Thermodynamic and heat‐hydrogen transfer analyses of novel multistage hydrogen‐alloy sorption heat pump

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.

Performance investigation of multi-stage hydrogen-based sorption heat pump

“…Because of this, the present study aims to investigate the performance of a multi-stage sorption heat pump for airconditioning applications. In our previous study [10], we have proposed the concept of multi-stage sorption heat pump and investigated its thermodynamic and heat-mass transfer studies using the set of Ti 0.98 Zr 0.02 V 0.43 Fe 0.09 Cr 0.05 Mn 1.5 , MmNi 4.7 Al 0.3 , LaNi 4.8 Al 0.2 and Zr 0.9 Ti 0.1 Cr 0.9 Fe 1.1 metal hydrides. In the present study, the proposed thermodynamic system is adopted to investigate its performance by employing the metal hydrides chosen from literature as best suited pair, based on selection criteria for a given temperature range.…”

BIM Building HVAC Energy Saving Technology Based on Fractional Differential Equation

“…The cumulative duration that the indoor temperature is lower than the user's temperature requirement is used to reflect the influence of the control strategy on the user's thermal comfort [8]. In addition, because the user's acceptance range for room temperature is roughly ±2°C based on the temperature setting, the situation where the room temperature is lower than the original temperature setting by 2°C is regarded as a temperature violation.…”