• Journal of the Korean Wood Science and Technology
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• v.52 no.1
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• pp.1-12
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• 2024

Betung bamboo (Dendrocalamus asper) is used as a building and handicraft material in Indonesia; however, bamboo needs to be dried to increase its stability. This study aimed to evaluate the efficiency of drying bamboo using solar energy and different drying oven designs. The betung bamboo pieces were dried using a direct solar dryer (direct drying) and an indirect solar dryer (indirect drying) and then the decrease in levels that occurred based on the relative humidity (RH) and temperature values achieved in the two dryers were compared. The highest average temperature in the direct indirect drying oven compartment was 60.1 ± 13.1℃ with 19.9 ± 16.4% RH and 60.2 ± 11.9℃ with 19.5 ± 15.5% RH, respectively. The drying defect in indirect drying was lower than that in direct drying, and indirect drying had a 61.7% greater average water loss than direct drying with significant difference (95%, analysis of variance) based on water loss/compartment volume parameters. Thus, the solar drying oven can be used to air-dry bamboo (14%) for 7 d from an initial moisture content of 70%-80% in bamboo strips. The results of this research can be used for small-scale bamboo processing industries that have limited use of electrical energy with quite good results.

• Journal of the Korean Wood Science and Technology
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• v.35 no.2
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• pp.23-28
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• 2007

Wood fuel must be dried before combustion to minimize the energy loss. Sawdust of Japanese red pine was dried in a direct contact thermal screw dryer to investigate the drying characteristics of sawdust as a raw material for bio-fuel. Average drying rate and energy efficiency was 1.4%/min and 69.23% at $100^{\circ}C$, respectively, and those at $120^{\circ}C$ was 2.1%/min and 71.03%, respectively.

• Journal of Korea Foresty Energy
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• v.21 no.3
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• pp.10-17
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• 2002

This study was carried out to investigate a heat treatment condition and suitable drying schedule of bamboo material(Phyllostachys nigra var. henonis) for a vertical flute with small-notched bamboo. It is very important to prevent drying defects during its drying process. We investigated the effort of heat treatment the most suitable drying schedule for small-notched bamboo vertical flute without drying defects in this research. A direct heat treatment method and drying conditions of 3($20^{\circ}C$ 65%, $40^{\circ}C$ 40%, and dry at air condition) were applied to the Bamboo specimen that felled in several areas for a month. The result suggested that the most suitable drying schedule with the less split and the shortest time was to dry at $40^{\circ}C$, 40% condition and it was useful to direct heat-treatment because of reducing the number and size of split during drying bamboo.

• Journal of Korean Society of Water and Wastewater
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• v.38 no.3
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• pp.155-164
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• 2024

There are two primary sludge drying methods such as the direct heating microwave method and the indirect heating steam one. In this study, the drying treatment facility at sewage treatment plant A applied both of these drying methods. The research aimed to investigate the optimal operation approach for the drying facility, considering the input sludge and the moisture content data after the drying process. Moisture content and removal rate data were executed at the research facility from January 2016 to December 2018. First, the microwave, a direct heating drying method, performed intensive drying only on the outer surface of the sludge by directly applying heat to the sludge using far infrared rays, so effective sludge drying was not achieved. On the other hand, the steam method of the indirect heating method used steam from a gas boiler to maximize the utilization of the heat transfer area and reduce energy of the dryer, resulting in an effective sludge drying efficiency. The sludge moisture content brought into the sludge drying facility was about 80%, but the moisture content of the sludge that went through the drying facility was less than 10% of the design standard. Therefore, the steam method of the indirect heating method is more effective than the microwave method of the previous direct heating method and is more effective for maintenance It has proven that it is an efficient method of operating construction facilities.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.203-208
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• 2007

Drying characteristics are confirmed by experiment to a printing machine which use Gravure ink or metal ink for an optimum design of direct radiation drying system room using NIR. As a result, Drying is easily accomplished in short distance and low moving speed in Gravure ink, but drying is dropped in metal ink because of oil. This confirmed that the development of water metal ink had to be proceeded to accomplish a perfect drying condition.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.1
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• pp.51-58
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• 2020

