• Journal of the Korea Organic Resources Recycling Association
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• v.13 no.2
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• pp.74-84
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• 2005

The objectives of this study was to investigate the improvement of thermal kinetics for disposal of sewage sludge using thermal wind drying. The operational parameters varied are the temperature of $130{\sim}170^{\circ}C$ and evaporation velocity WD. Important parameters effect on thermal kinetics for evaporation of water in sewage sludge studied include the drying time, water content of sewage sludge, solids amount of sewage sludge(TS%) by the varied temperature. The saturation point of water evaporation was observed at the drying time of 60 min in conditions of drying temperature $170^{\circ}C$ and drying time of 120 min by drying temperature $130^{\circ}C$ and WD=0.95 m/s. Operation at drying temperature of $170^{\circ}C$ led to higher rate of evaporation than those 130, $150^{\circ}C$ at WD=1.0 m/s and WD=1.0 m/s was higher than WD=0.5 m/s at drying temperature of $130^{\circ}C$.

• Korean Chemical Engineering Research
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• v.40 no.6
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• pp.681-686
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• 2002

In the industrial field, the theory of drying process is different from the practical application, and it is effective to reduce energy by recirculation of the heat of exhausting gas. But the study of this field may not be performed still. The cure properties of the urea resin moulding compounds was investigated according to drying temperature, drying time, recycle rate of exhausting gas and moulding temperature in the process of drying and moulding. We obtained the following results; water content of material decreases with increasing drying time and drying temperature, and the rate of drying also decreases with increasing recycle rate of exhausting gas. Specially, The cure fluidity of the urea resin moulding compounds decreases, with increasing drying temperature, recycle rate of exhausting gas and moulding temperature. And the correlation equations on water content and cure fluidity of the urea resin moulding material were obtained through a regression analysis of experimental data.

• Journal of the Korean Society of Food Science and Nutrition
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• v.20 no.5
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• pp.503-508
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• 1991

The salted and dried mullet(Mugil Japonicus) roe had about 42% of protein and 41% of lipid content as major compoments. Therefore the lipid oxidation and the deterioration of protein occurred during drying and storage periods. In order to keep the good quality of the dried roe, acid, peroxide, thiobarbituric acid value and the contitutional amino acid were studied in the different drying air velocities at the conditions of 60% R.H. and $20^{\circ}C$ of drying air temperature. The optimum air velocity showed 2m/sec, which was excellently superior to the lipid and protein quality than those of other air velocities on the dried mullet roe. The drying period shortened from 20 days in the conventional processing method to 7 days in the modified processing method that had 2m/sec of drying air velocity. The drying rate curve had only a falling-rate drying period and not to have a constant-rate drying period.

• Journal of Environmental Science International
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• v.30 no.2
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• pp.135-143
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• 2021

This study executed evaluation of drying characteristics based on the polymer injection rate (8%, 10% and 12%) and the drying method[NIF(near-infrared ray). According to this study analyzed VS, VS/TS, and calorific value compared with 'the auxiliary fuel standard of the thermoelectric power plant and the combined heat & power plant'. The results are as follows. In the case of NIR, the VS was slightly changed at the early stage of the material preheating period and the constant drying rate period with low moisture evaporation. But VS reduction was shown higher as moisture was dried. In the case of non-digested sludge with high VS content, the VS reduction rate by drying was shown lower than that of digested sludge. As the flocculant injection rate increased, the VS loss due th drying was found to be small. Also, the higher the flocculant injection rate was the longer the drying time. Especially, in the case of the NIR drying equipment, as the moisture content of sewage sludge decreased(moisture content 20~40%), the loss of net VS also showed a tendency to increase sharply. It is shown that the high calorific value according to the drying time of the non-digested sludge was changed from 590 kcaℓ/kg to 3,005 kcaℓ/kg and from 539 kcaℓ/kg to 2,796 kcaℓ/kg.

• Journal of Forest and Environmental Science
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• v.33 no.1
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• pp.33-38
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• 2017

In this study, spray-drying yield and morphological characterization of spray-dried cellulose nanofibril (CNF) and TEMPO-oxidized nanocellulose (TONC) depending on spray-drying condition and surfactant addition was investigated. As spray-drying temperature increased, the yield of spray-dried CNF was increased. The highest spray-drying yields in both nanocelluloses were found at didecyl dimethyl ammonium chloride (DDAC) addition of 2.5 phr at all investigated temperatures. The spray-dried CNF was the sphere-like particle, but the spray-dried TONC showed both rod and sphere-like morphology. The average diameter of spray-dried CNF was decreased with increasing DDAC addition amount, resulting in the increase of specific surface area.

