The absorber plate is made from hydroformed stainless steel sheets welded together and features an array of through-holes for the glass-supporting pillars with the square panel subdivided into two rectangles connected in series for ease of fabrication and better flow distribution. The coolant flow was modelled in Star-CCM+. FEM simulations based on tensile test data informed the choice of sheet thickness and weld radius around the holes to withstand the 1 bar pressure differential. Hydroforming is an effective method for producing sheet metal components, e.g. plates for heat exchangers or solar absorbers. As a thermal engineering experimental technique, the tooling is significantly cheaper than press tools since the mould does not need a matching die. In a research context, the ability to form plates in-house and explore profile and tooling options at low cost is very useful and might find application in other fields such as experimental heat exchangers. A hydroforming facility was built using 85 mm thick steel sheet and a 25 MPa hydraulic pump. This proved highly effective at forming 0.7 mm stainless steel sheet. A total of eight absorbers were fabricated and successfully leak tested using helium. Two variants were made: one kind for use in enclosures with a metallic rear tray, the other for enclosures with glass on both sides. The collector efficiency factor is estimated to be 3% higher than for commercial tube-on-plate designs.

Funding

This work was funded by the the Engineering and Physical Sciences Research Council (EPSRC) as part of a collaborative programme between Warwick, Loughborough and Ulster universities, reference EP/K009915/1, EP/K010107/1 and EP/K009230/ 1

History

School

  • Mechanical, Electrical and Manufacturing Engineering

Published in

Applied Thermal Engineering

Volume

138

Pages

456 - 464

Citation

MOSS, R. ...et al., 2018. Design and fabrication of a hydroformed absorber for an evacuated flat plate solar collector. Applied Thermal Engineering, 138, pp. 456-464.

Publisher

© The Authors. Published by Elsevier

Version

VoR (Version of Record)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution 4.0 International (CC BY 4.0) licence. Full details of this licence are available at: http://creativecommons.org/licenses/ by/4.0/

Acceptance date

06/04/2018

Publication date

2018-04-13

Copyright date

2018

Notes

This is an Open Access Article. It is published by Elsevier under the Creative Commons Attribution 4.0 Unported Licence (CC BY). Full details of this licence are available at: http://creativecommons.org/licenses/by/4.0/

ISSN

1359-4311

Language

en