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The present paper introduces a novel latent heat storage system applicable to hot water systems equipped with a Phase Change Material (PCM) and a Novel set of Blossom-Shaped Fins (BSFs). The water supplied by the collector is injected into the heat exchanger as a Heat Transfer Fluid (HTF). The PCM is charged during the daytime and will be reused as a primary system to supply the building's heating load at nighttime. The system's performance is investigated for various geometrical parameters, including the fin-number, fin's degree of compactness, fin-height, and the combined-fin heights/pin. Moreover, thermodynamic optimization through exergy analysis is applied to give better insights into the system's performance and efficiency. Results imply that both the variations of the fin-number and the fin's degree of compactness improve the charging time by 17% and 2%, respectively. Moreover, the fin-number variations positively affect the exergy efficiency by 6%, while compactness of fins shows a converse behavior with an 8% reduction in the exergy efficiency. On the other hand, the fin height/pin parameter variations improve the melting performance by 15% while having fewer exergy efficiencies. In addition, reducing the fin-height parameter improves the exergy efficiency of the case with the least melting time by 25% while associated with the most prolonged melting duration. Hence, considering the different impacts of geometric parameters on the exergy efficiency and the storage time, one should pay attention to the designer's view and climate conditions to choose the suitable heat exchanger based on the desired application. If the storage time is limited, the combined fin height/pin is preferred. Otherwise, the fin-height might be a better candidate to achieve higher exergy efficiencies and system performance. [ABSTRACT FROM AUTHOR]

This study is aimed to investigate the melting of phase change material (PCM) in a horizontal double pipe heat exchanger. The area between the pipes is filled with RT50 as PCM and water is used as a heat transfer fluid (HTF) which flows through inner pipe. The downward movement of inner pipe, inlet temperature and mass flow rate of HTF are considered and compared with the base system. The results show that inner pipe downward movement increases the convection-dominant zone which reduces melting time considerably (up to 64%). Results also indicate that by increasing the HTF inlet temperature thermal potential of the system increases which accelerates the melting process. However increasing the mass flow rate of HTF does not have significant role in melting rate. [ABSTRACT FROM AUTHOR]

This paper presents an experimental numerical study on melting behavior of a phase change material in a shell and tube heat exchanger. Thus the effects of parameters including adding Nano-Enhanced Phase Change Material (NEPCM) and inclination angle are considered and investigated. Experimental studies are designed to characterize PCM/NEPCM properties. The details of the process progression are presented via temperature contours, streamlines and phase front displacement. Enthalpy porosity method is used for modeling of the phase change process in which pure conduction and natural convection are considered in the simulation. Results reveal that thermal conduction mechanism is dominated at initial and final steps of melting that slows down the process. As the process advances, the buoyancy effect becomes dominant in the melting process. By increasing mass fractions of nanoparticle, thermal conductivity coefficient increases that leads to faster melting rate at the bottom of the heat exchanger. Also results indicate that increasing inclination angle leads to faster pace of melting at higher attitudes that results in shorter total melting time. Contemporaneous adding nanoparticle and increasing inclination angle reveals that both natural convection and thermal conductivity improves that leads to better melting of NEPCM. [ABSTRACT FROM AUTHOR]

In the present study, numerical simulation of refrigeration cycle incorporated with a PCM heat exchanger is carried out. To this end, the refrigeration cycle without PCM has been simulated and then, the performance coefficients of the refrigerator in either with and without PCM are evaluated. The PCM heat exchanger is located in the refrigeration cycle, at a location after the condenser and before the expansion valve. The utilised PCM is N-Octadecane with fusion temperature of 27.5 °C. The simulation of heat exchanger is based on computational fluid dynamics (CFD) in which the flow inside the pipe is considered one-dimensional in the axial extension and PCM surrounding it, is considered two dimensional. Numerical simulation is carried out using MATLAB software. Simulation results show that utilizing PCM in refrigeration cycle of a refrigerator causes an improvement in the convection procedure and results a 9.58% increase in performance coefficient of refrigerator. [ABSTRACT FROM AUTHOR]

In this paper, melting of a phase change material (PCM) in a multi-tube heat exchanger (MTHX) is investigated. Water, as the heat transfer fluid (HTF), flows through the inner tube/tubes and the outer one while RT35 as the PCM fills the middle. The aim of this study is to investigate the effect of number of inner tubes as a geometrical parameter during charging process. Also consequences of increasing operational parameters including the HTF mass flow rate and inlet temperature are studied. In order to understand the effects of the proposed configurations, a comparison between double pipe and simple MTHX is carried out. Results show that as the inlet temperature increases melting process accelerates and complete melting time reduces, whereas, similar mass flow rate increase doesn't reduce the melting time to such an extent. By increasing the number of inner tubes from 1 to 4 in the shell side of the MTHX, melt region enlarges and its including vortices strengthens which leads to a dominated convective heat transfer and thus a higher melting rate. This increase in number of tubes leads to 29% reduction in melting time. [ABSTRACT FROM AUTHOR]