For the second part, a set of the desiccant trays is assumed to integrated in a bed-type longan dryer. The computer program is constructed for calculating the energy saving of the interested system. Firstly, the air flow through the desiccant unit is assumed uniform flow pattern. In case of using multi-trays, the air stream acting with each tray is assumed to have equal mass flow rate, temperature and humidity. Moreover, the inlet temperature of the longan dryer is kept constant at 80 ºC with 60 hrs operating time for each drying batch. Figure 3 shows the schematic sketch of the longan dryer having desiccant unit. From this figure, the ambient air is flowed through the desiccant unit via the burner air fan. When the air passes the desiccant unit, the moisture is absorbed by the desiccant. The temperature of the leaving air is higher than that of the entering air as a result of the exothermic reaction during the adsorption process. After that the air flows into the combustion chamber and the air temperature is raised up to 80 ºC. The hot and dry air then flows into the dryer and releases the heat to longan. The flue gas leaves the dryer at the upper part of the longan bed.