This research article explores the behavior of a phase change material (PCM) when it undergoes interrupted melting and freezing, through experimental investigations using a heat flow meter apparatus. A fatty acid-based organic PCM, encapsulated within polyethylene and thin aluminum foil layers, was experimentally tested in this study. Experiments were designed to represent multiple interrupted phase change scenarios that could occur within PCMs applied in buildings. The experimental results were analyzed and compared with previously reported assumptions in numerical models dealing with PCM hysteresis and interrupted phase change processes. These comparisons indicated that the assumptions used in the different numerical models considered can capture the interrupted phase change phenomena with varying degrees of accuracy. The findings also highlighted the need for additional experimental research on different phase change processes that can occur in building applications of PCMs.
The solar photovoltaic (PV) system is emerging energetically in meeting the present energy demands. A rise in PV module temperature reduces the electrical efficiency, which fails to meet the expected energy demand. The main objective of this research was to study the nature of OM29, which is an organic phase change material (PCM) used for PV module cooling during the summer season. A heat transfer network was developed to minimize the experimental difficulties and represent the working model as an electrical resistance circuit. Most existing PV module temperature (TPV) reduction technology fails to achieve the effective heat transfer from the PV module to PCM because there is an intermediate layer between the PV module and PCM. In this proposed method, liquid PCM is filled directly on the back surface of the PV module to overcome the conduction barrier and PCM attains the thermal energy directly from the PV module. Further, the rear side of the PCM is enclosed by tin combined with aluminium to avoid any leakages during phase change. Experimental results show that the PV module temperature decreased by a maximum of 1.2 °C using OM29 until 08:30. However, after 09:00, the OM29 PCM was unable to lower the TPV because OM29 is not capable of maintaining the latent heat property for a longer time and total amount of the PCM experimented in this study was not sufficient to store the PV module generated thermal energy for an entire day. The inability of the presented PCM to lower the temperature of the PV panel was attributed to the lower melting point of OM29. PCM back sheet was incapable of dissipating the stored PCM’s thermal energy to the ambient, and this makes the experimented PCM unsuitable for the selected location during summer.
The application of phase change material slurry to the refrigeration and air conditioning system opens a new way for energy saving and reduction of the quantity of refrigerant in the system, because it can serve as both the energy storage and transportation media in the secondary loop which is responsible for distributing the cooling power. In the present study, the experimental investigations of the forced flow and heat transfer characteristics of Tetrabutylammonium Bromide (TBAB in abbreviation) clathrate hydrate slurry (CHS) in both the plate heat exchanger (PHE) and double-tube heat exchanger (DHE) are carried out. It is found out that the pressure drop in the PHE is about 5–50 kPa at the flow rate of 2–14 L/min and is about 2–30 kPa at the flow rate of 3–14 L/min, which is nearly 2 times of that of the chilled water. The overall heat transfer coefficient is in the range of 2500–5000 W/(m2K) for TBAB CHS in the PHE and is about 1500–3500 W/(m2K) in the DHE, which are both higher than that of TBAB aqueous solution flow because of the involvement of the phase change of TBAB CHS.