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Busan, South Korea

Kwon Y.,EcoEnergy Research Institute | Lee K.,EcoEnergy Research Institute | Park M.,EcoEnergy Research Institute | Koo K.,EcoEnergy Research Institute | And 5 more authors.
Journal of Nanoscience and Nanotechnology | Year: 2013

An experimental investigation on the characteristics of the convective heat transfer in the fully developing region of a circular straight tube with a constant heat flux was carried out with Al2O3 nanofluids. Stable nanofluids, which were water-based suspensions of Al2O3 nanoparticles, were prepared by two-step method. The effects of the thermal conductivity, viscosity, and heat capacity of the nanofluids on convective heat transfer were investigated. The result showed that the coefficient enhancement of the convective heat transfer in the Al2O3 nanofluids was increased with increasing fluid temperature compared to that of water at a volume fraction of 3.0% in the turbulent flow region. Thermal conductivity was increased from 8% to 20%, and the increment of convective heat transfer coefficient was enhanced from 14% to 30% with fluid temperature from 22 °C to 75 °C, respectively. We observed that the increment of convective heat transfer coefficient in nanofluids was much higher than that of the thermal conductivity at a given temperature condition. The enhancement of Brownian motion due to the decreasing kinematic viscosity led to a higher convective heat transfer coefficient at a higher temperature condition. Copyright © 2013 American Scientific Publishers. Source


Park C.,Pusan National University | Hwang Y.,Pusan National University | Lee J.,EcoEnergy Research Institute | Ahn Y.,Pusan National University
Particulate Science and Technology | Year: 2011

Tobacco smoke is one of the most common manmade aerosols. Yellow sand dust and pollen are the particular and regional pollutants generated by natural phenomena. These pollutants have different removal characteristics, respectively, when the air cleaning system is operated. It is well known that tobacco smoke particles are removed effectively with electrostatic precipitators. But it is necessary to evaluate whether the plasma air cleaning system has good performance of removing Yellow sand dusts and pollens simultaneously and also to establish the operation modes for efficient removal of those particular air pollutants by controlling the air flow rates passing the electrostatic precipitator and operating times of air cleaning system. In this study, the performance evaluation of plasma air cleaning systems is investigated with tobacco smoke particles, Yellow sand dusts, and pollens. For the multi-pass test in occupied spaces of 150 m3, the operation time required to reduce dust concentration from the initial concentration of 300 μg/m3 to 150 μg/m3, the criteria of indoor air quality in Korea, are 40 min for tobacco smoke, 28 min for Yellow sand dust, and 5 min for pollen when the flow rate is 17 m3/min. Also, the optimal operation modes for each pollutant are suggested for the efficient removal of indoor air pollutants. At first, most particles are removed by maximum flow operation. Second, the rest of the particles are removed by medium flow operation. Next, the plasma air cleaning systems are maintained by minimum flow for tobacco smoke mode and by repeating minimum flow and medium flow for Yellow sand and pollen modes. Edit to "Because the Yellow sand dust and the pollen flow into the room continuously and settle down ...noise reduction." Because the Yellow sand dust and the pollen flow into the room continuously and settle down. The plasma air cleaning system is suitable for the removal of the tobacco smoke, the Yellow sand dust, and the pollen for maintaining suitable indoor air quality, and, if it is operated through the suitable operation mode, energy efficiency will improve noise reduction. Copyright © Taylor & Francis Group, LLC. Source


Do Y.,LG Corp | Kim M.,LG Corp | Kim T.,LG Corp | Jeong S.,LG Corp | And 6 more authors.
Korean Journal of Chemical Engineering | Year: 2013

