Performance evaluation of a seasonal residential space heating system based on thermochemical energy storage

Highlights: • Open thermochemical reactors serving a detached room is numerically investigated. • A 3D model for flow and heat transfer is coupled with a model of the reactive bed. • Thermal comfort and comfortable breathing conditions are obtained simultaneously. • Closed-loop configuration results in an energy saving of 76.61% than the open-loop. • An annual heating cost of 0.44 USD. kWh⁻¹ is estimated for the system. Performance of a novel configuration of residential seasonal space heating system based on open thermochemical energy storage (TCES) is numerically investigated. The system comprises two open TCES reactors and a humidifier operating in a complete closed-loop or in partial recirculation to maintain a comfortable temperature in a detached room. A detailed three-dimensional model for flow and heat transfer in a detached room is coupled with a model of the reactive bed undergoing exothermic reaction. The thermal and breathing comfort requirements in the room are obtained simultaneously by operating the system on partially recirculated air. A comparative study of the closed-loop configuration with its open-loop counterpart for the detached room indicates a significant energy saving of 76.61% (92.90 W) for the former. A realistic case study is conducted by operating the system with 10% fresh air, subject to ambient conditions for a winter night in Pune, India. Numerical studies conducted for constant ambient conditions reveal improvement in the room's heat distribution with increased airflow rate. Employment of two TCES reactors instead of one reactor enhances the Coefficient of Performance (COP) by a factor of 1.39. Adiabatic humidification in the humidifier eliminates its external heat requirement with the increase in the blower power input. Investigation of different locations for the exhaust vent is carried out for minimum heat loss to the surroundings. The system's energy consumption reduces by 10.18% using a cross-flow air-to-air heat exchanger for pre-heating fresh air. An annual heating cost of 0.44 USD.kWh⁻¹ is estimated for the system.