ORIGINAL Experimental study of the performance of a novel latent heat charging unit on charging and discharging processes Hocine Guellil 1 & Abdel Illah Nabil Korti 1 & Said Abboudi 2 Received: 25 August 2017 /Accepted: 23 August 2018 # Springer-Verlag GmbH Germany, part of Springer Nature 2018 Abstract An experimental study is carried out to analyze the performance of a novel latent heat thermal energy storage (LHTES) unit on charging and discharging processes. A finned tube air heat exchanger is filled with phase change material PCM and enclosed in an insulated storage unit. The heart of our heat exchanger is made up from a U tubes filled with paraffin wax and interconnected by flat fins to increase the heat exchange surface. The effect of power supply, air mass flow rate and using the flat fins on the thermals behavior and effectiveness were studied. The experiments showed that the fins can accelerates the time of the start and the end of fusion by about 55 and 72%, respectively. The charging phase can be prolonged to 94% by increasing the power supply by 32%, which also allowed them to store and recover more than 5 times of thermal energy. The results show that for a fixed power, the reduction of the flow of 54% accelerates the charging phase, increase the maximum temperature up to 18.3% and extend the discharging phase. 1 Introduction The thermal energy storage TES plays a significant role in the rational use of energy because it allows a coupling between production and consumption for energy. In intermittent power generation applications, TES is used to hold the energy for use during the night or on cloudy days. Thus, thermal energy storage is needed to improve the efficiency of solar thermal energy applications and to eliminate the mismatch between energy supply and energy demand. However, the TES used in the solar installations must be enough fast in order to store the maximum of heat during a time as short as possible. Thermal charging technology based on the use of phase change materials (PCM) are of research interest since many decades [1]. It is due to the high density of energy charging during the phase change in a very narrow temperature range. The principal criteria for selecting a PCM for a particular application is its phase change temperature (melting point). Korti [2] presented numerical and experimental studies of unsteady natural convection during solidification of cylindrical pure zinc ingots. He notices that the natural convection retards the solidification of the ingots and influences the solidification front progression, so that the microstructural composition of metals. Darzi et al. [3] carried a numerical study to simulate and find out the optimum design for plate type storage filled with PCM which is used in night ventilation systems. They found that the full melting of PCM has a linear relation with the thickness of PCM for their configurations. The outlet temperature and cooling power do not depend on the thickness of PCM plates in the short usage of PCM, but increasing the Stefan number or mass flow rate is the only way to increase the cooling power in short time usage. Hosseini et al. [ 4] performed a combined experimental and numerical study to understand the role of buoyancy driven convection during constrained melting of phase change materials (PCMs) inside a shell and tube heat exchanger. They observed from experimental results that the melting front appeared at dif- ferent times at positions close to the heat transfer fluid (HTF) tube and progressing at different rates outwards towards the shell.The computational results show that increasing the inlet water tem- perature to 80 °C leads to decreasing the total melting time to 37%. Next, the same authors [5] showed experimentally that increasing the inlet HTF temperature from 70 °C to 75 and 80 °C, theoretical effectiveness in charging and discharging pro- cesses rises from 81.1 to 88.4% and from 79.7 to 81.4% respec- tively. Tiari et al. [6] investigated numerically the thermal char- acteristics of a finned heat pipe-assisted latent heat thermal ener- gy storage system (LHTES). They studied the effects of heat pipe spacing and fins lengths and numbers. The analysis showed that * Hocine Guellil guellil10@yahoo.fr 1 ETAP Laboratory, FT, Department of Mechanics, University of Tlemcen, BP 230, 13000 Tlemcen, Algeria 2 ICB UMR 6303, CNRS, Département COMM, Université de Bourgogne Franche-Comté, UTBM, F-90010 Belfort, France Heat and Mass Transfer https://doi.org/10.1007/s00231-018-2462-8