The purpose of this research is to develop a hot air dryer using waste heat from a200 liter kiln for drying bananas and to investigate its drying performance. The main parts of the dryer consist of the drying chamber that has dimensions 0.71x0.83x.091 m3 the air circulation system and a heat exchanger which receives waste heat from the exhaust tube and kiln surface. The dryer was developed by designing a drying chamber on the top of a 200 liter kiln to reduce heat lost in the structure and an exhaust gas heat exchanger was developed using groups of copper tubes for increasing then heat transferred to the air. The drying performances were analyzed by measuring specific drying rates and specific energy consumption. Experiments were performed under different temperatures of 60 70 and 80℃ And at a constant velocity of 1.8 ms-1. Eucalyptus was selected as the heat source. Thirty kg of peeled bananas were prepared at an initial moisture content of 241.19±31.50% dry basis and were dried until to final moisture content of 48.47±10.46% dry basis. All experiments were carried out in duplicate. For temperatures of 60 70 and 80 ℃ the ave age specific drying rates were 0.085±0.0004 0.114±0.0009 and 0.1277±0.010 kg water h-1kesolid-1 and the average specific energy consumptions were 1.42±0.055 1.21±0.355 and 1.04±0.074 MJ/kg water respectively. Some dried bananas had burned at a temperature of 80℃ so at temperature of 70 ℃ was the optimal condition in this experiment. This produced good color a high specific drying rate and low specific energy consumption.

The study on baked crispy okra sheets (Hit 9701 species) by using a hot air dryer. The objective of this study was to investigate the okra sheets formula and manufacturing procees by hot air dryers with 3 methods; pouring finely blended okra onto the inside tray pouring finely blended okra onto the outside tray and pouring finely blended okra into an aluminum block. It was found that pouring finely blended okra into an aluminum block resulted in the least crack in the dried sheet with the rectangular shape remaining intact. After the forming method is decided on a study was conducted on the temperature to bake okra at 3 levels namely 70 80 and 90 C.It was found that baking okra at 80 C for 4.5 hours was suitable the baking and crispy okra sheets ended up with the lightness(L*) of 49.75 the green (a*) was-2.53 and yellowness (b*) of 23.71. The moisture content was at 5.07 % water activity content was 0.27 The hardness was 5.01 N and the crispness was 4.67. The results of chemical analysis showed that the carbohydrate content was 76.34% crude fibers was 10.72% ash content was 8.24% moisture content was 4.24% and fat content was 0.46%. From the study on the bacteriological quality it was found that the crispy okra sheet products can be stored at room temperature for 28 days.