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.

Due to the systems of mechanical vapor compression have a high energy consumption for air-conditioned space. Therefore the system of evaporative cooling presents as a promising alternative option for the air-conditioning system. Moreover the pre-cooling system is normally used to reduce an intake ambient air temperature before the air-conditioning system. As mentioned above this research aims to investigate the effectiveness of evaporative cooling system by using a car radiator for air per-cooling. In this research the commercial car radiator was used for cooling inlet ambient air by cooling water. The evaporative cooling system consisted of evaporative cooling panel with a maximum water rate of 40 lite/minute and a maximum air rate of 5100 m3/hr. The results show that most suitable water flow rate of radiator is 10 lite/minute and this radiator can make the differences of air temperature of about 8.9oC. Moreover the results also show that the effectiveness of evaporative cooling system could reach about 73.31% with a maximum sensible heat of 8.43 kW.

This research aims to develop the cement board from vesicular basalt fragment which reinforced with steel wire mesh. The ratio of Portland cement type1: fine sand: vesicular basalt fragment: sodium silicate: tap water was equal to 1: 2: 4: 0.03: 0.55 by weight. The 5 sizes of steel wire mesh (steel wire no.25) were installed including: 3/8” 1/2” 5/8” 3/4” and 1”. The cement boards were produced by compression machine. The property tests of cement-bonded fiberboard followed the TIS. 878-1994 standard (cement bonded particle board: high density). From the results the 3/4 of steel wire mesh size was the most suitable size for reinforcing the cement board from vesicular basalt fragment. This developed cement boards was the construction materials which had the high bending strength good thermal insulation and moisture protection properties.

This research aims to develop the gypsum refractory board mixed with corn leaf coir. The 5 ratios of gypsum plaster: corn leaf coir: tap water: sodium silicate are equal to 1: 0: 1: 0.03 1: 0.100: 1: 0.03 1: 0.150: 1: 0.03 1: 0.200: 1: 0.03 1: 0.250: 1: 0.03 และ 1: 0.300: 1: 0.03 by weighted. The gypsum refractory boards were produce by casting in normal temperature (30 – 35 degree of Celsius). The properties testing of gypsum refractory board mixed with corn leaf coir followed the TIS 219-2009 standard (gypsum plasterboard) included: breaking load nail pull resistance deflection water absorption density and thermal conductivity coefficient. From the results 1: 150: 1: 0.03 is the most suitable ratio of gypsum refractory board mixed with corn leaf coir. This developed gypsum refractory boards can reduce the quantity of corn leaf waste and get the good thermal insulation gypsum refractory board products.

This research aims to develop the waste heat energy conversion device to generate electricity through a thermoelectric generator (TEG) which is called “CHEU. This device is applied to the LPG cookstove that serves as a waste heat source. The thermoelectric generator with 4 modules in series connection is used to convert heat energy to electricity. The present research shows a modification of the CHEU based on two concepts as follows: (1) re-design the structure for heat transfer improvement and (2) select the high capability of TEG to support a high temperature from a heat source as a result of (1). In this study the modified CHEU is called “MCHEU”. A heat-load condition is set as the gas pressure of LPG which varies in a range of 0.1 - 0.6 kg/cm2 and the throttle valve is fixed approximately at 40% of a fully opened throttle while the air entrainment is fully opened throttle. Also the water-cooling system is used for heat dissipation. Base on the performance evaluation of MCHEU the interesting results are drawn as follows: 1) the maximum temperature difference is on an average value of 278.5oC at a maximum heat load condition while a maximum voltage current and power are on an average value of 18.83 V 5.67 A and 107 W respectively. 2) The temperature difference of MCHEU is higher than that of CHEU with an average value of 50%. 3) The output power obtained by MCHEU is higher than that of CHEU with an average value of 52% and takes less time about 40% for fully charging a battery (12V 7.5Ah). Nevertheless MCHEU usage does not affect the thermal efficiency of a cookstove. 4) The efficiency of an energy conversion obtained by MCHEU is 20% which is higher than that of CHEU about 2%.