Performance of Garlic Drying by Solar Energy Combined with Producer Gas

Abstract

The main objective of this research is to study and to design a pilot scaled dryer using the combination of solar energy and producer gas for garlic drying. During sunshine, the solar energy is preferably used by passing air through a 2.5 m² solar collector which is located in the top of the dryer at 14” of the inclination, while during no sunshine, the producer gas which is generated from charcoal gasifier is preferably used. The main combustible gases in producer gas are CO, CH, and H,, the total heating value of producer gas is 3.98 MJ/m³.

The experiments were carried out by varying the conditions of garlic drying. The appropriate conditions of 30 kg of garlics drying from the initial moisture content of 67% (wb) to the final moisture content of 60% (wb) were studied. The drying period was divided into 2 cases; the first one,drying by using producer gas only and the second one drying by using the combination of the solar and producer gas energy. Jn the first case, it was found that the average drying temperature was 55.6 ^oC and the drying time was 14 hour. For the second case; the average drying temperature was 45.4 ^oC and the drying time was 15 h, while the drying air fow rate was 0.17 kg/s in the both cases. The study of energy consumption indicated that both cases consumed energy from producer gas more than 60%.The economic analysis for the second, the drying time is fixed at 60, 90 and 140 days/year, the costs of dried garlic are 21.3, 16.4 and 13.0 Baht/kg dried garlic respectively, and the drying costs for evaporation are 94.9, 73.1 and 58.2 Bahtikg H₂O evap. respectively. When the selling price is fixed at 60 Baht, the payback periods are 4, 3 and 2 years.

Keywords : Garlic drying, solar energy, producer gas, energy consumption