International Journal of Thermal Sciences 151 (2020) 106260 Available online 13 January 2020 1290-0729/© 2020 Elsevier Masson SAS. All rights reserved. Phase change heat transfer in a rectangular enclosure as a function of inclination and fn placement Dominic Groulx a, * , Pascal H. Biwole b, c , Maha Bhouri a a Department of Mechanical Engineering, Dalhousie University, PO Box 15000, Halifax, NS, B3H 4R2, Canada b Universit� e Clermont Auvergne, CNRS, SIGMA Clermont, Institut Pascal, F-63000, Clermont–Ferrand, France c MINES ParisTech, PSL Research University, PERSEE - Center for Processes, Renewable Energies and Energy Systems, CS 10207, 06 904, Sophia Antipolis, France A R T I C L E INFO Keywords: Phase change heat transfer Solar PV panel Finned enclosure Inclination Natural convection Numerical simulation ABSTRACT In this paper, melting of a phase change material (PCM) inside a rectangular enclosure, possibly fnned and inclined, is studied numerically. The application of this work is related to the temperature control of a fnned PV panel flled with PCM and installed at different tilt angles. The studied system is modeled as a 2D rectangular enclosure flled with PCM (RT25) and packed between two aluminum plates, where the front side is exposed to a constant heat fux of 1000 W/m 2 for 2 h. Four geometries were considered including a non-fnned PCM enclo- sure, a PCM enclosure with one centered full-width fn, one half-width fn attached to the front plate, and one half-width fn attached to the back plate. Results have shown that the most effcient thermal management of the PV-PCM panel is obtained when the PCM enclosure is equipped with a full-width fn simultaneously attached to the front and back plates. With such a PV panel design, the PCM melting is dominated by natural convection heat transfer from both sides of the PCM enclosure at an early stage, with added heat losses from the back plate to the external environment. Accordingly, low values of the front and back plates temperatures can be maintained during a stabilization time of 80 min as long as the tilt angle is varied from 0 � to 75 � from the vertical. The effcient temperature control resulting from the full-width fn geometry is mainly related to the high overall heat transfer coeffcient obtained during the whole melting process. 1. Introduction The electrical effciency of a solar photovoltaic (PV) device is closely related to its operating temperature. Depending upon the type of solar cell and the climatic conditions, 6–25% of the incident solar radiation is converted to electricity whereas the rest is transformed to heat, which can result in an excessive increase of the PV module temperature and a signifcant decrease of its effciency in the absence of an adequate cooling method [1]. In case of solar PV panels, a drop in the conversion rate of approximately 0.3–0.65%/K over a nominal cell operating tem- perature of 298.15 K has been reported in the literature [2,3]. Among the various developed solutions to improve the thermal management of solar PV panels, the integration of a phase change material (PCM) on the back of the device has been proven to be an effective method of passive temperature control [2]. During the sunshine hours, the temperature of the PV panel can be kept slightly above the melting temperature of the PCM as the excess heat is stored in the PCM undergoing melting in a nearly isothermal process. When the sun goes down and the PV panel temperature de- creases, PCM solidifcation takes place and the stored energy is released back into the environment. The reduction in the PV panel temperature depends on the amount of PCM used, its thermophysical properties as well as the design of the PCM flled cavity. In many studies [3–5], RT25, a commercial paraffn-based PCM was selected due to its low melting temperature barely exceeding the PV characterization temperature and its high latent heat of fusion. This PCM was then used to fll a rectangular cavity in contact with the rear surface of the PV panel. Huang et al. [4] were the frst to develop a fnite volume numerical model based on a full-sized PV-PCM panel geometry, and validated it successfully with realistic experimental conditions. A parametric study was conducted to assess the thermal performance of the PV panel for different geometric properties of the rectangular PCM enclosure in cases without and with fns and under different insolation ranging from 750 to 1000 W/m 2 . Results showed that although the use of PCM prevented the increase of the PV panel temperature for a certain interval of time, the thermal performance of the device was still limited by the low thermal conductivity of the PCM. A signifcant improvement of the thermal * Corresponding author. E-mail address: dominic.groulx@dal.ca (D. Groulx). Contents lists available at ScienceDirect International Journal of Thermal Sciences journal homepage: http://www.elsevier.com/locate/ijts https://doi.org/10.1016/j.ijthermalsci.2020.106260 Received 3 September 2019; Received in revised form 24 November 2019; Accepted 3 January 2020