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Buildings consume around 32% of the produced energy, worldwide and around 19% of the greenhouse gas emissions are related to them. It makes the buildings one of the largest energy consumers and one of the major sources of greenhouse gases emission. HVAC systems are one of the largest consumers of energy in buildings. In hot arid climates, cooling systems used in buildings impose a large pressure on the power grid, which may lead into blackouts. In order to address this problem, several approaches have been examined. Thermal energy storage, in particular, latent heat storage using phase change materials (PCM) has been notably considered in construction applications because of high energy storage densities. In this paper, the effect of using PCMs on energy consumption and peak load demand of a sample building is studied. Besides, impacts of precooling as a peak load shifting strategy is also investigated in presence of PCMs on the energy consumption of the sample building. The study was carried out for the weather condition of Kerman, Iran and the simulation is performed by TRNSYS software. Three types of phase change materials were investigated for two different scenarios. The simulation was performed at two stages and two modes for each stage which each mode had its own set point temperature. The application of PCMs was considered at the first stage and precooling added to the simulation at the second stage. The results of the first stage showed that employing PCMs in the studied building reduces the cooling load up to 13%. With precooling, the cooling load reduction was up to 16%. At all stages peak loads decreased with maximum 14% at the first stage and 42.5% at the second stage. It has been showed that the solid–liquid phase change temperature of the PCMs close to the selected room temperature, have significant impact on the performance of PCMs for reducing the energy consumption of the sample building compared to the other thermal properties. Due to the low electricity prices in Iran, despite the high amounts in load reduction achieved by each strategy, the cost savings during hot months of the year was not significant. [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]

• The SSPCM was employed to prepare cement mortars for plastering masonry brick walls. • An experimental setup was utilized to perform thermal performance test on the wall specimens. • The wall specimens were under ambient temperature conditions of two different cities of Iran. • The physical and mechanical properties of SSPCM-incorporated mortars were measured and analyzed. • The developed SSPCM incorporated in plaster mortar provides thermal energy storage capability. Phase change materials (PCMs) have been widely proven to provide thermal energy storage (TES) capacity in building systems. However, some potential problems associated with the incorporation of PCMs in building materials may cause uncertainty about their real performance. Among such problems, the leakage possibility of PCMs in the molten state has been greatly addressed in the literature. In this regard, this study is aimed to evaluate the mechanical and thermal behavior of a shape-stabilized PCM (SSPCM) as a TES component in the conventional wall system of buildings in Iran. For this purpose, PEG 600 was shape-stabilized in the porous structure of the silica fume as the supporting material using the vacuum impregnation method. The SSPCM was further employed to prepare cement mortars for plastering masonry brick wall specimens. The mechanical experiments on the SSPCM-incorporated mortars indicated satisfactory results to be used as the finishing plaster for masonry walls. Moreover, a novel experimental setup was utilized to perform thermal performance test on the wall specimens plastered with SSPCM-incorporated mortar under ambient temperature conditions of two different cities. Accordingly, the developed SSPCM exhibited the promising potential to provide TES capacity in external masonry wall systems by reducing the peak temperature as well as mitigating indoor temperature fluctuations. [ABSTRACT FROM AUTHOR]

One of the most common issues associated with wind energy penetration as a viable resource is high instability under diverse amplitudes and frequencies. Compressed air storage systems (CAES) and thermal energy storages (TES) not only are promising alternative solution for renewable resources generally, but they are also used with the aim of peak shaving to provide cleaner and affordable power. Due to high storage density with low temperature gradient between storing and retrieving in comparison with sensible heat storage, phase change material (PCM) is selected considering their thermophysical properties. This work, presents a recovery approach by using PCM during 12 h' compression periods to retrieve it in 12 h' expansion as a case study in November for Baladeh (a city in north of Iran). It is worthy to mention that, in order to use PCM in multiple mentioned stages, auxiliary heaters facilitate system to provide constant heat load in each used stage. This concludes system to be more efficient, sustainable and can reduce irreversibilities. Temperature of PCMs and amount of heat stored and released versus time are modeled. A good agreement between PCM model and reported results of related articles was seen. Following to the energy and exergy balances calculation, round-trip efficiency (RTE) and total exergy efficiency of system, reach 70.83%, 80.71%. Exergy analysis showed that near 60% exergy destruction occurred in PCMs with major contribution of second ones in both charge and discharge times. Sensitivity analysis is also investigated assuming the effect of number of wind turbines which shows a reduction in RTE, steeper slope in increasing TES volume for PCM3 and amount of heat stored, by increasing them. Image 10372 • A hybrid renewable energy storage system using phase change materials is investigated. • Compressed air storage and thermal energy storage methods are integrated. • RTE and total exergy efficiency of the system, reach 70.83%, 80.71%. • A city in north of Iran is considered for design of wind farm integrated to the energy system. [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]