The present study demonstrates the effect of raw powder on the pore structure of porous W-Ni prepared by freeze drying of camphene-based slurries and sintering process. The reduction behavior of WO3 and WO3-NiO powders is analyzed by a temperature programmed reduction method in Ar-10% H2 atmosphere. After heat treatment in hydrogen atmosphere, WO3- NiO powder mixture is completely converted to metallic W without any reaction phases. Camphene slurries with oxide powders are frozen at −30 oC, and pores in the frozen specimens are generated by sublimation of the camphene during drying in air. The green bodies are hydrogen-reduced at 800 oC and sintered at 1000 oC for 1 h. The sintered samples show large and aligned parallel pores to the camphene growth direction, and small pores in the internal wall of large pores. The strut between large pores, prepared from pure WO3 powder, consists of very fine particles with partially necking between the particles. In contrast, the strut densification is clearly observed in the Ni-added W sample due to the enhanced mass transport in activation sintering.

In this paper, we investigate how the power consumption of a heat pump dryer depends on various factors in the drying process by analyzing variables that affect the power consumption. Since there are in general many variables that affect the power consumption, for a feasible analysis, we utilize the principal component analysis to reduce the number of variables (or dimensionality) to two or three. We find that the first component is correlated positively to the entrance temperature of various devices such as compressor, expander, evaporator, and the second, negatively to condenser. We then model the power consumption as a multiple regression with two and/or three transformed variables of the selected principal components. We find that fitted value from the multiple regression explains 80~90% of the observed value of the power consumption. This results can be applied to a more elaborate control of the power consumption in the heat pump dryer.

콤바인을 이용하여 수확하는 곡물은 일반적으로 저장에 용이한 적정함수율보다 높은 경우가 많다. 이것은 곡물의 수확과정에서 손실율을 최소화하기 위한 방법 중에 하나이지만, 수확 후 현장에서 자연건조를 통한 저장 시 필요로 하는 적정함수율까지 낮추는 것은 불가능하다. 따라서 곡물을 수확한 후, 저장 시 필요한 적정함수율을 맞추기 위해서 인위적으로 화석연료 등을 이용하여 건조하는 경우가 많다. 그러나, 곡물건조기 등에 사용되는 화석연료는 곡물건조 시 온실가스의 배출 등의 환경 문제뿐만 아니라, 농가에서는 경제적인 부담이 되고 있다. 따라서 본 연구에서는 곡물 건조를 위해서 수확과정에서 콤바인 배기열의 이용 가능성에 대한 기초자료를 활용하고자 수행하였다. 이를 위해 콤바인의 선별부와 이송부를 실제 제원과 동일하게 제작한 뒤 배기열을 이용하여서 곡물의 함수율변화를 측정하였다. 그 결과, 각각의 실험장치에서 평균 0.166, 0.126%의 곡물 함수율이 감소하였고, 전체적으로 약 0.3%의 함수율이 감소되었다. 이는 배기열을 이용한 곡물 건조방법의 가능성이 있는 것으로 판단되었다.

In this paper, we investigate the statistical correlation of the time series for temperature measured at the heat box in the automobile drying process. We show, in terms of the sample variance, that a significant non-linear correlation exists in the time series that consist of absolute temperature changes. To investigate further the non-linear correlation, we utilize the volatility, an important concept in the financial market, and induce volatility time series from absolute temperature changes. We analyze the time series of volatilities in terms of the de-trended fluctuation analysis (DFA), a method especially suitable for testing the long-range correlation of non-stationary data, from the correlation perspective. We uncover that the volatility exhibits a long-range correlation regardless of the window size. We also analyze the cross correlation between two (inlet and outlet) volatility time series to characterize any correlation between the two, and disclose the dependence of the correlation strength on the time lag. These results can contribute as important factors to the modeling of forecasting and management of the heat box’s temperature.

Porous Ti-systems with unidirectionally aligned channels were synthesized by freeze-drying and a heat treatment process. TiH2 powder and camphene were used as the source materials of Ti and sublimable vehicles, respectively. Camphene slurries with TiH2 content of 10 and 15 vol% were prepared by milling at 50˚C with a small amount of oligomeric polyester dispersant. Freezing of the slurry was done in a Teflon cylinder attached to a copper bottom plate cooled at -25˚C while unidirectionally controlling the growth direction of the camphene. Pores were generated subsequently by sublimation of the camphene during drying in air for 48 h. The green body was heat-treated at 1100˚C for 1 h in a nitrogen and air atmosphere. XRD analysis revealed that the samples composed of TiN and TiO2 phase were dependent on the heat-treatment atmosphere. The sintered samples showed large pores of about 120 mm which were aligned parallel to the camphene growth direction. The internal wall of the large pores had relatively small pores with a dendritic structure due to the growth of camphene dendrite depending on the degree of nucleation and powder rearrangement in the slurry. These results suggest that a porous body with an appropriate microstructure can be successfully fabricated by freeze-drying and a controlled sintering process of a camphene/TiH2 slurry.

