Figure 9 HSDVC in Mode 3
The simulation of the solid desiccant system in mode 3 and the air being cooled by the vapor compression air conditioning system is described in Figure 9. The hot-humid air at point 1 is dehumidified by a desiccant wheel and it becomes hot-dry air which is specified as point 2. Then hot-dry air is sensibly cooled by a non-woven fabric-type indirect heat exchanger. Then the air reaches point 3 and it is further dehumidified by a desiccant wheel. The air will become hot-dry air and it reaches point 4. From point 4, the air is cooled by a vapor compression air conditioning system to reach point 5. Point 5 is the comfort condition where the air is supplied to the cabin. Mode 3 is the supply of air being given at 22°C and 50% Relative Humidity to the cabin mentioned by point 5 in Figure 9. The operation of the hybrid cooling system in mode 3 involves the use of two desiccant wheels for dehumidification. Therefore, this can be called a Two-stage HSDVC.
The cooling capacity for the two-stage HSDVC is given by Equation 3
\({\text{Cooling}\ \text{capacity}}_{\ \text{two}\ \text{stage}\ \text{HSDVC}}=\dot{m_{a}}\ \times\ \left(h_{\text{amb}-4}-h_{\text{supply}-5}\right)\ \)(3)
Figure 10 reveals the original cooling capacities of the VCAS and the HSDVC in mode 3 at ambient humidity ratios of 21,22 and 28 gkg-1d.a. The hybrid cooling system gives average cooling capacities of 13 kW, 14.4 kW, and 16.6 kW respectively for the same ambient humidity ratios.
The hybrid cooling system gives a cooling capacity reduction of 7.3 kW, 7.6 kW, and 11.4 kW respectively for the same ambient humidity ratios in mode 3. The hybrid cooling system gives an essential reduction in the cooling capacity of the vapor compression air conditioning system for numerous hot-humid ambient conditions.