본 연구에서는 서로 다른 열전달 특성을 가진 탄소섬유 전기발열체와 경유온풍난방기가 온실 내부의 온습도, 에너지소비, 작물생육 등에 미치는 영향을 분석하기 위해 오이 재배 단동온실에 대한 난방 비교시험을 수행하였다. 전기발열체 온실에서 난방용량이 온실 환경과 난방기 운전에 미치는 영향을 분석하기 위해 온실에 6, 9, 16kW의 전력을 각각 공급한 결과 전기발열체 ON-OFF 주기는 각각 9, 11, 15회로 비례하여 증가하였으며 온실 내부 평균온도는 각각 15.2, 15.3, 15.6oC, 평균상대습도는 84, 81, 76%로 나타나 난방 용량이 클수록 온실내부 온도는 높고, 상대습도는 낮게 나타났다. 또한 6, 9kW 가동 시 하부온도가 상부보다 0.1oC 높았으며 16kW 가동 시는 상부 평균온도가 하부보다 0.2oC 높았다. 전기발 열체와 경유온풍난방기의 비교 시험에서는 난방 시 온실 상부와 하부의 온도차가 전기발열체 온실이 0.1~0.2oC로 경유온풍난방기 온실의 0.5~0.6oC보다 작았으며, 온실 상류와 하류의 온도차는 전기발열체 온실이 0~0.1oC로 경 유온풍난방기 온실의 1.3~1.4oC보다 작아 정밀한 온도관리가 가능하였다. 난방기간 동안 사용한 에너지사용량은 경유온풍난방기 온실이 경유 867L를, 전기발열체 온실이 전력량 8,959kWh를 사용하였으며, 난방비용은 각각 607 천원과 403천원이 소요되어 전기발열체 온실에서 약 34%의 비용절감 효과가 있었다. 전기발열체 온실의 경우 상대적으로 군락 상하부의 환경관리가 균일하여 초장을 비롯한 전반적 생육상황이 경유온풍난방기 온실보다 좋았으나 통계적으로 유의한 차이는 없었으며, 수확량 역시 전기발열체 온실의 작물군락 하부 온도가 경유온풍 난방기 온실보다 1.3oC 더 높게 관리되어 4.3% 증수효과가 있었으나 통계적으로 유의한 차이는 없었다. 원예 시설의 최적 난방 관리를 위해서는 각 난방기의 열전달 특성에 기초하여 난방기 용량, 배치, 열분배 방법에 대한 설계가 요구되며, 전열선 형태의 난방기 역시 작물형상 및 재배방법을 고려하여 전열선의 개수, 위치, 방열 온도 등에 대한 설계가 필요한 것으로 판단되었다.

This is fundamental study to apply the waste edible-oil utilization technology using cooking oil. Especially, this study was carried out to apply a hot air heater using the waste edible-oil. This waste edible-oil hot air heater was a fuel supply equipment, a combustion and a indirect heat exchanger. waste edible-oil hot air heater was remodeled and manufactured by modification of a heavy oil hot air heater of a heating capacity 40,000kcal/h, changing fuel supplying system fitted with the waste edible-oil. An experimental apparatus supplies waste edible-oil, which is heated with intake oil, into an intake fuel injection nozzle of the combustion equipment. As the result, heavy oil, light oil and waste edible-oil Caloric value were 10,000kcal/kg, 10,890 kcal/kg and 9,370 kcal/kg. The waste edible-oil hot air heater performance showed that air temperature at inlet , outlet and exhaust gas were 23℃, 59∼63℃, 280℃ respectively. heat rating and thermal efficiency showed that in hot air heater was 683,333kJ/h, 78% respectively. It was found that CO, CO2 were 13ppm, 13.1%. waste edible-oil consumption rate was 22.1ℓ/h.