Hollow silica spheres were prepared by spray drying of precursor solution of colloidal silica. The precursor solution is composed of 10-20 nm colloidal silica dispersed in a water or ethanol-water mixture solvent with additives of tris hydroxymethyl aminomethane. The effect of pH and concentrations of the precursor and additives on the formation of hollow sphere particles was studied. The spray drying process parameters of the precursor feeding rate, inlet temperature, and gas flow rate are controlled to produce the hollow spherical silica. The mixed solvent of ethanol and water was preferred because it improved the hollowness of the spheres better than plain water did. It was possible to obtain hollow silica from high concentration of 14.3 wt% silica precursor with pH 3. The thermal conductivity and total solar reflectivity of the hollow silica sample was measured and compared with those values of other commercial insulating fillers of glass beads and TiO2 for applications of insulating paint, in which the glass beads are representative of the low thermal conductive fillers and the TiO2 is representative of infrared reflective fillers. The thermal conductivity of hollow silica was comparable to that of the glass beads and the total solar reflectivity was higher than that of TiO2.

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.

The researcher inquired drying characteristics by reflecter shape. Near infrared ray (NIR) is very useful in various drying field. The researcher compared and investigated, temperature about reflecter's shape with numerical analysis method and experimental method. The researcher also investigated about distance between a lamp and a drying target plate using experimental method. As far as a experimental method is concerned, the researcher used the thermal image processing system for changing distance between a lamp and a drying target plate into H=500mm, 600mm and 700mm. Also presented experimental results are compared about thermal image for temperature distribution at each cases. As a result, the researcher has come to the H=700mm about best result in this study.

국내 벼 건조기간의 기상조건에 적합한 열펌프를 설계, 제작하여 기본 성능을 측정하고, 건조온도 20-50oC 범위에서 벼 건조실험을 통하여 건조특성 및 소요에너지를 분석하였다. 열펌프는 건압축 냉동 사이클에서 냉동효과는 173.8 kJ/kg이었으며, 냉매순환량은 49.6 kg/hr이었다. 따라서, 성능계수는 5.5로 표준냉동사이클에서 냉매 R-22의 성능계수 4.0에 비해 높은 값을 나타내었으며, 목표 건조공기의 온도 30oC 및 상대습도 40%에 도달하는 시간은 6분 및 7분으로 만족할 만한 수준이었다. 건조온도와 곡온과의 온도차이는 건조온도 21.9oC에서는 약 1.5oC, 건조온도 48.7oC에서는 약 8.5oC로서, 건조실에서 상승한 곡온은 템퍼링실에서 충분한 냉각이 이루어지는 것으로 판단되었다. 건조온도 21.9, 30.7 38.8 및 48.7oC에서 건조속도는 0.29, 0.61, 0.85 및 1.25%/hr로 나타나 상용건조기와 유사한 수준이었다. 건조온도 21.9oC에서 소요에너지는 325 kJ/kg, 건조온도 30.7, 38.8 및 48.7oC에서는 667, 692 및 776 kJ/kg로 나타나 외기조건에 따라 건조소요에너지의 차이가 발생했지만, 화석연료를 사용하는 상용 화력건조기의 벼 건조 소요에너지 4,000-5,000 kJ/kg에 비해 평균 86% 절감되는 것으로 나타났다.

The treatment of sewage sludge using hydrothermal carbonization (HTC) can be an attractive alternative to conventional sludge disposal, but it should be accompanied by a drying process that uses Refuse-derived Fuel (RDF). However, the largest proportion of the energy demand in sludge-drying techniques is for heat sources, which has led to increased operation and maintenance costs. Recovering residual heat to apply to sludge drying significantly reduces both the operating cost and the greenhouse gas emissions. Suitable integration can be realized between drying technology and waste-to-energy (WtE) plants through the recovery of waste heat in WtE conversion as a heat source for sludge drying. This present paper investigates the indirect disk drying performance of the hydrothermal carbonization of sewage sludge using a low-temperature heat source in a laboratory and proposes an integration process with the drying technology of hydrothermal carbonization using waste heat. This paper concludes with experimental results that indirect disk drying technology can be applied in waste-heat recovery systems.