• Journal of the Korean Ceramic Society
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• v.40 no.5
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• pp.501-505
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• 2003

SrZrO$_3$ resistive oxides on Ag tapes were prepared by the sol-gel and dip coating method to investigate the effect of PVP content and drying condition on microstructure of the films. Although the film thickness increased with the addition of PVP, the amount of PVP and heat treatment were not effective to reduction of formation of microcracks at the films. However, lower drying temperature and longer drying time were beneficial to control the microcracks of the SrZrO$_3$ films, indicating that the microcracking of the films was governed primarily by the drying condition.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.30 no.2
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• pp.40-46
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• 1998

This study was aimed to investigate any improvement of dewatering and energy saving on the papermaking process when the various types of fillers were used, i.e., clay, talc and grounded calcium carbonate (GCC). Cationic polyelectrolyte and alum coagulants neutralized the surface charge of the filler particles and the filler particles were coagulated. The rates of dewatering and drying were investigated. The results indicated that clay tended to intense anion, while talc and GCC tended to anion trend nearly to neutrality. Clay and talc added with EPI-DMA, P-DADMAC and alum respectively as optimum levels showed a significant efficiency on the dewatering and the turbidity dissipation. However, the turbidity and dewatering rate of GCC decreased, when GCC was added with EPI-DMA and P-DADMAC respectively Drying rate of clay was increased when coagulant added. However drying rates of talc and GCC were not affected by coagulant, while the apprarent drying time of talc and GCC in the absence of any coagulant was shorter than the clay in the presence of a coagulant. The result confirmed that talc or GCC was more efficient than clay on the dewatering and drying, which is consistent with a general knowledge in the collodal science.

• Journal of the Korean Ceramic Society
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• v.40 no.8
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• pp.798-803
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• 2003

In synthesis of nano powders, the hard agglomeration for the synthesized powders occurred during the drying processing. In order to avoid hard agglomeration in particles the freeze drying process was used in this experiment. e fabricated the Yttira-Doped Ceria(YDC) nano powder by co-precipitation. Starting materials used in experiments were the cerium(III) nitrate and yttrium(III) nitrate solution with 야-water, which two solutions were mixed and then the precipitated hydroxides were prepared for adding sodium hydroxide. The co-precipitated powders were dried by the thermal drying at 8$0^{\circ}C$ for 24 h and by freeze drying at -4$0^{\circ}C$, 30 mtorr for 72 h. The lattice parameter and crystallite size as a function of calcination temperature was characterized by XRD analysis. The lattice parameter of YDC was decreased with addition amount of yttrium and was estimated as 5.401683 $\AA$ at $700^{\circ}C$. Crystallite size were calculated by XRD-LB method, and morphologies were confirmed with the observation of TEM and SEM. The freeze dried YDC powders had medium diameter of 17 nm with more uniform size distribution than the thermal dried YDC posers, which were mainly ascribed to the difference of agglomerates formation during drying stage.

• Journal of the Korean Applied Science and Technology
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• v.28 no.3
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• pp.367-373
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• 2011

This research is a basic researching process for producing solid fuel that mixing paper sludge and Heat Transfer Medium Oil. Under the presence of Heat Transfer Medium Oil, paper sludge is heated and dried with home appliance microwave for comparing drying efficiency and energy efficiency of different types of drying method. As a result, Heat Transfer Medium Oil and paper mixing case of drying method, OMD, is the most efficient way to shorten the time for evaporating moisture in the paper sludge. In addition, heat transfer effect and density is increased with adding Heat Transfer Medium Oil by microwave. Future more, OMD's energy cost for evaporating whole moisture is 78% cheaper than MD. Also, OMD process shows the best energy efficiency with comparing other process. Evaporation rate of paper sludge evaporation process with microwave is 11.66% increased by adding Heat Transfer Medium Oil 150g. Preheating Heat Transfer Medium Oil or improving different ways injecting Heat Transfer Medium Oil is a good way to increase a rate of initiative moisture evaporation process.

• Journal of Biosystems Engineering
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• v.37 no.6
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• pp.385-397
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• 2012

Purpose: Drying characteristics of sawdust was studied under batch mode using lab scale microwave dryer. The objective of this study was to investigate the effect of material load and microwave output power on drying characteristics of sawdust. Methods: Material load and microwave output power were varied from 23 to 186 g and 530 to 370 W respectively. Different kinetic models were tested to fit the drying rates of sawdust. Similarly, the activation energy was calculated by employing the Arrhenius equation. Results: The drying efficiency increased considerably, whereas the specific energy consumption significantly decreased with increase in material load and microwave output power. The cumulative energy efficiency increased by 9%, and the specific energy consumption decreased by 8% when the material load was increased from 23 to 186 g. The effective diffusivity increased with decrease in material load and increase in microwave output power. The previously published model gave the best fit for data points with $R^2$ and RMSE values of 0.999 and 0.01, respectively. Conclusions: The data obtained from this study could be used as a basis for modeling of large scale industrial microwave dryers for the pellet production.