The performance of energy consumption in the closed-loop tumbler dryer with a condenser for clothes drying is evaluated as a function of the heater capacity, the drying air flow rate inside the dryer, and the cooling air flow rate. The clothes dryer in laundries used in this study consists of a tumbling drum, condenser for condensing the humid and hot air flowing out the rotating drums, and electric heater for heating the circulating drying air. Tests were performed at the heating capacity of 1.9 kW to 2.7 kW, the drying air flow rate of 60 m3/h to 140 m3/h, and the cooling air flow rate of 100 m3/h to 240 m3/h. The total energy consumption, the drying time, and the condensate water rate were also investigated. Parametric results showed that a larger heater power resulted in shorter drying time. With increasing heater power, the air temperature and the condensate rate increased due to the higher humidity ratio in the air. The drying air flow rate and the cooling air flow rate did not have a significant effect on drying performance. © 2013 Korean Institute of Chemical Engineers, Seoul, Korea. Source


Jung S.,Pusan National University | Ahn Y.,Pusan National University | Lee Y.,Pusan National University | Lee J.,EcoEnergy Research Institute
Korean Journal of Chemical Engineering | Year: 2013

The objective of this study is to analyze the removal characteristics and distribution of indoor air pollutants by a room air cleaner. A pollutant removal effect according to room volume and measurement point was evaluated in an indoor room. A series of filtration efficiency tests were performed on only the electrostatic precipitator of the room air cleaner. The measurements of filter efficiency and pressure drop across the electrostatic precipitator were made using an ASHRAE 52. 1-1992 filter test system and an opacity meter to measure the particle concentration upstream and downstream of the test filter. Also the performance of the air cleaner in the room was evaluated by examining tobacco smoke particle concentration. The size distribution of the tobacco smoke particles was 1. 27 μm in mass median diameter and a geometric standard deviation of 1. 313 μm. The efficiency of the electrostatic filter was measured as 78. 6% with dust particles of 1. 96 μm in mass median diameter and 1. 5m/s face velocity. The tobacco smoke particle concentration as a function of time decayed exponentially. The contaminant removal effect was increased when increasing the effective clean air exchange rate (ηQ/V), which is 0. 0780 min-1 for 51 m3 room and 0. 0235 min-1 for 149 m3 room. This study clearly shows that a room air cleaner with an electrostatic precipitator is effective in removing tobacco smoke particles. The removal characteristics and distribution of indoor air pollutants in other rooms is predicted based on empirical modeling. © 2012 Korean Institute of Chemical Engineers, Seoul, Korea. Source


Park S.,LG Corp | Hyun O.,LG Corp | Cho M.,LG Corp | Bae H.,LG Corp | And 6 more authors.
Particulate Science and Technology | Year: 2013

Yellow sand dust (Asian dust storm) causes harmful damage to both indoor and outdoor environments during the springtime. Removal of Yellow sand dust has become an issue for suitable indoor conditions, and an air cleaner is required to remove it efficiently; thus, an analysis of its characteristics should be conducted. In this article, two types of plasma air cleaning systems based on the principle of electrostatic precipitation are evaluated using equivalent dust to Yellow sand dust. To study the influence of an electrode shape of precharger on the collection efficiency, we carried out experiments using a plate and an ion impactor type electrode. From the results, the discharge current was found to be higher for the ion impactor electrode than for the plate electrode. Also, the collection efficiency was greater with the ion impactor electrode than with the plate electrode. For the single-pass test, the removal efficiencies of Yellow sand equivalent dust at the face velocity of 1.0m=s are greater than 80% with the plate and ion impactor electrodes. For the multi-pass test in occupied spaces, the operation time required to reduce Yellow sand dust concentration from the initial concentration of 300-150 mg=m3 (the criteria of indoor air quality), is 5 min for the ion impactor electrode and 7 min for the plate electrode. Also, the clean air delivery rate (CADR) value is 113 for the ion impactor electrode and 85 for the plate electrode. The plasma air cleaning systems are suitable for the removal of Yellow sand dust for maintaining suitable indoor air quality. Copyright © 2013 Taylor & Francis Group, LLC. Source

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