Loughborough University
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Optimal passage size for solar collector microchannel and tube-on-plate absorbers

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posted on 2017-09-22, 10:14 authored by Roger Moss, Stan Shire, Paul Henshall, Philip EamesPhilip Eames, Farid Arya, Trevor Hyde
© 2017 The Authors Solar thermal collectors for buildings use a heat transfer fluid passing through heat exchange channels in the absorber. Flat plate absorbers may pass the fluid through a tube bonded to a thermally conducting plate or achieve lower thermal resistance and pressure drop by using a flooded panel or microchannel design. The pressure drop should be low to minimise power input to the circulating pump. A method is presented for choosing the optimum channel hydraulic diameter subject to geometric similarity and pumping power constraints; this is an important preliminary design choice for any solar collector designer. The choice of pumping power is also illustrated in terms of relative energy source costs. Both microchannel and serpentine tube systems have an optimum passage diameter, albeit for different reasons. Double-pass and flooded panel designs are considered as special microchannel cases. To maintain efficiency, the pumping power per unit area must rise as the passage length increases. Beyond the optimum pumping power the rise in operating cost outweighs the increase in collector efficiency.


The authors are grateful to the Engineering and Physical Sciences Research Council (EPSRC) for funding this work as part of a collaborative programme between Warwick, Loughborough and Ulster universities, reference P/K009915/1, EP/K010107/1 and EP/K009230/1.



  • Mechanical, Electrical and Manufacturing Engineering

Published in

Solar Energy




718 - 731


MOSS, R. ...et al., 2017. Optimal passage size for solar collector microchannel and tube-on-plate absorbers. Solar Energy, 153, pp. 718-731.


© The Authors. Published by Elsevier


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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/

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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/




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