This experiment was conducted to investigate the effect of wa-song (Orostachys japonicus A. Berger) extracts on the oxidative stability of edible oil. Wa-song was dried from hot air (HWE) and freeze (FWE), and then they were extracted by hot water. The different levels (0.1, 0.5 and 1.0 g/100 mL) of HWE and FWE were added to soybean oil and lard. The chromaticity of edible oils was generally increased with prolonged heating time and HWE was higher than FWE. The anisidine value showed significant increase during heating for 48 hrs. After heating for 48 hrs, it was lower than control, except for HWE added sample of 0.5 and 1.0 g/100 mL, FWE added sample of 1.0 g/ 100 mL. In lard, it was lower in sample added wa-song extract than control. The acid value was not significant by added amount of wa-song. Its value in HWE added sample was lower than FWE, after heating for 48 hrs. POV was lower HWE than FWE, also. After heating for 24 hrs, TBA values in soybean oil containing HWE and FWE added sample was lower than control. In lard, its value in HWE and FWE added sample was lower than control during heating for 12~48 hrs. Therefore, those results suggested that HWE has higher antioxidant activity than FWE added sample, and then oxidative stability of HWE in edible oil was more potential for lard during its heating.

: In this experiment, three samples of oils were used. These oils were hydrated soybean oil, pure soybean oil and regular soybean oil. Oil was used after heating at 235-240℃ every four hours term and total heating hours was 16 hours. The physio-chemical analysis and sensory evaluation were performed on these oils. The hydrated soybean oil showed lower acid, peroxide and carbonyl value than the other two oils (p〈0.05 or p〈0.001). The other two oils were more affected in rancidity than the hydrated soybean oil. In color test, whereas L value lowed during the heating time, a and b value increased during the heating time. The tendency of high L value and low b value in a long-time heating was more apparant on the pure soybean oil and the regular soybean oil than on the hydrated soybean oil (p〈0.05). In sensory evaluation, color and rancidity order increased during the heating time. The hydrated soybean oil showed color and rancidity order than the other two oils. In overall quality test, the pure and regular soybean oil that had been used for 12 and 16 hour were not preferable. The hydrated soybean oil that had been used for 16 hour were not preferable. In sensory evaluation, the hydrated soybean oil, the pure and regular soybean oil did not show a apparent difference, although the hydrated soybean oil had a little better scores on the overall quality.

국산 소형어선용 예연소실식 디젤기관의 연료유를 가열할 경우, 연소특성 및 기관성능에 미치는 영향에 관하여 실험한 결과를 요약하면 다음과 같다. 1) 연료유 분사시작점은 연료유 가열온도의 증가에 따라 늦어지는 경향을 나타냈으며, 특히 저부하 운전시 늦어지는 경향이 현저했다. 2) 연소최고압력점은 연료유 가열온도의 증가에 따라 늦어졌으며, 연소최고압력은 연료유 가열온도 증가에 따라 감소하였으나 부하의 증가에 따라 증가하는 경향을 나타내었다. 3) 연료소비율은 부하의 증가에 따라 감소하였으며, 연료소비율이 가장 작은 연료유의 최적가열온도는 150℃부근임을 나타내고 있다. 4) 그을음농도는 부하와 연료유 가열온도의 증가에 따라 증가하는 경향을 나타냈다.

The amount of sewage treatment has been increasing year by year as the small and medium sized cities grow in Korea. Besides, the treatment of sludge has been more significant owing to the total ban on disposal of organic sludge in a landfill since April 2004 and ocean dumping of organic waste since December 2013. In this research, we studied the drying characteristics of sewage sludge by indirect heating device using thermal oil. The indirect heating device operated in a batch for 16 hours according to the variation of drying temperature between 100 and 200oC and the initial input weight of each type of sewage sludge was equally 60 kg. As a result, the moisture content in raw, excess and mixed sludge became lower than 10% under 14 hours at 160oC. The average water loss rate of raw, excess and mixed sludge is 0.436 g-wet/ min, 0.362 g-wet/min and 0.367 g-wet/min respectively at this stage. Therefore, the raw sludge can be dried well, using indirect heating device in sewage treatment plant. Also, it is better to dry raw sludge or excess sludge alone than mixed sludge because each type of sludge does not make synergistic effect but counter effect when they are together.