• 한국전산유체공학회:학술대회논문집
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• 1996.05a
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• pp.125-130
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• 1996

A numerical analysis is conducted on heat transfer and fluid flow of a plasma spraying process under the DC-RE hybrid electromagnetic field. Plasma flow is analyzed by using Eulerian approach and the equation of particle motion is simultaneously solved using a trajectory analysis with a lumped-heat-capacity model. Axisymmetric two dimensional electromagnetic fields governed by Maxwell's equations are solved based on a vector potential concept. The effects of the RF electromagnetic field on the temperature and velocity fields of the turbulent plasma flow are clarified. Control characteristics of phase changes and dispersed features of particles by applying the RF electromagnetic field are also clarified in an attempt to improve the plasma spraying process

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.2
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• pp.175-183
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• 2004

Performance of the water/air direct contact air conditioning system, in which heat and mass are directly transferred between air and water droplet, is simulated using semi-empirical method. Direct contact system improves transport efficiency compared to conventional indirect contact system. In this study, correlations for h$_{c}$A / c$_{pm}$ which represent the capacity of direct contact system are derived as a function of air and water flowrate from the experimental data. Cooling and heating performance of the water/air direct contact air conditioning system are evaluated using these correlations.ons.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1221-1226
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• 2008

Present, the cooling method of using a phase-change heat transfer such as immersed type, heat pipe etc is applied in cooling of high-capacity power semiconductors of the main power system for the high speed train with the concentrated traction. In order to apply these phase-change cooling system to the high speed EMU to be developed, needed are technological researches of consideration of installing space, air passage, light weight material and miniaturization. Although this research establishes design specifications through theoretical analysis and computational analysis from the basic design process of the cooling system of the propulsion system for the high-speed EMU, when details design is completed, present improvement subject and optimum design before manufacturing the prototype of the cooling system on the basis of analysis results. And then, carried out will be the performance tests through prototype manufacture and reliability estimation by components of cooling system.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.3 s.246
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• pp.246-254
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• 2006

The present study shows the experimental and modeling results of the cooling system using nanofludic loop thermosyphon. the experimental results show that nanofluid is not effective for small scale cooling system. The heat transfer performance is not much improved with the current small scale loop system comparing with the convectional water based loop system. In this study, various effects of nanofluids such as the concentration, the md of particle, host fluid, and heat capacity and so on were investigated. With nanofluid as the working fluid, the flow instability was improved at a certain concentration.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.5
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• pp.715-724
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• 2022

In many electric vehicles, large-capacity pouch-type lithium-ion battery packs are mainly used to increase the mileage on a single charge. The lithium ion battery should be operated within the temperature range of 25℃ to 40℃ because the battery performance can be rapidly deteriorated due to an increase in internal temperature. Battery thermal management system (BTMS) can give the suitable temperature conditions to battery by water cooling method. In this research, the heat transfer characteristics (the battery temperature distributions and the water flow characteristics) were analyzed by CFD method to investigate the thermal performance of the cooling plate with 4-pass water flow structure. Moreover, the effect of the presence of fins between the battery cell was identified. The fins made smooth temperature distributions between the battery cells due to the heat spreading and lower the average battery cells temperature.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.10
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• pp.1347-1354
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• 1999

Recently, the markets of the air conditioner are enlarging. The market size will reach 2.0 billion won in 2000. Electric heat pumps have been utilized as main residential air conditioners. especially in Korea. They cause a surge up electric power demand during summer. Moreover, the use of HCFCs and HFCs causes serious problem to the global environment such as global warming and ozone layer destruction. Absorption chiller and heater could solve such problems. It was built and tested for analyzing the performance of the generator for absorption chiller and heater. Experiment was done with a high temperature generator, a low temperature generator, heat exchangers, a condenser and a solution tank. It was tested that the double effect series flow cycle with two kinds of solution cycle. Solution cycle B showed better than solution cycle A. Two kinds of heat exchanger were used, where one's heat transfer area is bigger than the other. Bigger one increased a little performance of absorption chiller and heater. But it was not economical. From this study, we got that the coefficient of performance(COP) is 0.82 and the capacity is 7.24 kW for an absorption chiller and heater.

• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.74-79
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• 2011

This study was accomplished to evaluate the performance of Multi Effect Distillation(MED) for solar thermal desalination system. It was designed Multi effect distillation with $3m^3/day$ capacity and Shell&Tube type heat exchanger. Also, The effective heat transfer of Shell&Tube heat exchanger was used Cu(90%)-Ni(10%) corrugated tube. The parameters relating to the performance of Multi Effect Distillation are known as hot water flow rate. The experimental conditions for each parameters were $18^{\circ}C$ for sea water inlet temperature, $6m^3/hour$ sea water inlet volume flow rate, $75^{\circ}C$ for hot water inlet temperature, 2.4, 3.6, and $4.8m^3/hour$ for hot water inlet volume flow rate, respectively. The results are as follows, Development for Multi effect distillation was required about 40kW heat and 35kW cooling source to produce $3m^3/day$ of fresh water. And, Performance ratio of Development Multi effect distillation was about 2.0191.

• Journal of the Korean Solar Energy Society
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• v.31 no.1
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• pp.1-7
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• 2011

This study was accomplished to evaluate the performance of Multi Effect Distillation(MED) for solar thermal desalination system. It was designed Multi effect distillation with $3m^3$/day capacity and Shell&Tube type heat exchanger. Also, The effective heat transfer of Shell&Tube heat exchanger was used Cu(90%)-Ni(10%) corrugated tube. The parameters relating to the performance of Multi Effect Distillation are known as hot water flow rate. The experimental conditions for each parameters were $18^{\circ}C$ for sea water inlet temperature, $6m^3$/hour sea water inlet volume flow rate, $75^{\circ}C$ for hot water inlet temperature, 2.4, 3.6, and $4.8\;m^3$/hour for hot water inlet volume flow rate, respectively. The results are as follows, Development for Multi effect distillation was required about 40kW heat and 35kW cooling source to produce $3m^3$/day of fresh water. Based on the results of this study, It makes possible to secure economics of desalination system with solar energy which is basically needed development of high efficiency fresh water generator.

• Journal of the Korean Solar Energy Society
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• v.29 no.3
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• pp.45-50
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• 2009

To estimate the operating performances of the geothermal heat exchange pipe(GHEX), GHEXs of 400RT geothermal system were measured and analyzed through a year. The followings are the results. The temperature of 2 GHEXs installed 4m apart was fluctuated very similarly. When the geothermal system is nor operating or is operating as heating mode, the temperature of G.L.-170m was always higher than G.L.-70m's. But it reversed when the geothermal system is operating as cooling mode. And through a year, it has been observed that the temperature of G.L.-170m is increased approximately $1.5^{\circ}C$. With previously mentioned results, the heat transfer capacity of G.L.-70m's geological stratum is estimated as higher than that of the G.L.-170m.

• International Journal of Highway Engineering
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• v.18 no.2
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• pp.73-82
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• 2016

PURPOSES: The national highways and expressways in Korea constitute a total length of 17,951 km. Of this total length of pavement, the asphalt pavement has significantly deteriorated, having been in service for over 10 years. Currently, hot in-place recycling (HIR) is used as the rehabilitation method for the distressed asphalt pavement. The deteriorated pavement becomes over-heated, however, owing to uncontrolled heating capacity during the pre-heating process of HIR in the field. METHODS: In order to determine the appropriate heating method and capacity of the pre-heater at the HIR process, the heating temperature of asphalt pavement is numerically simulated with the finite element software ABAQUS. Furthermore, the heating transfer effects are simulated in order to determine the inner temperature as a function of the heating system (IR and wire). This temperature is ascertained at $300^{\circ}C$, $400^{\circ}C$, $500^{\circ}C$, $600^{\circ}C$, $700^{\circ}C$, and $800^{\circ}C$ from a slab asphalt specimen prepared in the laboratory. The inner temperature of this specimen is measured at the surface and five different depths (1 cm, 2 cm, 3 cm, 4 cm, and 5 cm) by using a data logger. RESULTS: The numerical simulation results of the asphalt pavement heating temperature indicate that this temperature is extremely sensitive to increases in the heating temperature. Moreover, after 10 min of heating, the pavement temperature is 36%~38% and 8%~10% of the target temperature at depths of 25 mm and 50 mm, respectively, from the surface. Therefore, in order to achieve the target temperature at a depth of 50 mm in the slab asphalt specimen, greater heating is required of the IR system compared to that of the gas. CONCLUSIONS : Numerical simulation, via the finite element method, can be readily used to analyze the appropriate heating method and theoretical basis of the HIR method. The IR system would provide the best heating method and capacity of HIR heating processes in the field.