Transient simulation and multi-objective optimization of a VSD ground source heat pump in various usage

Abstract

Abstract The main purpose of this research is to optimize the life cycle cost (LCC) while minimizing the annual irreversibility of the system in three different modes of a vertical ground heat pump (water-to-water) including heating, cooling, and multi-usage. The multi-objective optimization of the LCC and exergy destruction was done by using the multi-objective particle swarm optimization (MOPSO) algorithms and also by considering all involving effective parameters such as the number of boreholes, depth of buried pipes in ground source heat exchanger (GSHX), fan coil setpoint temperature and surface area of condenser and evaporator. In order to reduce energy consumption and meet the building s heat requirement at any time, the compressor was simulated with variable speed drive (VSD) in transient operations. In this study, the investigated refrigerant was R134a, and the shell-and-tube type of heat exchanger was considered for the condenser and evaporator. The obtained results show that the use of the heat pump in single heating mode leads to lower exergy destruction and better performance of the system in terms of exergy efficiency. Also, the economic results indicate that the total initial costs for the multi-usage mode is 27% higher than the single heating mode while it is 8.5% higher than the single cooling mode. The average electricity cost per operation time in multi-usage is 15% higher than single heating and 3% lower than single cooling and equal to 0.139 $/hour.