Experimental Evaluation of a Paraffin as Phase Change Material for Thermal Energy Storage in Laboratory Equipment and in a Shell-and-Tube Heat exchanger  
[PERSON]  
1 GREA Innovacio Concurrent, Universitat de Lleida, Edifici CREA, Pere de Cabrera s/n, 25001 Lleida, Spain; [EMAIL_ADDRESS] ([PERSON]); [EMAIL_ADDRESS] ([PERSON]); [EMAIL_ADDRESS] ([PERSON]); [EMAIL_ADDRESS] ([PERSON].) 1 GREA Innovacio Concurrent, Universitat de Lleida, Edifici CREA, Pere de Cabrera s/n, 25001 Lleida, Spain; [EMAIL_ADDRESS] ([PERSON]); [EMAIL_ADDRESS] ([PERSON]); [EMAIL_ADDRESS] ([PERSON]); [EMAIL_ADDRESS] ([PERSON]); [EMAIL_ADDRESS] ([PERSON].) 1 GREA Innovacio Concurrent, Universitat de Lleida, Edifici CREA, Pere de Cabrera s/n, 25001 Lleida, Spain; [EMAIL_ADDRESS] ([PERSON]); [EMAIL_ADDRESS] ([PERSON]); [EMAIL_ADDRESS] ([PERSON]); [EMAIL_ADDRESS] ([PERSON]); [EMAIL_ADDRESS] (L.M. ); [EMAIL_ADDRESS] (C.B.) 1 GREA Innovacio Concurrent, Universitat de Lleida, Edifici CREA, Pere de Cabrera s/n, 25001 Lleida, Spain; [EMAIL_ADDRESS] ([PERSON]); [EMAIL_ADDRESS] ([PERSON]); lmiro@diei.udl. material, which can be either in liquid or solid state. In latent heat storage technologies, the thermal energy is stored when the TES material, also called phase change material (PCM), undergoes phase change processes. Finally, in thermochemical heat storage technologies, the energy is stored after a reversible chemical reaction between two substances. Latent heat TES has been deeply studied during the past decades and it has been found to be nowadays more attractive than sensible heat storage despite the fact that, in terms of cost, sensible TES materials are cheaper than PCM because of their high storage densities and narrower operating temperatures [2], and more attractive than thermochemical heat storage because of their maturity. One of the most studied PCMs is paraffin [3], which is an organic PCM consisting of a mixture of straight chain \(n\)-alkanes CH\({}_{3}\)-(CH\({}_{2}\))-CH\({}_{3}\). However, due to the high cost of manufacturing, only technical grade paraffins (mixtures of many hydrocarbons) are used for latent heat TES purposes [4]. Several studies have already reported and demonstrated the desirable properties of paraffins, which make this organic PCM suitable for TES [5]. From the thermal point of view, paraffins are known to have high thermal energy storage capacity, relatively constant melting temperatures close to the assumed phase change temperature, negligible subcooling and low vapor pressure in the melting process. Furthermore, paraffin is chemically inert and stable; it does not show phase segregation, it is non-corrosive to the container material, and it is commercially available. There are also some undesirable properties that limit the potential capabilities of this material. Such major drawbacks are: large volume changes during phase transition, compatibility problems with plastic containers, possibility of flammability, and low thermal conductivity. With some modifications in the wax and in the storage unit, all the undesirable effects mentioned before can be partially addressed and even eliminated [6]. Several experimental studies concerning the melting and solidification processes of different technical grade paraffin have been conducted, reporting their desirable properties. [PERSON] [7] analyzed the behavior of paraffin RT-30 in a 48 L shell-and-tube heat exchanger during both melting and solidification processes using water as heat transfer fluid (HTF) at a single constant mass flow rate, observing that phase change occurred non-isothermally but within the melting zone. In a similar shell-and-tube heat exchanger, but under different mass flow rates and inlet HTF (water) temperatures, [PERSON] and [PERSON] [8] studied the thermal behavior of a paraffin wax with a melting temperature of 60 \({}^{\circ}\)C, observing that inlet temperature had a higher effect on the heat fraction during the PCM melting than the mass flow rate.