This research is to develop and experiment the hybrid solar dryer by using cultivated banana as the ingredient in the experiment. The objective is to design create and test the hybrid solar dryer that using heat energy with infrared heater. The result from the experiment of drying cultivated banana at night-time by using heat energy from infrared heater is found that at night-time experiment cultivated bananas moisture is decrease more than at day-times experiment for 61.25 %. The temperature inside the hybrid solar dryer at night when using heat energy from infrared heater is at 49.1-55.0°C. Using heat from sunlight together with infrared heater cause the cultivated bananas moisture to decrease better approximately 27 % when compare to drying with heat energy by only sunlight.

The purposes of this research were to develop and to test performance of mini heat pump dryer for slice banana. Drying chamber of 0.48×0.47×0.39 m3 was designed and it could contain three trays. The three trays had dimension of 0.33×0.409 m2. A blower with 174.6 W motor of air condition was modify and could adjust flow rates of three levels for air cycle system in dryer. The air system had bypass air at evaporator. The refrigerant of R-134a and four main parts were used in the heat pump system. The four main parts were a 497 W hermetic compressor a 1800 W condenser an expansion valve and a 1300 W evaporator. Experiments for test performance of the mini heat pump dryer used close loop air system an evaporator bypass air of 60 % a temperature of 60 oC and various flow rates of 0.117 0.128 and 0.140 m3/s. Slide bananas of 400-500 g had an initial moisture content of 244-281 %dry basis and were dried until final moisture content lower than 6.24±0.007 %dry basis. It was found that the flow rates of 0.117 0.128 and 0.140 m3/s had coefficients of performance (COPh) of 3.32±0.066 3.88±0.031 and 4.24±0.08 respectively and had specific moisture extraction rates (SMER) of 184.5±11.85 186.2±8.17 and 200.1±21.34 g/kWh respectively. The flow rate at 0.140 m3/s was the best condition because it had high specific moisture extraction rate.

The objective of this research was to study of rotary drying of high-moisture long pepper by using a combined hot air and infrared radiation. The experiment was carried out at the drying temperatures of 80 90 and 100 °C infrared power level of 500 W hot air velocity of 2.5 m/s and rotary revolution of 3 6 and 9 rpm. In this study two patterns were examined by the different drying conditions namely 1) hot air drying and 2) combined hot air and infrared radiation drying. The effects of above drying parameters on the change in moisture content of long pepper and specific energy consumption (SEC) of the drying system were investigated. The results showed that the combined hot air and infrared radiation drying was shorter drying time than hot air drying. The lowest total SEC during drying process of 26.77 MJ/kg water when the drying temperatures of 80 °C infrared power level of 500 W hot air velocity of 2.5 m/s and rotary revolution of 3 rpm were used.

This research is the study of microwave distribution in the drying chamber to develop the belt-conveyor microwave dryer. The dimensions of the drying chamber are 90 cm width 3 cm length and 30 cm height. Two 800 W magnetrons were installed at the top of the chamber. It was found that the uniform of microwave distribution was observed at the center area of drying chamber. The uniform microwave distribution in the drying chamber at 400 W is achieved. A microwave leakage from the prototype is within the microwave oven safety standard of the US Department of Health and Human Services. This study can be used as a guideline for an industrial design for belt-conveyor microwave dryer.

This research developed a new model to determine the moisture diffusion coefficient for the thin-layer paddy drying with the spouted free-fall bed dryer. The design and construction of the dryer was done to experiment with the drying kinetics. The experiment has studied under conditions of hot air temperature of 60-150 °C the initial paddy mass of 5 - 15 kg and hot air velocity of 19 m/s. The results showed that the higher hot air temperature and the lower initial paddy mass resulted in a significant reduction in drying time. The experimental results were used to calibrate 12 of the most popular thin-layer drying models to find a suitable one considering based on the root mean square error (RMSE) chi-squared value (χ2) and the correlation coefficient (r). It was found that the popular thin layer drying model was able to accurately predict the effect of the moisture ratio considering both the influence of hot air temperature and the initial paddy mass in linear models. The highest accuracy was RMSE = 0.0279 χ2 = 0.00084 and r = 0.9938. In addition the experimental results have been used to synthesize the new diffusion moisture coefficient which is a function of initial paddy mass temperature and drying time. This developed model was based on an exponential function with only 7 model constants. The simulated results observed that the new model achieved the average error only 1.8 percent compared with the best model that uses up to 24 model constants.