Experimental evaluation of a 3-D dynamic solar-thermal collector model under time-varying environmental conditions

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Title: Experimental evaluation of a 3-D dynamic solar-thermal collector model under time-varying environmental conditions
Authors: Guarracino, I
Freeman, J
Markides, CN
Item Type: Conference Paper
Abstract: Reliable dynamic models are required for the correct prediction of the performance of solar-thermal collectors under variable solar-irradiance conditions. In this paper we present a 3-dimensional (3-D) dynamic thermal model applied to three different collector geometries: a flat plate collector (FPC), an evacuated tube collector (ETC), and also a hybrid photovoltaic-thermal (PVT) collector. Results from the model are evaluated against real data from a series of dynamic and steady-state experiments performed in Limassol, Cyprus and London, UK. The 3-D model equations are summarised and the test apparatuses and procedures are described. In the transient response tests, the model is found to under-predict the time constant for the ETC and PVT collectors by 35-55%, while for the simpler FPC the time constant is under-predicted by 20-35%. The collector model is also implemented into a wider domestic hot-water system model that includes a hot-water storage tank, in order to assess performance predictions over a diurnal operating period on an intermittently cloudy day. The results are compared to a single-node quasi-steady state model that uses the collector steady-state efficiency coefficients and a single-node dynamic model that uses a lumped collector thermal capacity (determined using experimental and calculation-based methods in the European Standard for solar collector testing). The 3-D model is shown to provide promising results that are within the range predicted by the two single-node dynamic models. For the PVT collector simulated under intermittent conditions, the predicted net daily energy gain to the store is found to be within 2% of experimentally obtained results. By comparison, a quasi-steady state model based on the collector’s steady-state efficiency curve is found to over-predict the thermal energy gain to the store by 8% over the same operating period.
Issue Date: 19-Jun-2016
Date of Acceptance: 10-May-2016
URI: http://hdl.handle.net/10044/1/32643
Copyright Statement: © the authors
Sponsor/Funder: Engineering & Physical Science Research Council (EPSRC)
Engineering & Physical Science Research Council (EPSRC)
Engineering and Physical Sciences Research Council
Funder's Grant Number: EP/J006041/1
Conference Name: ECOS 2016, 29th International conference on Efficiency, Cost, Optimization, Simulation and Environmental impact of Energy Systems
Publication Status: Published
Start Date: 2016-06-19
Finish Date: 2016-06-23
Conference Place: Portoroz, Slovenia
Appears in Collections:Faculty of Engineering
Chemical Engineering

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