## 2 CCHP System
### Hybrid Desiccant Cooling System  
Figure 2a,b show a schematic and the psychrometric processes of the HDCS, respectively; 70% of the return air from the conditioned spaces (state 1) and 30% ambient air (state 6) are mixed to produce process air (state 2). The regeneration air of the desiccant rotor is heated by passing ambient air (state 6) through the condenser of the heat pump (state 7) and by the heat recovered from the CHP system (state 8) and supplied to the regeneration channel of the desiccant rotor. When the process air passes through the dehumidification channel of the desiccant rotor, the humidity decreases because of the desiccant, and the temperature increases because of the regeneration heat (processes 2 and 31). Subsequently, the regeneration air is supplied to the desiccant rotor, and the moisture absorbed by the desiccant is carried over and removed (processes 8 and 9). The desiccant rotor is made of a polymeric desiccant named super desiccant polymer (SDP), whose sorption capacity is two to three times greater than that of silica gel [19]. The hot dry process air passing through the desiccant rotor is sensibly cooled as it passes through the dry channel of the regenerative evaporative cooler (REC) (processes 3 and 4). At this time, 30% of the process air is injected into the wet channel of the REC to achieve evaporative cooling. Owing to South Korea's humid outdoor air conditions in summer, the combination of sensible heat cooling and evaporative cooling is insufficient. Therefore, in the HDCS, the process air was additionally cooled when it passed through the evaporator of the heat pump (processes 4 and 5).  
The specifications of the hybrid desiccant cooler are presented in Table 2. The cooling capacity of the HDCS was 9 kW and the power of the compressor driving the heat pump was 0.9 kW. The power of the process fan and return fan was 0.7 and 0.25 kW, respectively, and these values were comparable to the compressor power. The heat required to regenerate the desiccant was 6.94 kW under the design conditions.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{\begin{tabular}{c} **Capacity** \\ **(kW)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Compressor** \\ **Power** \\ **(kW)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Desiccant** \\ **Rotor** \\ **Power** \\ **(kW)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **PF** \\ **Power** \\ **(kW)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **RF** \\ **Power** \\ **(kW)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Rated** \\ **Reference** \\ **Heat(kW)** \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} \(\dot{\dot{\dot{\dot{\dot{\dot{\dot{\dot{\dot{\dot{\dot{\dot{\dot{ \dot{ \dot{ \dot{     }}}}}}}}}}}}}\)\(\mathbf{\dot{\dot{\dot{\dot{ \dot{\dot{\dot{\dot{\dot{\dot{\dot{\dot{\dot{\dot{\dot{\dot{\dot{ }}}}}}}}}}}}}}}\)** \\ **(m\({}^{3}\)/min)** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **Hot-Water** \\ **Flow Rate** \\ **(L/min)** \\ \end{tabular} } \\ \hline
9 & 0.9 & 0.015 & 0.7 & 0.25 & 6.94 & 23.9 & 20.5 & 8 \\ \hline \hline \end{tabular} \end{table  Table 2: Specifications of HDCS.  
Figure 2: (a) Schematic diagram and (b) psychometric process of an HDCS.