• Journal of Mushroom
• /
• v.15 no.1
• /
• pp.14-20
• /
• 2017

The oyster mushroom cultivation house typically has multiple layers of growing shelves that cause the disturbance of air circulation inside the mushroom house. Due to this instability in the internal environment, growth distinction occurs according to the area of the growing shelves. It is known that minimal air circulation around the mushroom cap facilitates the metabolism of mushrooms and improves their quality. For the purpose of this study, a CFD analysis FLUENT R16 has been carried out to improve the internal environment uniformity of the oyster mushroom cultivation house. It is found that installing a section of the working passage towards the ceiling is to maintain the internal environment uniformity of the oyster mushroom cultivation house. When all the environment control equipment - including a unit cooler, an inlet fan, an outlet fan, an air circulation fan, and a humidifier - were operated simultaneously, the reported Root Mean Square (RMS) valuation the growing shelves were as follows: velocity 23.86%, temperature 6.08%, and humidity 2.72%. However, when only a unit cooler and an air circulation fan operated, improved RMS values on the growing shelves were reported as follows: velocity 23.54%, temperature 0.51%, and humidity 0.41%. Therefore, in order to maintain the internal environment uniformity of the mushroom cultivation house, it is essential to reduce the overall operating time of the inlet fan, outlet fan, and humidifier, while simultaneously appropriately manage the internal environment by using a unit cooler and an air circulation fan.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.4
• /
• pp.2415-2423
• /
• 2015

Experiments were conducted on sine wave fin-and-tube heat exchangers having oval tubes under wet condition. Oval tubes having an aspect ratio of 0.6 were made, by deforming 12.7mm round tubes. Twelve samples, having different fin pitch and tube row, were tested. Results showed that, for oval tube samples, the effect of fin pitch on j and f factor was not significant. As for the effect of tube row, the lowest j factor was obtained for one row configuration(81% of two row configuration), which is clear contrast to round tube samples, where the highest j factor was obtained for one row configuration. Possible reasoning is provided considering the flow and heat transfer characteristics of sine wave channel combined with connecting oval tubes. Comparison of $j/f^{1/3}$ with plain fin-and-tube heat exchanger having 15.9mm O.D. round tube reveals that present oval fin-and-tube heat exchanger shows superior thermal performance except for one row configuration. In other words, $j/f^{1/3}$ of the two row oval tube heat exchanger was 1.6~2.5 times larger than those of round tube heat exchanger, 1.4~2.4 times larger for three row configuration and 1.2~2.8 times for four row configuration.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.38 no.12
• /
• pp.1009-1015
• /
• 2014

The present study investigated the effects of non-equilibrium condensation with the angle of attack on the coefficients of pressure, lift, and drag in the transonic 2-D flow of NACA0012 by numerical analysis of the total variation diminishing (TVD) scheme. At $T_0=298k$ and ${\alpha}=3^{\circ}$, the lift coefficients for $M_{\infty}=0.78$ and 0.81 decreased monotonically with increasing ${\Phi}_0$. In contrast, for $M_{\infty}$ corresponding to the Mach number of the force break, $C_L$ increased with ${\Phi}_0$. For ${\alpha}=3^{\circ}$ and ${\Phi}_0=0%$, $C_D$ increased markedly as $M_{\infty}$ increased. However, at ${\Phi}_0=60%$ and ${\alpha}=3^{\circ}$, which corresponded to the case of the condensation having a large influence, $C_D$ increased slightly as $M_{\infty}$ increased. The decrease in profile drag by non-equilibrium condensation grew as the angle of attack and stagnation relative humidity increased for the same free stream transonic Mach number. At ${\Phi}_0=0%$, the coefficient of the wave drag increased with the attack angle and free stream Mach number. When ${\Phi}_0$ > 50%, the coefficient of the wave drag decreased as ${\alpha}$ and $M_{\infty}$ increased. Lowering ${\Phi}_0$ and increasing $M_{\infty}$ increased the maximum Mach number.

