Abstract
This research was to study the development of sliced pineapples dryer using heat pump. The objectives were designed, construction the prototype including testing the performance of a heat pump dryer. The pineapple used in this experiment is a species of “Pattavia pineapple” which has a natural pineapple flavor. They are sliced into circular shapes, like the frames of eyeglasses, with an approximate diameter of 10 cm and a thickness of about 1cm. Each slice weighs approximately 40 g. it was placed 5 shelves, each shelf weigh 2 kg., the total was 10 kg. The heat pump dryer was width 1.2 m long, 2.2 m high, and 1.5 m done. Steel frame wrapped in stainless steel 1 mm thick and 2.54 cm thick fiberglass exterior clad with galvanized sheets used. Using heat pumps 1 ton of cooling refrigerant is R-22 using the solenoid valve at the flow rate of the refrigerant entering the condenser outside. For cooling by excess temperature before drying. 0.5 HP motor drives the fan blowing through the coil. Tests dried pineapples on the drying temperature 45C. The initial moisture content of pineapples was 74.68% wet basis, final moisture content of products was 27. 66% wet basis. These processes spend 13 hours of drying time. The average drying rate (DRaverage) was 0.85 kgwater/h. The average moisture extraction rate (MERaverage) was 0.05 kgwater/h. The average specific moisture extraction rate (SMERaverage) was 0.022 kgwater/kW-h and the average performance of heat pump (COPhp,average) was 3.32. Analysis economics of using heat pump. The heat pumps dryer was cost 69,860 baht. The cost of drying sliced pineapples 321.75 baht / kg., with a payback period of 1.32 years, internal rate of return (IRR) 108.04%
Key words: pineapple slices, drying, heat pump