## 5 Results and Discussions  
### Time of Day Analysis of Cooling and Heating Operations  
Figure 9 shows the operation results on 9 August, when the secondary load of the cooling operation is the largest. In the HEX2 heat storage tank side inlet/outlet temperature transition in Figure 9a, Case WTES-C1-7 can send cold water of about 7 \({}^{\circ}\)C to 9 \({}^{\circ}\)C from the heat storage tank. In Case ATES-C1-7, the pumping temperature of the heat storage well has risen since 13:00, and heat exchange has not been possible since 16:00. An aquifer thermal storage system draws in groundwater from the surroundings as it pumps water from the aquifer. Therefore, heat is diffused in the aquifer, and it is difficult to maintain the temperature of the aquifer. The aquifer heat storage system is not suitable for use in the same way as the water heat storage system. Looking at the amount of heat stored and \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Air Conditioning Operation** & **Case** & **Heat Storage System** & **Operation Control and Method** \\ \hline \multirow{7}{*}{Cooling operation} & Case WTES-C1-7 & WTES system operation & Cold water operation \\  & & & 7 \({}^{\circ}\)C heat storage operation \\ \cline{2-4}  & Case ATES-C1-7 & & Cold water operation \\  & & & 7 \({}^{\circ}\)C heat storage operation \\ \cline{2-4}  & Case ATES-C2-7 & ATES system operation & Pre-cooling operation \\  & & & 7 \({}^{\circ}\)C heat storage operation \\ \cline{2-4}  & Case ATES-C2-14 & & Pre-cooling operation \\  & & & 14 \({}^{\circ}\)C heat storage operation \\ \hline \multirow{7}{*}{Heating operation} & Case WTES-H1-45 & WTES system operation & Hot water operation \\  & & & 45 \({}^{\circ}\)C heat storage operation \\ \cline{2-4}  & Case ATES-H1-45 & & Hot water operation \\  & & & 45 \({}^{\circ}\)C heat storage operation \\ \cline{2-4}  & Case ATES-H2-30 & ATES system operation & Pre-heating operation \\  & & & 30 \({}^{\circ}\)C heat storage operation \\ \cline{2-4}  & Case ATES-H2-25 & & Pre-heating operation \\  & & & 25 \({}^{\circ}\)C heat storage operation \\ \hline \multirow{7}{*}{Initial storage tank temperature: 15 \({}^{\circ}\)C} & Heat storage operation time: 10 h & \multirow{7}{*}{\begin{tabular}{} \end{tabular} } \\  & Heat utilization operation time: 10 h & \multirow{7}{*}{\
\begin{tabular}{} \end{tabular} } \\  & Stop operation time: 4 h & \multirow{7}{*}{
\begin{tabular}{} \end{tabular} } \\  & Initial groundwater temperature: 19.1 \({}^{\circ}\)C & \\  & Initial storage tank temperature: 15 \({}^{\circ}\)C & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Cooling and heating operation case. dissipated in Figure 9b, it can be seen that Case ATES-C1-7 does not secure as much heat as Case WTES-C1-7 even though it stores more heat than Case WTES-C1-7. Case ATES-C2-7, which uses the heat of the aquifer heat storage system for pre-cooling operation, stores heat at 7 \({}^{\circ}\)C and supplies heat to the pre-cooling coil during heat utilization operation. In this case, the HEX2 heat storage tank side inlet temperature is about the same as Case ATES-C1-7, but the HEX2 heat storage tank side outlet temperature is kept high, and the inlet/outlet temperature difference can be secured. Looking at the amount of heat released in Figure 9b, the amount of heat released is about the same as Case WTES-C1-7. However, the amount of heat storage is larger than Case WTES-C1-7. Case ATES-C2-14 specializes in raising the temperature level for heat storage to 14 \({}^{\circ}\)C and supplying cold heat for pre-cooling. The HEX2 heat storage side inlet temperature is stable at 14 \({}^{\circ}\)C to 15 \({}^{\circ}\)C, and the temperature difference from the HEX2 heat storage side outlet temperature can be secured. The HEX2 heat storage side outlet temperature is about 20 \({}^{\circ}\)C, which is higher than the groundwater temperature of 19.1 \({}^{\circ}\)C originally in the aquifer. Therefore, the heat of groundwater can be used for air conditioning.