As interest in lunar exploration increases, studies on lunar surface environment simulation including a lunar soil simulant are being conducted. One of the problems when creating a vacuum environment with lunar soil is that it takes long time to reach high vacuum due to outgas from the soil. Most of the outgas is water, and the time to reach high vacuum can be significantly reduced by a pretreatment process that removes moisture adhering to the surface of the lunar soil before putting soil into a vacuum chamber. The existing soil drying methods were examined to determine how these methods were effective to remove moisture from the lunar simulant soil. Drying experiments of lunar soil samples were carried out using a dry oven, a microwave oven, direct heating method and a vacuum oven, and the results of the drying experiment were presented. Drying soil at 110℃ using a dry oven and drying soil by a microwave oven were not enough to remove moisture, and vacuum oven drying method and direct heating drying method at more than 200℃ were effective in water removal.

• Plant Journal
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• v.5 no.4
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• pp.73-79
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• 2009

Increase of consumption in limited coal reserves leads prices surging. As a result, iron works which produce products with coal are in difficulties. Accordingly, it is required a lot of research of using non-caking coal that is relatively low cost and has abundant reserves. Direct drying and indirect drying are two major methods of drying the coal. Recently, to minimize the needed calories and to save energy, using fluidbed or fluidizing method is a recent main trend of minimizing the size of the facility and maximizing energy efficiency. However there is also disadvantage such as increasing facility investment because of installing additional facilities in the latter part. In this study, we will have theoretical researches on the indirect drying method with heat exchange system which have been traditionally used. As a result it is expected to increase the efficiency of the facility operation.

• Korean Journal of Food Science and Technology
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• v.35 no.2
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• pp.329-333
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• 2003

Fruits of 'Manita', a red pepper cultivar, and 'HL', a cultivar bred for single-harvest, cultivated by direct sowing method were harvested simultaneously. The red fruits were freeze-, sun-, indoor-, hot-air $(65^{\circ}C)$, and excessive hot-air (50% longer time) dried. For Manita. ASTA values of freeze- and indoor-dried red pepper were the highest $(153.6{\sim}168.4)$, and those of sun- and hot air-dried ones were $119.2{\sim}131.5$. Excessive hot-air drying decreased the redness by about $9{\sim}15%$ compared to normal hot-air drying. For HL, ASTA values $(150.3{\sim}171.7)$ of indoor-dried red peppers were much higher than other dried peppers. Red pigment in HL was destroyed easily during sun drying, showing values of only $49.2{\sim}69.2$. By excessive hot-air drying, the redness did not decrease, compared to normal hot-air drying. The organic acid contents of both cultivars were higher in sun- and hot-air-dried ones than freeze- and indoor-dried ones. Copsaicinoid contents of both cultivars decreased up to 22% by excessive hot-air drying compared to normal hot-air drying. Sugar contents were lower in all drying methods other than freeze drying for both cultivars.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.3
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• pp.588-594
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• 2001

The aim of this paper is to develop the low temperature vacuum dryer, with low initial investments and operating costs, easy operating method and trouble-free operation Usally operations just below atmospheric pressure, as with direct dryers, but some are built for vacuum operation with pressure as low 50 mmHg abs. The lowers the boiling point to $39^{\circ}C$ The experimental data of quantitative analysis for using practically were obtained by the constant drying rate period and reducing drying rate period according to the temperature of hot water which is the experimental parameters of present experiment. As the results, it took about 20 hours for material to reach about 18% of the final moisture content is order to store products for a long time about 450% of the early moisture content at the beginning of drying and maximum drying rate comes to about 0.30 kg/m2hr at about 350% of the moisture content.

• Journal of Power System Engineering
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• v.14 no.4
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• pp.23-28
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• 2010

Of the roughly four million known substances, about 60,000 are processed and sold ; many of these must be dried. Many materials are processed in the liquid state - ideal for mixing and reacting - but most products are needed or wanted as dry, or relatively dry, solids. Usually operation is just below atmospheric pressure, as with direct dryers, but some are built for vacuum operation with pressures as low as 26.66kPa abs.. In spite of the global-class aquiculture agriculture and fisheries technology of our country, the processing technologies are lags behind the other nations relatively. These problems are considered to be caused directly by the lack of drying technologies. This paper is concerned to the experimental results of drying heat transfer characteristics for the green energy type vacuum dryer for the high quality agriculture and fisheries production.