• Particle and aerosol research
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• v.5 no.4
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• pp.189-197
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• 2009

Wet-type particulate removal system is employed in most of ironmaking processes. These de-dusting systems require additional downstream aggregates for treatment of water and for drying of the collected slurry. Thus dried slurry can be pressed in shape of briquettes and recycled in the steelmaking process. Different from the wet-type, the dry-type particulate removal systems generate no slurry. A high-temperature, high-pressure de-dusting system with inertial inlet was developed. The target application of this system was to remove particulate matter generated from the novel ironmaking process and other steelmaking processes. In this study we conducted tests with this newly developed system to evaluate the performance of the silica-carbide (SiC) ceramic filters. In addition, for purpose of comparison, we also conducted tests with a unit which has conventional direct inlet. Fe-Particles collected from the novel ironmaking process were used in our tests as test dusts. The temperature and the pressure were kept constant at their respective values $800^{\circ}C$ and $3kg_f/cm^2$.

• Nuclear Engineering and Technology
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• v.55 no.8
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• pp.2757-2772
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• 2023

The fluid retention effect of the Volume Control Tank (VCT) leads to a long time delay in Reactor Coolant System (RCS) concentration during the boration process. A coupled model combining a lumped-parameter sub-model and a computational fluid dynamics sub-model is currently used to investigate the concentration dynamic characteristic of RCS during the boration process. This model is validated by comparison with experimental data, and the predicted results show excellent agreement with experimental data. We provide detailed fields in VCT and concentration variations of RCS to study the interaction between mixing in VCT and the transient responses of RCS. Moreover, the impacts of the inlet flow rate, inlet nozzle diameter, original concentration, and replenishing temperature of VCT on the RCS concentration characteristic are studied. The inlet flow rate and nozzle diameter of VCT remarkably affect the RCS concentration characteristic. Too-large or too-small inlet flow rates and nozzle diameters will lead to unacceptable long delays. In this work, the optimal inlet flow rate and nozzle diameter of VCT are 5 m³/h and 58.8 mm, respectively. Besides, the impacts of the original concentration and replenishing temperature of VCT are negligible under normal operating conditions.

• Journal of Bio-Environment Control
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• v.25 no.4
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• pp.270-276
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• 2016

This study analysed overall heat transfer coefficient, heat transmission, and rate of indoor air heating provided by water curtain in order to determine the heat transfer characteristic of double-layered greenhouse equipped with a water curtain system. The air temperatures between the inner and outer layers were determined by the water flow rate and inlet water temperature. Higher water flow rate and inlet water temperature resulted in the increased overall heat transfer coefficient between indoor greenhouse air and water curtain. However, it was found that with higher levels of water flow rate and inlet water temperature, indoor overall heat transfer coefficient was converged about $10W{\cdot}m^{-2}{\cdot}^oC^{-1}$. The low correlation of overall heat transfer coefficient between water curtain and air within double layers was likely because the combination of greenhouse shape, wind speed and outdoor air temperature as well as water curtain affected the heat transfer characteristics. As water flow rate and inlet water temperature increased, the heat transferred into the greenhouse by water curtain also tend to rise. However it was demonstrated that the rate of heat transmission from water curtain into greenhouse with water curtain system using underground water was accounted for 22% to 28% for total heat lost by water curtain. The results of this study which quantify heat transfer coefficient and net heat transfer from water curtain may be a good reference for economical design of water curtain system.

• Solar Energy
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• v.16 no.2
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• pp.65-77
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• 1996

The operating thermal chracteristics of direct contact liquid-ice heat exchanger was experimentally investigated. In this paper, The effects of Ice Packing Factor(IPF), the inlet temperature and the flow rate of Heat Transfer Fluid(HTF) were stuided in the liquid-ice heat exchanger. Thermal stratification in liquid-ice heat exchanger was established clearly and faster at the higher inlet temperature and flow rate of HTF. At the end of melting of the lower flow rate is cleared the thermal stratification in liquid-ice heat exchanger. The temperature stratification is long with higher value of IPF of liquid-ice heat exchanger. The mean temperature of liquid-ice storage was changed rapidly with increasing flow rate and inlet temperature of HTF. The gradiant of ratio of total energy to latent energy was found higher with increasing inlet temperature and flow rate.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.8
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• pp.541-546
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• 2008

A coolant operating condition in al fuel cell stack was an important factor to determine the temperature distribution which affected the fuel cell performance and relative humidity. In this study, the fuel cell performance was evaluated as a function of the coolant flow rate with the range of $0.1{\sim}0.8$ liter/min cell and the coolant inlet temperature of $20{\sim}82^{\circ}C$. The cell temperature increased with increasing the coolant inlet temperature and with decreasing the coolant flow rate. The coolant inlet temperature and flow rate to maintain the better performance of the fuel cell were in the range of $45{\sim}60^{\circ}C$ and $0.2{\sim}0.4$ liter/min cell, respectively. The experimental results showed that the optimal heat removal rate from the stack by coolant was $0.4{\sim}0.6W/cm^2$ cell.

