Promoting green energy initiatives are vital in educational institutes to encounter the energy demand and providing a sustainable life. In the most part, solar and wind energy options are chosen as renewable energy projects to meet part of electricity demand. However, because of the intermittent nature of these sources, alternative technologies should be chosen to provide effective and sustainable solutions. Various energy resources need to be combined in order to provide effective and efficient power generation. The present paper therefore focuses on the feasibility study of integrated energy systems for the energy supply of the educational institution. The work examines the techno-economic performance of various grid-connected and stand-alone integrated energy systems for an educational institute for making a decision before implementing green energy technologies. First, the energy demand is estimated for the entire campus. Further, the potential of renewable energy resources is assessed using NASA and NREL. A detailed survey was carried out to select the components required to model the various integrated energy systems. The modelling, optimization and economic study are performed using HOMER Pro software. A comparative economic analysis is made among considered integrated systems using Net Present Cost (NPC), COE and pay-back period. The study divulges that the grid-connected hybrid system is the optimal one for meeting the power demand of the institute in a reliable manner.

In this work, composite adsorbent materials are prepared using metal halide salts and expanded natural graphite (ENG). Ammonia adsorption and desorption pressure concentration isotherms of composite adsorbents are experimentally measured. The van't Hoff plots are constructed to calculate the enthalpy of a reaction during adsorption and desorption. The average value of adsorption enthalpies (∆Had) for MnCl2 + ENG and CaCl2 + ENG are 55.821 and 33.434 kJ mol−1, respectively, and average values of desorption enthalpies (∆Hdes) are 73.817 and 73.016 kJ mol−1, respectively. Comparison of ammonia sorption properties of composites and their corresponding plain salts is done. Thermodynamic analysis of adsorption thermal energy storage (ATES) system) showed that maximum gravimetric energy storage density for MnCl2 + ENG based system is 1394.83 kJ kg−1 (158.85 kWh m−3) at energy storage and ambient temperatures of 172°C and 35°C, respectively. The same for CaCl2 + ENG based system is 1350.86 kJ kg−1 (165.85 kWh m−3) at storage and ambient temperatures of 92°C and 35°C, respectively. Volumetric energy storage density is higher for CaCl2 + ENG based ATES system since it has higher density. Thermodynamic performance of composite‐based systems is compared with plain salts (MnCl2‐CaCl2) based thermal energy storage system.

No abstract

Summary The requirement of simultaneous heating and cooling effects at different zones of a building demands for the development of an energy‐efficient air‐conditioning system for heating and cooling outputs. In order to fulfil this requirement, a novel multistage hydrogen‐alloy–based sorption heat pump (H‐A SHP) for space air‐conditioning is proposed in the present work. The proposed system produces multiple cooling and heating outputs at 20°C and 45°C, respectively, with single heat input at 160°C. A set of MmNi5, La0.8Ce0.2Ni5, MmNi4.4Al0.6, and LaNi4.6Al0.4 metal hydrides (MHs) is chosen to operate at the above‐mentioned temperature range with hydrogen as working fluid. The proposed system can completely eliminate the requirement of conventional compressor because it operates using waste heat, and useful outputs (cooling‐heating) result from reaction enthalpies (MH + H2 interaction). The thermodynamic and heat‐hydrogen transfer analyses of H‐A SHP are carried out through finite volume approach, in which heat and mass transfer equations are solved to foresee the variations in MH bed temperature, hydrogen concentration, and heat interactions during cycle operation as well as the amount of cooling and heating outputs delivered to the air‐conditioning space. The numerical code is validated with experimental pressure‐concentration isotherms (PCIs) measured through Sievert's apparatus. The maximum heat exchange during the cooling and heating processes, at a particular instant of time, is observed as 257.5 and 286.1 W with cooling temperature of 10°C and heating temperature of 53°C, respectively. The thermodynamic performance is estimated as 178.5 kJ of cooling effect, 265.5 kJ of upgraded heat with overall coefficient of performance (COP) of 6.8, and overall specific alloy output of 396.5 W/0.34 kg of alloy.

In the present work, composite material, Mg‐50 wt% LaNi5, is thermodynamically characterized for thermochemical energy storage application, and its mechanism of hydrogen absorption is studied by using Johnson‐Mehl‐Avrami (JMA) equation. Pressure concentration isotherms (PCI) of the composite during hydrogen absorption and desorption are measured at 250°C, 300°C, 350°C, and 375°C. The enthalpy of absorption and enthalpy of desorption are calculated as 62.082 and 66.009 kJ/mol H2. Absorption kinetics is measured at 250°C, 300°C, and 350°C with hydrogen supply pressures of 10, 20, and 30 bar. The activation energies are calculated at different supply pressures using Arrhenius equation. Based on activation energy, the rate‐limiting steps are identified. A thermochemical energy storage method is proposed based on equilibrium pressure‐temperature relation obtained during absorption and desorption. The amount of thermochemical energy stored and recovered per kg of the composite is calculated based on reaction enthalpies and hydrogen concentration. The maximum theoretical thermochemical energy stored and recovered at a temperature of 350°C is calculated as 1452.198 and 1365.804 kJ/kg respectively. The maximum theoretical energy storage efficiency is estimated as 0.94. Hence, the composite, Mg‐50 wt% LaNi5, can be used as thermochemical energy storage material in the temperature range of 250°C‐350°C with a thermochemical energy storage capacity of 0.403 kWh/kg composite.