• Journal of the Korean Society of Tobacco Science
• /
• v.5 no.1
• /
• pp.79-85
• /
• 1983

The greenhouse bulk curing and drying system utilization of the direct solar energy was tested to evaluate that how much fuel could be saved for curing flue-cured tobacco at the Dae Gu Experiment Station (North latitude : $35^{\circ}$49'), in 1979-1982. The air temperature and total radiation were 19.0 to 38.5$^{\circ}C$ and 1311.0 to 1412.7 cal/$\textrm{cm}^2$/day during the 4 replicated curing test, respectively. The greenhouse bulk curing and drying system was able to cut fuel consumption by 32% compared with the conventional bulk curing barn. We could obtain almost same utilization efficiency of solar energy in 1982 compare with normal year, mainly increasing the heat receiving area.

• Korean Journal of Agricultural Science
• /
• v.10 no.1
• /
• pp.156-165
• /
• 1983

This experiment was carried out to elucidate the drying characteristics of onion and dehumidifying effect of air using the silica gel and to reuse it by solar collector. The results were summarized as follows. 1. It takes 14hours to regenerate to silica gel of 8% moisture content from saturated silica gel in conditions of $28^{\circ}c$ temperature and 55% relative humidity. 2. When sample was recycled through solar collector, the result of drying was 1/2 times more efficient than that of mat drying. 3. Average thermal efficiency of solar collector was 25% during the experimental period. 4. Browning extent was reduced to 1/2 times at heated air blow drying system using drying chamber.

• Agricultural and Biosystems Engineering
• /
• v.7 no.1
• /
• pp.1-7
• /
• 2006

A need exists to monitor and control the localized high temperatures often experienced in solar grain dryers, which result in grain cracking, reduced germination and loss of cooking quality. A verified finite element model would be a useful to monitor and control the drying process. This study examined the feasibility of the finite element method (FEM) to predict temperature distribution in solar grain dryers. To achieve this, an indirect solar grain dryer system was developed. It consisted of a solar collector, plenum and drying chambers, and an electric fan. The system was used to acquire the necessary input and output data for the finite element model. The input data comprised ambient and plenum chamber temperatures, prevailing wind velocities, thermal conductivities of air, grain and dryer wall, and node locations in the xy-plane. The outputs were temperature at the different nodes, and these were compared with measured values. The ${\pm}5%$ residual error interval employed in the analysis yielded an overall prediction performance level of 83.3% for temperature distribution in the dryer. Satisfactory prediction levels were also attained for the lateral (61.5-96.2%) and vertical (73.1-92.3%) directions of grain drying. These results demonstrate that it is feasible to use a two-dimensional (2-D) finite element model to predict temperature distribution in a grain solar dryer. Consequently, the method offers considerable advantage over experimental approaches as it reduces time requirements and the need for expensive measuring equipment, and it also yields relatively accurate results.