• Journal of the Korean Society of Propulsion Engineers
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• v.3 no.4
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• pp.51-57
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• 1999

Temperature and velocity controlling of air at inlet position of Ramjet combustor is important under Ramjet engine grounding-test condition since temperature of inlet air increases due to compression process by supersonic flow at inlet position of Ramjet combustor. In this study, Vitiated Air Heater methodology was used to control temperature of air that is inducted into Ramjet combustor. Temperature and velocity of air at Vitiated air heater exit, which is inducted into Ramjet combustor, were measured to evaluate Vitiated air heater system developed in this study. It is shown that temperature and velocity of inducted air can be well controlled using Vitiated air heater system developed in this study, and we could make a Vitiated Air which is almost same with real air.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.6 s.237
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• pp.722-729
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• 2005

Design analysis of the solid oxide fuel cell and gas turbine combined power system is performed considering different methods for preheating cell inlet air. The purpose of air preheating is to keep the temperature difference between cell inlet and outlet within a practical design range thus to reduce thermal stress inside the cell. Three different methods considered are (1) adopting a burner in front of the cell, (2) adopting a preheater (heat transfer from the main combustor) in front of the cell and (3) using recirculation of the cathode exit gas. For each configuration, analyses are carried out for two values of allowable maximum cell temperature difference. Performance characteristics of all cases are compared and design limitations are discussed. Relaxation of the cell temperature difference (larger difference) is proved to ensure higher efficiency. Recirculation of the cathode exit gas exhibits better performance than other methods and this advantage becomes more prominent as the constraint of the cell temperature difference becomes more severe (smaller temperature difference).

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.5
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• pp.521-529
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• 2012

Since the energy demand for refrigeration and air-conditioning has greatly increased all over the world, thermally activated refrigeration cycle has attracted much attention. This study carries out a performance analysis of a vapor compression cycle (VCC) driven by organic Rankine cycle (ORC) utilizing low-temperature heat source in the form of sensible heat. The ORC is assumed to produce minimum net work which is required to drive the VCC without generating an excess electricity. Effects of important system parameters such as turbine inlet pressure, condensing temperature, and evaporating temperature on the system variables such as mass flow ratio, net work production, and coefficient of performance (COP) are thoroughly investigated. The effect of choice of working fluid on COP is also considered. Results show that net work production and COP increase with increasing turbine inlet pressure or decreasing condensing temperature. Out of the five kinds of organic fluids considered $C_4H_{10}$ gives a relatively high COP in the range of low turbine inlet pressure.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.4
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• pp.254-260
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• 2003

The boiling characteristics for R134a are studied to clarify the hysteresis at low temperature on enhanced tubes of a flooded evaporator. Initial boiling conditions, refrigerant temperature, and inlet temperature of the chilled water are considered as the key parameters of the experiments. Unlike previous studies of the boiling heat transfer with uniform heat flux and uniform wall temperature, the wall temperature was varied along the tube. In, this study, it was found that the hysteresis of the temperature overshoot (705) at the onset of nucleate boiling initially at the inlet section of the tube. It is also concluded that the abnormal operation can be avoided during the low temperature boiling if the refrigeration system is started with LMTD larger than $3.4^{\circ}C$ at initial stage and larger than $1.0^{\circ}C$ at normal stage.

• Solar Energy
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• v.18 no.1
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• pp.57-67
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• 1998

A study on a buoyancy effect by the temperature difference between a inner room air and a inflowing cool air and also by Inlet velocity can contribute greatly to enhance performance of air conditioning system, so the study on the distribution characteristics of inflowed cool air is important to analyze the cool air storage in a room. For this study, in the real-sized model room, the temperature differences between inflowing cool air and inner room air are 10, 20, $30^{\circ}C$, and the inlet velocities of inflowing cool air are 1, 2, 3m/s respectively as dynamic parameters. Also, a anemos and a vane type diffuser are used as inlet geometric conditions. Following conclusions have been obtained through this study. 1) In case of the anemos type diffuser, it is found that a dimensionless temperature profile is low and the distribution of the inflowed cool air is uniform. and also, all diffuusers have a low temperature of the inner room as increasing the inlet velocity. 2) A mixing takes place rapidly in case of the anemos type diffuser when the temperature difference is low ${\Delta}T=10^{\circ}C$ and the inletvelocity is high V=3m/s. and the mixing degree is higher with the anemos type diffuser than the vane.