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수평 내면 핀관내에서 R-22와 대체 냉매의 증발 열전달 비교
노건상,박기원,정재천,오후규 여수대학교 1998 論文集 Vol.12 No.2
Worldwide energy consumption has been recently increasing enormously, especially in refrigeration and air conditioning industries. As a result of this increase, atmospheric hydrocarbon and other gas levels have increased so that they may be a source of world environmental problems. Therefore, new research was started to overcome the environmental problems, like the destruction of the ozone layer and the warming of Earth's temperature, by the use of natural refrigerants as substitutes for the freon refrigerant. In this paper, evaporation heat transfer of global heat pump using grooved inner tube was studied. New natural refrigerants R-290 and HCFC refrigerant R-22 were used. The local heat transfer coefficient was decreased according to the evaporation process. Moreover, the increment of heat transfer coefficient was found in R-290 refrigerant. Average heat transfer coefficient was obtained the higher value in R-290 refrigerant than R-22. Comparing the heat transfer coefficient between experimental result and simulation data of other's, the Shah's correlated equation was closely assimilated to the author's experimental results.
播種期, 苗令 및 土壤水分不足이 黃色種 담배의 生育 및 收量에 미치는 影響
盧載榮,申周植,朴然圭,孫錫龍 충북대학교 엽연초연구소 1984 煙草硏究 Vol.11 No.-
This experiment was conducted to study the influence of environment cultural method and their interaction on the growth and yield components of flue-cured tobacco. Applied variety was NC 2326, and was treated by sowing time(Mar. 11, Mar. 21 and Mar.31), seedling age (40,50 and 60 day) and soil moisture stress period (20 days from 10, 20 and 30 days after setting). The results are summarized as follows. 1.During growing period, stem height, length and width of the largest leaf and total leaves were affected remarkably by the treatments. 2.Soil moisture stress period affected more the characters of tobacco plants than other factors. 3.The tobacco plant treated by early stage soil moisture stress (period from 10 to 30 days after setting) made the early growth very poor, and that tobacco plant showed poor growth until 45 to 50 days after setting. 4.Early sowing, 40 day seedling and early stage soil moisture stress made the plant type sylindrical, and late sowing and 50 to 60 day seedling made the plant type cone shape. 5.Number of total leaves and harvested leaves, leaf area per plant percentage of dry matter of leaf and specific leaf weight decreased by the treatment of soil moisture stress during early and middle part of maximum growth stage. 6.There were little differences of yield among the treatment of different sowing time and seedling age. Early sowing increased the thickness of leaf and weight per unit leaf area, and decreased number of total leaves and specific leaf weight. Number of total and harvested leaves and specific leaf weight of cured leaves were high in the plot of 60-day seedling 40-day seedling showed heavy weight of unit leaf area and low specific leaf weight of cured leaves. 7.From the point of view of interaction between sowing time and seedling age, early sowing (Mar. 11) with 60-day seedling, middle sowing (Mar. 21) with 50-day seedling and late sowing (Mar. 31) with 40-day seedling are recommended. 8.Rapid growth of early growing stage was shown in the plot of adequate soil moisture and late sowing (Mar. 31) with 50-day to 60-day seedling. 9.From the point of standard quality of cured leaves, sowing time can be shifted until late March. And to fix the sowing time, It should be considered that the maximum growth stage and the harvesting time of cutter and leaf would not match with severe drought of May and rainy season of early summer respectively.
냉동ㆍ공조 장치에서 R-22와 자연냉매 R-290의 열전달과 사이클 특성
정재천,박기원,노건상,오후규 여수대학교 1998 論文集 Vol.12 No.2
A basic heat pump system was designed and manufactured, in which a pair of bare tube was constructed as main heat exchanger. New natural refrigerants R-290 and HCFC refrigerant R-22 were used. In this paper, cycle characteristics of global heat pump, evaporation and condensation heat transfer characteristics were studied and a basic data base for the optimum design of refrigeration and air-conditioning systems was obtained. On the condensing and evaporating heat transfer characteristics, the average heat transfer coefficient was obtained the higher value in R-290 than R-22 refrigerant. Characteristics of heat pump cycle were researched based on the compressor shaft power, cooling capacity and coefficient of performance. From these results, the heat pump cycle characteristics were more affected from the refrigerant properties and operating conditions. Considering the results, R-290 refrigerant has a sufficient ability to substitute R-22 due to its higher performance.