Development of Resource Map with the Total Energy Consumption for Open-Loop Type Geothermal Heat Pump System

Abstract

The resource map of open-loop type of ground source heat pump (GSHP) system is developed based on the annual total energy consumption. The annual total energy consumption is estimated from groundwater temperature, level and heating / cooling demand patterns. The study area of the resource map is the Nobi Plain, central Japan. This plain includes some alluvial fans, where the underground temperature in aquifers is fluctuated with an annual cycle. This temperature change is reflected in the estimation of the total energy consumption. A heating / cooling experiment at a public hall in the area with the annual underground temperature change is performed to construct the calculation method of the total energy consumption of the open-loop system. The calculation method on coefficient of performance (COP) of the heat pump is constructed from the multiple regression analysis on the monitoring data of groundwater temperature and the ratio of the produced heat to the heating/cooling capacity of the heat pump. The calculation method of the energy consumption of the water pump is constructed from the combination of monitoring results and the characteristic charts of the water pump. The distribution of the estimated annual total energy consumption of the open-loop system in an office building shows that the total energy consumption is lower in the northwestern part of the study area. This results from the shallower water table and lower groundwater temperature, because the cooling demand is higher than the heating one in an office building of the study area. Some areas of the alluvial fan also exhibit the lower annual power consumption, because the phase difference of the annual underground temperature change is almost 6 months from the ambient temperature change due to a lateral groundwater flow.