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Summary: In the present experimental research, a five‐stage solar still was investigated using phase change material paraffin wax. Owing to Iran's climatic conditions and its location in a dry area and nonexistence of fresh water sources, producing this water from saline water sources is essential. In this research, thus, a multistage solar still was planned and examined as a commonly used freshwater source via (phase change material) paraffin wax. On the back of the collector absorber plate, paraffin wax (phase change material) was used as an additional energy source for the sun. The volume of water produced in different thicknesses of 2.5 cm, 5 cm, and without PCM was investigated. The study results specified that the application of phase change material paraffin wax in the thickness of 2.5 cm agent led to a 15% increase in freshwater production. The quantity of water generated in the flow rates of 0.7, 1.3, and 1.8 L/min was also studied. The highest quantity of water produced was obtained in the 1.3 L/min flow rate. Moreover, the quantity of water generated in the five stages of the desalination process was separately measured that the highest amount of production was associated with the first stage. [ABSTRACT FROM AUTHOR]

• The presence of PCMs reduces temperature fluctuations and heat transfer to the room. • Performing sensitivity analysis for HTR based on variation in properties. • Thermal conductivity of PCM plays most significant role in selecting the appropriate PCM. • For equal thermal conductivity, closer melting point to room temperature is preferred. • When PCM is closer to the exterior, a larger portion of it melts, HTR is greater. Passive latent heat thermal energy storage approach incorporating phase change materials (PCM) is a brilliant technique to tackle high energy consumption issue in buildings. This paper investigated the thermal performance of the conventional walls of buildings in Isfahan, Iran with the inclusion of thirteen different phase change materials. The studied base wall was composed of plaster (2 cm), clay brick (15 cm), and cement (3 cm). The effect of PCM position inside the wall on the heat transfer was assessed in two scenarios, namely: close to the interior and close to exterior. The nonlinear governing equations were solved using the finite volume method. The results show that the performance of PCM-based wall is strongly influenced by the thermal conductivity, phase-change enthalpy and melting temperature of PCM. A PCM can more efficiently reduce the heat transfer to the interior space in case it has a lower thermal conductivity, has a higher latent heat of phase-change, and its phase-change temperature is closer to the room temperature. Moreover, the thermal conductivity has priority over other PCM thermophysical properties. The lower PCM thermal conductivity leads to transfer the lower amount of heat to the interior space. A two-fold increase in the thickness of the PCM leads to less than a twofold reduction in the heat transfer. Among the studied PCMs, the heat transfer reduction by Enerciel 22 was within the range 15.6–47.6%, while this range was 2–7.8% for CaC l 2. 6 H 2 O. [ABSTRACT FROM AUTHOR]

• An integrated system is proposed to produce power, cooling, and freshwater. • Novel Thermal Energy Storage (TES) is suggested using phase change material (PCM). • Using high temperature PCM for TES, continuous operation of system is feasible. • The overall energy and exergy efficiencies are 40.52% and 14.40%, respectively. • The LCoE of the plant follows the downward trend of concentrated solar plants. In this article, three different modes of a novel integrated system would be evaluated by the application of high temperature Thermal Energy Storage (TES) to produce electricity, cooling, and freshwater. Freshwater is produced using the reverse osmosis (RO) desalination unit while Absorption Refrigeration Cycle (ARC) provides cooling. In this system, a high temperature Phase Change Material (PCM) is utilized to make the system working continuously even at nights. The output heat of gas turbine (GT) is also recovered utilizing the Organic Rankine Cycle (ORC). According to exergoeconomic analysis, the efficiencies, exergy destructions and product cost rates are computed. The multi-objective optimization has also been performed considering six different ORC working fluids and the changes in the direct normal irradiation of a city in Iran. In the trigeneration condition, the optimum values of the GT's compressor pressure ratio and ORC's turbine inlet pressure were obtained 9.06 and 3300 kPa, respectively. The exergy efficiency of the suggested system at the optimal condition is computed to be 14.40%, while that of energy is 40.52% with the total product cost rate of 30.524 $/GJ. The produced cooling capacity of the absorption system is also 1.62 MW whereas the output amount of freshwater and electricity for the users are about 5209.5 m3/day and 2.42 MW, respectively. The Levelized Cost of Electricity (LCoE) is also calculated to be 0.2341 $/kWh, which shows promising economic performance. [ABSTRACT FROM AUTHOR]