• Korean Journal of Plant Resources
• /
• v.23 no.4
• /
• pp.379-385
• /
• 2010

This study was carried out to develop cultivation techniques of Climacium japonicum in transparent pot. We analyzed effect of different soil moisture content, air exposure degree, bed soil and ground cover moss on the growth of Climacium japonicum. The best humidity condition in transparent pot culture was 60~80% and a mixture of bed soil with peatmoss : perlite as 7:3 ratio was effective to growth. Two holes(each diameter is 4 mm) in the cover were also effective to the growth and control moisture in the transparent pot. The best mixture of bed soil was moss with peatmoss : pelite(7:3) in the pot culture but price of moss is expensive, the moss treatment was not practical. Total of 10 moss species were selected as ground cover plant; Hypnum erectiusculum Sull. et Lesq., Thuidium kanedae Sak., Hypnum plumaeforme Wils., Trachycystis microphylla Lindb., Bryum argenteum Hedw., Hypnum oldhamii Jaeg., Funaria hygrometrica Hedw., Leucobryum glaucum Aongstr., Polytrichum commune Hedw. and Weissia controversa Hedw. The plant height of selected moss was smaller than that of Climacium japonicum so these moss were very effective to cover the ground.

• Journal of Bio-Environment Control
• /
• v.10 no.1
• /
• pp.10-14
• /
• 2001

The cooling effect of a fog cooling system has a close relationship to air flow and relative humidity in the greenhouse. From the VETH chart for cooling design, a cooling efficiency can be improved by means of increasing the air exchange rate and the amount of sprayed water. In the no shading experimental greenhouse by time control, when average air exchange rate was 0.77 times.min$^{-1}$ and spray water amount was 2,009g, inside temperature of the greenhouse was 31$^{\circ}C$ that was almost close to outside temperature and cooling efficiency was 82%. When average air exchange rate was close to temperature of the greenhouse that was no cooling and 70% shading greenhouse environment. When average air exchange rate was 2.59times.min$^{-1}$ , spray water amount was 2,009g and shading rate was 70%, inside relative humidity of the greenhouse was increased was 2,009 g and shading rate was 70%, inside relative humidity of the greenhouse was increased, but temperature was not decreased. When average air exchange rate was 2.33 times.min$^{-1}$ and spray water amount was 2,009g, inside temperature was 31.4 and at that time maximum wind speed at the air inlet of greenhouse was 1.9m.s$^{-1}$ . Since time controller sprayed amount of constant water at a given interval, some of sprayed water remained not to be evaporated, which increased relative humidity and decreased cooling efficiency. Because the shading screen prevented air flow in the greenhouse, it also caused the evaporation efficiency to be decreased. In order to increase cooling efficiency, it was necessary to study on controling by relative humidity and air circulation in the greenhouse.

• Journal of Bio-Environment Control
• /
• v.26 no.3
• /
• pp.188-193
• /
• 2017

The purpose of this study was to investigate the changes of environmental conditions and the quality and yield of melon fruit by heat fan operation in greenhouses at winter season. The average daily temperature inside the tunnels during January 1 to 31, 2017 was $0.9^{\circ}C$ higher than that of the control $17.8^{\circ}C$. The air flow rate of heater fan treatment was 4.8 times higher than the control (untreated $0.05m{\cdot}s^{-1}$) at 20cm above the ground where the korean melon grew. The temperature of the heater pan was $5.6^{\circ}C$ higher than that of the untreated at $35.3^{\circ}C$ and the relative humidity was 8.1% lower than that of the untreated at 39.1%. The flowering rate of the heater fan treatment was 96%, 5% higher than the control. The number of first harvest days of heater fan treatment was shortened by 4 days than that of untreated treatment. Fruit quality and marketable fruit yield increased by 3.4% and 38% compared to untreated respectively, the heater fan treatment increased the temperature inside the greenhouse and air flow rete, which were beneficial for growing the korean melon in greenhouses at winter season.