Songchai Wiriyaumpaiwong

SOYBEAN DRYING BY TWO-DIMENSIONAL SPOUTED BED

Abstract Urease activity, cracking, and breakage are important factors in considering the quality of raw soybean for feed meal industries. A two-dimensional spouted bed dryer was investigated to determine its capability for thermally inactivating the urease enzyme and maintaining its other qualities. The experimental results have shown that the drying kinetics of soybean in a two-dimensional spouted bed dryer are of the form described in the thin layer drying. The expression for the model parameter in Newtons law of cooling equation accounting for the moisture contents and inlet air temperatures was developed. The initial moisture content and inlet air temperature conditions cause cracks in the kernels. The strong collision between kernels and deflector because of high superficial velocity leads to high percentage of broken soybeans in the spout region. However, the velocity of 15.9 m/s can reduce the breakage below 5%. The inactivation of urease at low-to-moderate moisture content is suitably described by the first order kinetics. The modified Monod equation is applied when the moisture content is higher than 26% dry basis due to the inhibitory effect of water content on the inactivation rate. To complete urease inactivation and maintain protein quality, the temperatures of 150°C should be used.

Drying and Urease Inactivation Models of Soybean Using Two-dimensional Spouted Bed Technique

The most important factors for examining the quality of soybeans in the animal feed industry are moisture and urease inactivation. Mathematical models for soybean drying and urease inactivation using two-dimensional spouted bed are developed and validated with experimental data. The influences of initial moisture content, inlet air temperature, air recycle on the drying rate, urease inactivation, and energy consumption are also studied. The results revealed that the increase in initial moisture content slightly affected the drying rate and urease inactivation while the inlet air temperature caused a significant effect. To obtain a high drying rate and save energy consumption, the recycle air ratio should be kept in a range of 80–90%.

Adsorption Cooling System Using Metal-Impregnated Zeolite-4A

The adsorption cooling systems have been developed to replace vapor compression due to their benefits of being environmentally friendly and energy saving. We prepared zeolite-4A and experimental cooling performance test of zeolite-water adsorption system. The adsorption cooling test-rig includes adsorber, evaporator, and condenser which perform in vacuum atmosphere. The maximum and minimum water adsorption capacity of different zeolites and COP were used to assess the performance of the adsorption cooling system. We found that loading zeolite-4A with higher levels of silver and copper increased COP. The Cu6%/zeolite-4A had the highest COP at 0.56 while COP of zeolite-4A alone was 0.38. Calculating the acceleration rate of zeolite-4A when adding 6% of copper would accelerate the COP at 46%.

Biomass Fired Grate Boiler for Small Industrial Heating System

Agricultural residues have been more extensively used as alternative fuels for combustion system in boiler. This is because they are low cost and eco-friendly. Fired tube boiler with traveling grate combustor was developed and tested at steam pressure of 3 bar, in this study. Rice straw and bagasse were used as energy resources. The effects of fuel feed rate (12–17 kg/hr) and air to fuel ratio (4.6–8.0 kgair/kgfuel) on the steam production rate, combustor efficiency, heat exchanger efficiency, overall efficiency, and quantity of carbon monoxide emitted were experimentally investigated. At such ranges of fuel feed rate and air to fuel ratio, 15–20 kg/hr steam was produced with the combustor efficiency of 16.4–28.2, heat exchanger efficiency of 74.0–82.7, and overall efficiency of 14.7–22.4. An increase in fuel feed rate and air to fuel ratio resulted in the higher steam production rate, and efficiencies of combustor and heat exchanger. Overall efficiency, however, was not much affected by A/F ratio. Investigation on flue gas composition showed that contents of carbon monoxide decreased with increasing air to fuel ratio and decreasing fuel feed rate. Analysis of economic feasibility indicated that using rice straw and bagasse in place of diesel required the payback period of 1.87 and 1.89 years respectively. Rate of return for utilization of rice straw and bagasse were 57.3 and 57.5% respectively.

Factors Affecting Performance of Job’s Tears Shelling Unit

The objective of this research was to study the effects of types of drum, clearances (CR) and drum speeds on performance of job’s tears shelling unit. The types of drum were peg tooth and rasp bar with an open shelling drum. Clearances of 10, 15 and 20 mm were tested with the drum speeds of 350, 400, 450 and 500 rpm. The results found that the rasp bar drum with 10 mm of clearance and 400 rpm of drum speed were suitable condition for shelling with capacity of 12.98 kg/h and efficiency of 99.76 % which provided 71.65% of whole and small damage kernels (% FK + % KQ).

Notice of Retraction Increase in charcoal yields of fast-growing trees

Fast-growing trees are widely cultivated in the north-eastern of Thailand. The residues of them are plentifully. The aim of this research was the increase in yield of charcoal during cool down process under nitrogen atmosphere. Two kinds of wood residues, eucalyptus and bur-flower, were used for investigation. Charcoal production was carbonized in a high temperature resistant cement furnace. The procedure for converting wood to charcoal was the heating rate of 60 °C/min and holding at the temperature of 550-600°C for 90 minutes. All of air inlet and outlet were closed to stop combustion reaction and the nitrogen gas was then fed into the furnace at the absolute pressures of 200, and 300 kPa during cool down charcoal over night. Yield percentage, proximate components, and heating value of charcoals were compared to charcoals from normal cool down process without nitrogen and traditional method. The results showed that both eucalyptus and bur-flower charcoals under nitrogen atmosphere at the absolute pressure of 200 kPa got the highest yield percentage. Under nitrogen atmosphere at this pressure, bur-flower wood obtained the charcoal yield higher than that eucalyptus wood. While bur-flower charcoal cooled down with nitrogen at the absolute pressure of 300 kPa and without nitrogen gas yielded the lower than that eucalyptus charcoal. When compared with charcoal of traditional method, only charcoal from normal cool down process without nitrogen produced the lower yield. In addition, the production of charcoal without nitrogen and with different nitrogen pressure and traditional method did not significantly affect on fixed carbon, volatile matter, moisture, ash contents, and heating value.

Desorption Isotherms, Drying Characteristics and Qualities of Glace Tropical Fruits Undergoing Forced Convection Solar Drying

Solar energy, a form of sustainable energy, has a great potential for a wide variety of applications because it is abundant and accessible, especially for countries located in the tropical region. Drying process is one of the prominent techniques for utilization of solar energy. This research work proposes a forced convection solar drying of osmotically pretreated fruits viz. mango, guava, and pineapple. The fruit cubes with a dimension of 1cm x 1cm x 1cm were immersed in 35% w./w. sucrose solution prior to the drying process. Drying kinetics, color and hardness of the final products obtained from solar drying were investigated and compared with those obtained from open air-sun drying. Desorption isotherms of the osmosed fruits were also examined and five mathematical models were used to fit the desorption curves. Experimental results revealed that solar drying provided higher drying rate than natural sun drying. Color of glace fruit processed by solar drying was more intense, indicated by lower value of lightness and higher value of yellowness, than that processed by sun drying. Hardness of the products dehydrated by both drying methods, however, was not significantly different (p>0.05). Validation of the mathematical models developed showed that the GAB model was most effective for describing desorption isotherms of osmotically pretreated mango and pineapple whereas Peleg’s model was most effective for describing desorption isotherms of osmotically pretreated guava.