Investigation of the usage of geothermal sourced heat pump in district heating system and its thermodynamics analysis

The heat pumps are alternative heating system related with their higher efficiency. Although heat pumps are not very common in Turkey, the applications of soil and water sourced heat pumps have increased recently. In this study, the usage of geothermal sourced heat pumps was investigated in district heating system and optimized taking the different designs into account. In these designs, taking different refrigerant fluids and system parameters into consideration, the capacities, COPs and exergy efficiencies of evaporator, heat center, radiator and pumps were calculated by means of energy and exergy analysis. In the next part of this study; the cost analysis of geothermal sourced heat pump in district heating system were separately performed for each design. Assuming the economic life of the geothermal sourced heat pump in district heating systems as 20 years, the economics of the system was investigated by Net Present Value analysis (NPV). Finally, all economically evaluated designs were modelled using Artificial Neural Network (ANN). The ANN models of geothermal sourced heat pump in district heating system was formed by using feed-forward back propagation network type and Levenberg-Marquardt (LM), Pola-Ribiere Conjugate Gradient (CGP) and Scaled Conjugate Gradient (SCG) training algorithms in MATLAB. The obtained results of network outputs were statistically evaluated for each model and the optimal network was determined according to best results. In the next stage of this study, the geothermal sourced heat pump in district heating system was optimized by using the determined optimal network. If analytical results compared with those of ANN, it was determined to be statistically acceptable. Finally, the proposed system was compared with the current system with no heat pump and it was found that the proposed system has been economically feasible in comparison the present one.