The objective of this work is to assess the potential of the atmospheric water harvesting (AWH) by direct cooling under the climate of Thailand. The assessment was considered from water scarcity, meteorological data and engineering analysis, including moisture harvesting index (MHI), water capability and energy cost. The meteorological data between 2012-2021 were used as primary data for engineering analysis. The results showed that Thailand has the potential to supply freshwater by using AWH with direct cooling. The average MHI of Thailand is 0.548 which is comparable with high potential of global assessment. 71 cities from 77 cities in Thailand have MHI over 0.50, which is the favorable condition for AWH by direct cooling. From the calculation under Thailand conditions, the water harvesting rates by direct cooling could be in the range of 0.97-1.30 L/h with energy costs as low as 0.047 USD/L for 71 cities in Thailand.
This study was aimed to compare the production time (germination and drying process) and quality of germinated brown rice (GBR) obtained from the water spraying-based GBR production (Sprayed-GBR) system and the water soaking-based GBR production (Soaked-GBR) system. The results showed that the Sprayed-GBR, in the germination process, required 2.5 h for spraying in a water spraying step to obtain paddy with the moisture content of 30% (w.b.) and 26 h in an incubation step to obtain the 90% germination percentage. This led to a shorter germination time compared to the Soaked-GBR, which required a germination time of 50 h for a 90% germination percentage. After germination, the moisture content of the Sprayed-GBR was lower than that of the Soaked-GBR. This provided a shorter drying time in the Sprayed-GBR (27 min) drying process compared with the Soaked-GBR (33 min). For GBR qualities, the Sprayed-GBR could decrease the unpleasant odor problem by providing a smaller number of attached microorganisms after germination (Shade drying), leading to a significantly higher score in the odor and the overall acceptability than the Soaked-GBR. This indicated that the Sprayed-GBR got more consumer acceptance. Moreover, the head rice yield value of the Sprayed-GBR was not different from that of the Soaked-GBR. However, the Sprayed-GBR provided a significantly lower GABA content and a significantly higher percentage of fissured kernels than the Soaked-GBR.
The objective of this research is to design and construct a hammer mill for grinding leonardite charcoal (Lignite, class J). The conditions for the design and construction of the grinder are hammer thickness, 3, 6, and 9 mm, a number, hammer 20, 24, and 28. The size of the ground leonardite should range between 250 mm to 30 mm (less than 0.066 mm). The hammer thickness and number of hammers were chosen alternatingly in order to see the effect of these two parameters. By manipulating these two parameters, it was found that the optimum operation can be achieved by using 28 hammers having a thickness of 3 mm. It results in the highest grinding efficiency of 96.2 percent. Percentages of the grate (retained) and passed of the ground mineral are found for each sieve size by means of weight. The approximations of the retained and passed were calculated and found to intersect at 225 mm. At the intersection, the percentage by weight passed through the sieve is 50 percent and the percentage by weight retained sieve is 50 percent, respectively.
The aim of this research is to experimentally study the application of powder coating sludge (PCS) and metakaolin as geopolymer. The PCS is a lot of waste which is released after the powder coating production process. While metakaolin comprises SiO2 and Al2O3 which can be used to produce geopolymer. Therefore, this study aimed to determine a suitable geopolymer mix ratio, using PCS as part of the mixture. This research also investigated the effect of metakaolin/PCS ratio, sodium hydroxide (NaOH)/sodium silicate (Na2SiO3) ratio, curing time, NaOH concentration and solid/liquid ratio on compressive strength of geopolymer. The coefficient of thermal conductivity was tested by using a suitable composition. Kaolin in this experiment was calcined at 700 °C for 2 h. Alkaline activators for molding were NaOH and Na2SiO3. Samples were hardened in an electric oven at 80 °C for 4 h before being removed from the moulds and cured at room temperature within 7, 14 and 28 days. Metakaolin/PCS ratios of 90:10, 80:20, 70:30 and 60:40, and solid/liquid ratios of 0.8 and 0.6 were performed. Concentration of NaOH were 6, 8, 10, 12 and 14 molars and NaOH/Na2SiO3 ratios were 1:1.5, 1:2 and 1:2.5, respectively. The experiments were conducted in triplicate. Results of 3 PCS tests showed that the highest composition of Al2O3 and SiO2 were 3.37 and 1.99 % w/w, respectively. The sample which is based on 60 % metakaolin and 40 % PCS, 10 molars NaOH, NaOH/ Na2SiO3 of 1:1.25, solid/liquid of 0.6 and curing time of 28 days had a maximum compressive strength of 81 kg/cm2, while the coefficient of thermal conductivity was 0.1766 W/(mk). Therefore, it can be concluded that the PCS has the potential to partially replace metakaolin as geopolymers material.
HIGHLIGHTS
Geopolymer comprises alumina (Al2O3) and silica (SiO2) and the advantages of geopolymer production are environmentally friendly and reduce energy consumption
The appropriate metakaolin/PCS ratio and concentration of activators provide the highest compressive strength
The geopolymer of this study has low thermal conductivity coefficient therefore it is a good insulation material
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