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.

In this paper, numerical simulations are performed for the drying process of potato chip in a microwave oven with multiple waveguides, with the purpose of enhancing the uniformity in temperature distribution. A simulation model is built and simulated using COMSOL Multiphysics software. The simulation model uses 5 different positions of waveguides to see whether it affects the heat distribution in the material. In order to know the final temperature result of the material after it comes out of the cavity on a moving conveyor belt, the average temperature values along the direction of the conveyor belt motion are calculated and plotted. From the results, the best waveguide position is determined to get the best temperature distribution in the potato chips.

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.

In this study, we evaluated the effect of the type of sewage sludge (digested, non digested) on drying efficiency according to the polymer injection rate. The drying characteristics were shown using a near-infrared ray (NIR) and a microwave. As a result of the drying characteristics with NIR at a polymer dose ratio of 8%, the heating up period is up to 6 minutes after the start of the drying experiment. Afterwards, the constant rate drying period of the digested sludge (A, C and G sites) was 6 minute → 18 minute, showing a rapid decrease in moisture. On the other hand, non digested sludge (B, D, E, F, H, I, J and K sites) showed gradual drying characteristics compared to digested sludge until complete drying (10%). As the polymer dose ratio of 10% and 12%, the heating up period for digested sludge is up to 6 minute after the start of the experiment. Afterwards, the constant rate drying period of the digested sludge was 6 minute → 20 minute, showing a rapid decrease in moisture. On the other hand, the heating up period of non digested sludge was up to 10 minute after the start of the experiment, and the constant rate drying period was 10 minute → 22 minute, which was shorter than digested sludge. As a result of the drying characteristics with microwave at a polymer dose ratio of 8%, 10% and 12%, the constant rate drying period the digested sludge was 4 minute → 20~22 minute, showing a rapid decrease in moisture. On the other hand, non digested sludge of the constant rate drying period was 4 minute → 22~30 minute, which was longer than digested sludge.

The technology for sludge drying using a microwave is a primary process in producing solid refuse fuel in the waste-toresource process. In this paper, the drying efficiency is improved by investigating chamber types such as square and circle with various mechanical conditions such as the magnetron power, the height of microwave irradiation, and the sludge thickness. In identical conditions, the moisture content was generally uniform in the circle chamber due to the uniform distribution of microwave irradiation, and the drying efficiency was higher in the circle chamber compared to the square chamber. In the case of the circle chamber, the drying rate was increased by more than 30% and the energy for sludge drying 507.9 kcal/kg of water was reduced. Hence, the application of a circle chamber should save energy consumption in sludge drying.

목재 건조의 용이성 및 품질확보, 2차 보존처리를 위한 기초자료 확보를 위해 초고주파를 이용한 캐나다산 직수입 미송의 가열 건조 특성은 다음과 같다. 초고주파 조사 후 목재 내부 온도변화 곡선을 분석한 결과 원주목은 3kW 30분 및 120분 가열 할 경우, 판목은 4kW 3분 및 9분 가열 시 안정적인 열분포와 소비 열량, 표면 함수분포 확보가 가능한 것으로 나타났다. 특히 초고주파 가열에 따른 표면 함수분포는 매우 균일한 Leveling이 이루어진 것으로 나타났으며, 함수 감소율도 중량대비 30% 이상인 것으로 나타나 건조효율이 우수한 것으로 나타났다. 또한 소비 열량 분석 결과에 따라 2차 액상 보존처리를 위한 침지 시 대량의 보존처리제 침투가 가능할 것으로 사료되므로, 초고주파 가열 목재는 빠른 함수감소 및 건조 특성과 많은 열량의 소비가 가능하여 산업재로의 사용 및 2차 응용제품 개발에 우수한 특성이 있는 것으로 사료된다.

배연탈황석고 및 인산부산석고에 함유된 부착수분을 마이크로파에 의한 직접 내부 가열 방법으로 증발시켜 건조하고자 하였다. 700 W, 1,000 W, 1,700 W의 출력인 마그네트론에서 발생된 2.45 GHz의 마이크로파로 배연탈황석고와 인산부산석고를 가열한 결과, 마이크로파 출력의 세기를 700 W에서 1,700 W로 높임에 따라 부착수의 증발시간이 10분에서 3분으로 단축되었고, 이수석고는 베타형 반수석고로 변질되었다. 그러나 베타형 반수석고는 무수석고로 변질되지 않았다.