Performance assessment of ground source heat pump system integrated with micro gas turbine: Waste heat recovery

Highlights: • Thermal performance of the spiral GHEs are determined experimentally and computationally. • Micro gas turbine and GSHP systems are integrated. • Waste energy of micro gas turbine exhaust gasses is stored in ground through spiral GHEs. • Effects of different storage temperatures on HTR of spiral GHEs are investigated. • Permanence of stored energy in ground after "storage process" is explored. - Abstract: Ground source heat pump (GSHP) systems become widespread due to their high efficiency in supplying heating demands of the buildings. Therefore, amount of extracted heat from ground through ground heat exchangers (GHEs) becomes as an important issue. This study consists of two main subjects, first, thermal capacity of an available application area which contains nine numbers of spiral GHEs is investigated experimentally and computationally. Existed operating system contains a GSHP and the nine spiral GHEs. In the second stage of the study, new operational system which consists of a micro gas turbine, a GSHP, sixteen spiral GHEs used for storing heat in ground and nine spiral GHEs used for extracting heat from ground, is suggested. Nowadays, micro gas turbines become popular based on their attractive features. However, large amount of exhaust gasses energy is wasted into the environment. In the new system, this waste energy is stored in ground through sixteen spiral GHEs during warm climate and then recovered in cold climate for supplying heating demands of the building. In this research, storage process of environmental waste energy in ground through spiral GHEs is simulated by COMSOL and thermal capacity of the developed application area is analyzed. Results show that, amount of extracted heat from ground through nine spiral GHEs is considerably increased after storage process.