• Journal of Biosystems Engineering
• /
• v.2 no.2
• /
• pp.37-45
• /
• 1977

Solar energy is a potential source of power that offers much promise being used for low-temperature applications like drying farm crops, space heating, and water heating for domestic uses. Already much of it are being used for those purpose in foreign countries. However, very little research has been done to determine the possibility of using the solar energy in Korea. This study was conducted to develop the general prediction equation of the total radiation on a horizontal surface in Daejeon area based on 5 years 91972, Jun.1-1976. Dec.31) meteorological data (bright sunshine hours, average total horizontal radiation), and to obtain experimentally the thermal efficiency of solar air and water collectors, which will be used as a basic data of designing flat-plate solar collector system.In addition to the thermal efficiency of the collectorsthe relationship among those factors affecting it such as weather condition, orientation factor, and tilted angle of collector was analyzed. The results of this study were as follows. 1. The general predicted equation of the total radiation on a horizontal surface in Daejeon area based on bright sunshine hours was developed as $H_{av} =(1.546\frac{n}{N}-0.582)H_o$. Predicting the total radiation on a horizontal surface by the above equation was thought to be possible because to values of 0.882 was smaller than any t values at above 0.05 level on the basis of two tailed test of the difference between the calculated and the recorded values. 2.It was observed that optimum tilt angle of the collector in the summer and the autumn drying season was 13 degrees and 51 degrees respectively, these values could be obtained by adding or substracting approximately 25 degrees from the latitude of this area $(36.3^{\circ}N)$ .The relationship between orientation factor and declination of sun at suitable tilt angle of 33 degrees $(s=0.9\O)$ was shown at Fig.4. 3.The thermal efficiency of solar wdter collector was shown 13.4-51. 6% on Aug. 15 (the minimum radiation recorded) and 43.8 ~537% Aug.20 (the maximum radiation recorded), and 13.8~ 46.6 and 44.3~ 49.7 were shown on each corresponding day. 4.The thermal efficiency of the collectors according to the weather condition was shown a big difference of about 10% between the day of the maximum radiation recorded and the minimum, but the differen of efficiency between the air and the water collector was at most 2 ~ 3%. 5. Even if the efficiency of the solar water collector was a little higher than the solar air collector, for drying farm products, the solar air collector was thought to be more effective because the air heated by collector could be directly used for drying them.

• Solar Energy
• /
• v.7 no.2
• /
• pp.30-36
• /
• 1987

A shelf type solar dryer of simple design has been constructed and its performance evaluated by KIER (Korea Institute of Energy and Resources). Experimental result, the rate of moisture removal of the dried sguid in dryer is higher to that obtained by conventional sun drying. Design modification are suggest to improve its performance.

• Korean Journal of Food Science and Technology
• /
• v.16 no.1
• /
• pp.78-82
• /
• 1984

Effects of various drying conditions of agar gel on the physico-chemical properties of dried agar were investigated. For drying of the agar gel$(1.0{\times}1.0{\times}34.0cm)$ by means of sun drying, simple solar drying, hot-air drying ($30^{\circ}C$, control, natural convection), hot-air drying ($30^{\circ}C$, pretreatment, natural convection) and freeze drying, it took 96, 75, 67, 50 and 21 hours, respectively. The gel strengths of dried agar gel prepared by sun drying, solar drying, freeze drying and spray drying were320, 370, 270 and $360g/cm^2$, respectively and that of hot air-dried agar gel was influenced by drying temperature, pretreatment an mode of heat transfer. The gel strength, the gelation temperature and other quality index of spray-dried agar were not inferior to those of sun-dried agar, but it was not expected to be economical because of it recovery rate. In case of hot air drying, the gel strength value of agar increased as the drying rate increased. No significant differences among various products were noted in the gelation temperature, the melting temperature, the ash and $SO_3$ content.

• Solar Energy
• /
• v.20 no.2
• /
• pp.1-8
• /
• 2000

The present study has been conducted to offer geometrically optimal structure of a storage tank for a regenerator, one of the components of an open-type dehumidifying and drying system using solar energy to develop an alternatives for time-limited energy such as a fossil fuel, and to decrease an environmental pollutant. Two kinds of model classified by the mixing process were suggested to estimate the amount of regeneration rate. One was the stratified-type, "case 1", a method to place an entrance in the upper part of the tank and an outlet in the lower part. The other was the mixed-type, "case 2", a method to place vice versa. Solution temperature and concentration were used to evaluate the regeneration rate. As a result, the regeneration rate was better in "case 2".

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
• /
• v.16 no.1
• /
• pp.25-33
• /
• 1987

• Proceedings of the Korean Professional Engineer Association Conference
• /
• 1982.12a
• /
• pp.60-63
• /
• 1982

• Solar Energy
• /
• v.7 no.2
• /
• pp.54-64
• /
• 1987

Experiments on honeycomb structure collectors (HSC with/without cover) were performed and the experimental results showed good agreement with the preceding analytical results. The tendency of the efficiency of HSC was same with that of conventional air-type solar collector, even though there were some seasonal differences. Therefore, HSC, which can be itself utilized as a part of building structure, is applicable to space heating as well as preheating of industrial process and drying.