Heat transfer analysis of phase change process in a finned-tube thermal energy storage system using artificial neural network Kemal Ermis a,c,1 , Aytunc Erek b , Ibrahim Dincer c, * a Department of Mechanical Education, Sakarya University, Sakarya, 54187, Turkey b Department of Mechanical Engineering, Dokuz Eylul University, Bornova, 35100 Izmir, Turkey c Faculty of Engineering and Applied Science, University of Ontario Institute of Technology (UOIT), 2000 Simcoe Street North, Oshawa, Ont., Canada L1H 7K4 Received 15 April 2006 Available online 8 March 2007 Abstract In this study, a feed-forward back-propagation artificial neural network (ANN) algorithm is proposed for heat transfer analysis of phase change process in a finned-tube, latent heat thermal energy storage system. Heat storage through phase change material (PCM) around the finned tube is experimentally studied. A numerical study is performed to investigate the effect of fin and flow param- eter by the solving governing equations for the heat transfer fluid, pipe wall and phase change material. Learning process is applied to correlate the total heat stored in different fin types of tubes, various Reynolds numbers and different inlet temperatures. A number of hidden numbers of ANN are trained for the best output prediction of the heat storage. The predicted total heat storage values obtained by an ANN model with extensive sets of non-training experimental data are then compared with experimental measurements and numer- ical results. The trained ANN model with an absolute mean relative error of 5.58% shows good performance to predict the total amount of heat stored. The ANN results are found to be more accurate than the numerical model results. The present study using ANN approach for heat transfer analysis in phase change heat storage process appears to be significant for practical thermal energy storage applications. Ó 2007 Elsevier Ltd. All rights reserved. Keywords: Heat transfer rate; Finned tube; Thermal energy storage; Artificial neural networks; Numerical simulation; Phase change material 1. Introduction Thermal energy storage (TES) is considered to be one of the most important energy technologies, and recently, increasing attention has been paid to utilizing TES in a vari- ety of thermal engineering applications ranging from heat- ing to cooling (including air conditioning) processes [1]. TES systems are now popular in many countries, particu- larly in Canada, the United States, and Europe. Because these are the most efficient methods to avoid costly energy price and to reduce summer-time peak load electricity demand. The increased cooling demand results in peak elec- trical power demand during the hottest summer days. TES systems not only shift cooling energy to use at non-peak times, but also reduce energy consumption, depending on site-specific design, notably where chillers can be operated at full load during the night. Dincer and Rosen [2] explained energetic, environmental and economic aspects of thermal energy storage systems for cooling capacity and found some of the advantages of utilizing TES such as reduced energy cost, consumption, equipment size and pollutant emissions, also increased flexibility of operation, efficiency and effec- tiveness of equipment utilization (for details, see [3]). Many researchers have focused on storing energy through the phase-change material due to their relatively low volume requirement and narrow band of temperature variation. A few studies related to the heat transfer through 0017-9310/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.ijheatmasstransfer.2006.12.017 * Corresponding author. Tel.: +1 905 721 3111; fax: +1 905 721 3140. E-mail addresses: Kemal.Ermis@uoit.ca (K. Ermis), aytunc.erek@ deu.edu.tr (A. Erek), Ibrahim.Dincer@uoit.ca (I. Dincer). 1 Post Doctoral Fellow at UOIT. www.elsevier.com/locate/ijhmt International Journal of Heat and Mass Transfer 50 (2007) 3163–3175