• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.489-495
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• 2003

A high performance and low noise refrigerator fan has been developed in order to satisfy the customer's high quality needs, that is, luxury, big size and low noise. In this study, the characteristics of a new developed fan and a current fan was calculated and compared by using numerical simulation. Rotation of a fan makes cold air circulation inside a refrigerator. A numerical simulation of air flow shows distribution and local flow regime of a cold air flow circulation, and revealed a cause of low noise as well. Optimization of a duct shape also decreased noise level.

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

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.170-174
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• 2001

In this paper, CFD technique has been used at design stage to predict space air distribution in a cycle stadium with air circulation system. An air circulation flow of 0.67 rev./min was observed at computed results in the stadium space with and without air circulation system. Comparing the thermal comfort of the two models with or without air circulation system showed that the thermal environment in the former was superior in the latter. Energy savings could be achieved for the model with air circulation due to its lower air inflow temperature.

• Korean Journal of Agricultural Science
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• v.41 no.4
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• pp.461-472
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• 2014

This study was conducted to build the CFD simulation model which can quantify the distribution of the meteorological factors in air-heated greenhouse for chrysanthemum according to the location and capacity of air-circulation fan. The CFD model was also verified by experiment. It was judged that SST model was the most appropriate turbulence model which can properly describe the airflow by the air-circulation fan. According to the simulation results, the differences between the measured and predicted temperatures from 18 points at each height in the greenhouse were $0.2{\sim}0.4^{\circ}C$ in average. This showed a good agreement between the predicted data and the measured ones. The developed CFD model can be a useful tool to evaluate and design the air-circulation systems in the greenhouse with various configurations.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.10
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• pp.982-992
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• 2001

In this paper, the performance of ventilation equipments in enclosed parking garages were investigated for several air distribution systems by numerical method. Air change effectiveness of the non-mixing system was 0.42. It meant that more supply air as much as the design supply air was needed to maintain good indoor air quality. In the high speed nozzle ventilating system which is most expensive one, air change effectiveness was 0.54. Therefore this system satisfied to ventilation design. In the jet fan ventilating systems, air change effectiveness for jet fan ventilating system-A with 18 jet fans and jet fan ventilating system-B with 6 jet fans in circulation mixing arrangement were 0.565 and 0.42 respectively. Jet fan ventilating system-C with 6 jet fans in transport mixing arrangement was 0.535. Jet fan ventilating system-A and jet fan ventilating system-C met the ventilation design. But velocity in jet fan ventilating system-A was over 2.0m/s which is inappropriate in human comfort. Therefore this system is not proper to ventilation. Jet fan ventilating system-C was the optimum one for enclosed parking garages among 5 systems examined in this paper.

• Journal of the Korean Society of Clothing and Textiles
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• v.33 no.11
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• pp.1806-1816
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• 2009

This study analyzes the efficiency of a solar cell attached to an air circulation jacket. A commercially available silicon solar panel was selected and attached at four spots where the body angle was $40-60^{\circ}$ and voltage ($V_{oc}$, V), current ($I_{sc}$, A), and output power (P, W) were measured to determine the efficiency. The solar panel was applied to the outer jacket that operates with two fans to increase the convection that lowers the body temperature. The heavy work of standing, walking, and sweeping of a street sweeper was simulated in the field test. The microclimate within the jacket (with or without a fan) was measured and the subjective thermal, humidity, and comfort sensations were surveyed. SPSS 12.0 statistical package was used for a t-test and Wilcoxon signed-rank test. The results show that the highest efficiency of the solar cell was at the incident angle of $60^{\circ}$ in terms of voltage, current and output power distribution. The microclimate temperature of the air circulation jacket decreased significantly with the high power of the fan and subjects felt cooler than the jacket with a fan at the incident angle of $60^{\circ}$. Air circulation jackets operated by a silicon solar panel showed a significant cooling effect on the wearers.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.6
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• pp.581-588
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• 2000

This paper describes the effect of vertical air circulation on the thermal environment in an airport passenger terminal with induced flow by jet fans. In comparing the level of thermal comfort at the breathing line of 1.5 m in height, the results from the two models with or without the vertical air circulation, show that the average PPD is 8% in the former and 23% in the latter, respectively. It is thought that vertical air circulation lends to improved thermal comfort for human in respect of ventilation in a large space.

• Journal of Bio-Environment Control
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• v.16 no.4
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• pp.291-296
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• 2007

This study was conducted to investigate the effects of horizontal air flow produced by circulation fans on horizontal and vertical profiles of meteorological factors. The three-dimensional distributions of air speed, air temperature, relative humidity and carbon dioxide $(CO_2)$ concentration were measured with and without the fans in operation. The uniformity of the spatial distribution of meteorological factors decreased as the outside air temperature decreased. In "fans off" condition, spatial variations of $4.7^{\circ}C$ in air temperature, 19% in relative humidity were detected. When the fans were operated, these variations were reduced to 2.2 and 6.3%, respectively. As the fan capacity increased, the difference in air temperature among sampling points decreased. The fan capacity of $0.0104m^3{\cdot}s^{-1}{\cdot}m^{-2}$ was enough to obtain a reasonable air flow in greenhouse. The vertical profiles of air temperature and $CO_2$ concentration were reasonably uniform regardless of measurement height and fan capacity. Further researches on the position of fans to reduce the difference in air temperature along the width and the effects of using a larger number of smaller fans are required.

• Journal of computational fluids engineering
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• v.19 no.4
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• pp.80-85
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• 2014

High-volume low-speed (HVLS) fans are one category of ceiling fan installed in large enclosings such as warehouses, large barns and health clubs in order to generate comfortable air circulation. As a rotary blade, aerodynamic performance of a HVLS fan is predominantly related to its airfoil(s), and the pitch and twist angles. This paper first, investigates the effects of airfoil on the performances of three different HVLS fans with NACA 5414, 6413 and 7415 airfoils. The fans have six untwisted blades with the diameter of 6 m and rotate at 60 RPM. The blades pitch angels are $12^{\circ}$, $12^{\circ}$ and $13^{\circ}$, respectively. The results are presented in the form of the aerodynamic forces and moments, volumetric flow rate and streamlines. Regarding the volumetric flow of air, the results show that the model with NACA 7415 has the best performance. Hence, two other HVLS fans with the same airfoil but, with four and five blades are studied in order to investigate the effects of number of blades. From the point of view of air circulation still the six-bladed fan is the best one; however, the five-bladed fan is more efficient in power consumption.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.250-254
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• 1998

This paper shows how the environmental parameters(temperature, humidity) in the greenhouse are influenced by air movement produced by air circulation fans. When the fans were used, they could make indoor temperature and humidity homogenious, but there was no significant difference in the location and number of fans. When the fans were not used during the night time, there was no significant difference in the temperature and humidity, but the standard deviation was reduced by using the fans.