• Proceedings of the Korea Society of Poultry Science Conference
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• 2002.11a
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• pp.108-109
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• 2002

The study was carried out to iind out the suitable ventilation system of the broiler house in winter season in Korea. Ammonia (NH$_3$-N) gas concentration (4.2ppm) of the system of pipe air inlet-forced chimney outlet was lower than that of the system of side wall inlet. The growth performance of broilers in the house equiped with pipe air inlet-chimney exhaust was higher than that of other ventilation systmes in which the average daily gain, feed efficiency and heat cost per head in the system of pipe air inlet-forced chimney excretion were 45.6g, 1.71 and 35.4 won per head, respectively. When the lengths of pipe air inlets were compared, the wind speed from the 4 meter-inlet was highest. The temperature of the broiler house equipped with the pipe air inlet system was higher (5.9 ∼ 7.7$^{\circ}C$) than that of the curtains in side wall Inlet system, in which the pipe air inlet system expects the lower heat cost.

• Journal of Mechanical Science and Technology
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• v.16 no.5
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• pp.696-702
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• 2002

In the present paper, the effects of inlet pressure on the heat and mass transfer rates of an air cooler are numerically predicted by a local analysis method. The pressures of the moist air vary from 2 to 4 bars. The psychrometric properties such as dew point temperature, relative humidity and humidity ratio are employed to treat the condensing water vapor in the moist air when the surface temperatures are dropped below the dew point. The effects of the inlet pressures on the heat transfer rate, the dew point temperature, the rate of condensed water, the outlet temperature of air and cooling water are calculated. The condensation process of water vapor is discussed in detail. The results of present calculations are compared with the test data and shows good agreements.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.4_2
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• pp.467-474
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• 2021

The renewable energy is known as eco-friendly energy to reduce the use of fossil fuel and decrease the environmental pollution due to exhaust gas. Targets of solar collector in domestic are usually acquisitions of hot water and hot air. System of air-heating collector is one of the technologies for obtaining hot air in cases of especially heating room and drying agricultural product. The purpose of this study is to investigate the characteristics of thermal flow such as relative pressure, velocity, outlet temperature and buoyancy effect in air-heating collector using solar heat. The flow field of air-heating collector was simulated using ANSYS-CFX program and the behaviour of hot air was evaluated with SST turbulence model. As the results, The streamline in air-heating collector showed several circular shapes in case of condition of buoyancy. Temperature difference in cross section of outlet of air-heating collector did not almost show in cases of buoyancy and small inlet velocity. Furthermore merit of air-heating collector was not observed in cases of inlet velocities. Even though it was useful to select condition of buoyancy for obtaining high temperature, however, it was confirmed that the trade off between high temperature of room and rapid injection of hot air to room could be needed through this numerical analysis.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.2
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• pp.422-429
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• 1990

The experimental study investigates two aspects of counterflow sensible heat regenerator operation. First, it examines the regenerator performance in periodic steady state operation with spatially nonuniform inlet temperature in one of the fluid stream. Second, the study examines the transient response of a regenerator to a step change in the inlet temperature of one of the fluid streams. The effect of transient inlet temperatures is analyzed in terms of the response of the outlet fluid temperatures to a step change in temperature of one of the inlet fluid streams. The effect of temperature nonuniformities is analyzed in terms of the change of temperature nonuniformities is analyzed in terms of the change in steady state effectiveness due to a circumferential temperature distribution in one of the inlet fluid streams. an experimental analysis has been conducted using a counterflow, parallel passage, and rotary regenerator made from polyethylene film. Efficiencies follow similar trends with increasing matrix to fluid capacity rate ratio for the balanced and symmetric regenerator with nonuniform inlet temperature.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.271-274
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• 2007

In the fuel of the solid fuel ramjet there are metal particles in order to improve the Isp like as solid rocket propellants. Because of the short combustion residence time these metallized fuels have low combustion efficiencies. Therefore it is necessary to increase the combustion efficiency and the inlet air temperature does an important role to this. The main factors to affect the inlet air temperature is the free stream temperature and the flight Mach number. Also the flow velocity in the combustor does an important role, therefore entire range of the air flow; from the stagnation to the sonic velocity in the ramjet combustor is considered.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.2
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• pp.79-84
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• 2013

In this study, a cold aisle containment system was proposed among various strategies to reduce the energy waste by recirculation air from the hot aisle. To verify the effectiveness of the cold aisle containment system, a test bed which is similar to an actually existing server room was set up in the Internet Data Center(IDC) building. Comparative experiments, conventional open type cooling system and cold aisle containment system were carried out under actual conditions. The result revealed that the range of inlet temperature of the server system was $20{\sim}25^{\circ}C$ in an existing cooling system and the range of inlet temperature dropped below $20^{\circ}C$ by the cold aisle containment system. After all, cold aisle containment system was proved to be the solution for energy saving cooling system.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.629-632
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• 2009

The polymeric desiccant rotor is made from the super absorbent polymer by ion modification. The moisture sorption capacity of the super desiccant polymer(SDP) is 4 to 5 times larger than those of common desiccant meterials such as silica gel or zeolite. It is also known that SDP can be regenerated even at the relatively low temperature. To fabricate the desiccant rotor, firstly the SDP was laminated by coating the SDP on polyethylene sheet. Then corrugated and rolled up into a rotor. The diameter, the depth, the dimensions of the corrugated channel, etc. were pre-determined from numerical simulation on the heat and mass transfer in the desiccant rotor. The dehumidification performance was tested in a climate chamber. The relevant tests were carried out at the process air inlet temperature of $32^{\circ}C$, the regeneration air inlet temperature of $60^{\circ}C$ and the inlet dew-point temperature of both the process air and the regeneration air of $18.5^{\circ}C$, when the rotation period is long, the moisture sorption is not effective. In the desiccant rotor developed in this study, the optimum rotation period is found about 350s at the regeneration temperature of $60^{\circ}C$. It was found from further experiments that the optimum rotation tends to decreases as the regeneration temperature increases. Meanwhile, the outlet temperature of the process air deceases monotonically as the rotation period increases.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.732-740
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• 2019

Evaporative humidification using a humidifying element is widely used for humidification of a building or a data center. The performance of a humidifying element is commonly expressed as humidification efficiency, which is used independent of air temperature, humidity and water temperature. In this study, a series of tests were conducted at two air conditions (data center and commercial building) using two different humidifying elements (cellulose/PET and Glasdek) changing the frontal air velocity and water temperature. Results showed that the measured humidification efficiency was dependent on the air condition and water temperature. In fact, even dehumidification occurred at the inlet of the humidifying element at the air condition of commercial building. The reason was due to the inlet water temperature, which was lower than the dew point air temperature. As the difference between the inlet water and the dew point air temperature increased, the humidification efficiency decreased. This suggest that proper thermal model should account for the inlet region, where the amount of moisture transfer may be different from the other part of the humidification element. A simple analysis on the thermal performance of the cellulose/PET humidification element showed that the Sherwood number was adequately predicted, whereas the friction factor was ovepredicted, probably due to the simplification of the channel geometry and the neglection of the water film on the element surface.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.5
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• pp.561-569
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• 1999

The effects of longitudinal heat conduction on the performance of heat transfer surfaces are investigated by using a single-blow method. In the transient testing method for determining the heat transfer characteristics, exponential inlet temperature variations are made by using screen-mesh heater with small time constant and low frontal velocities of the test section, and the experimentally determined inlet temperature profile is used as the inlet fluid temperature condition. The effects of longitudinal heat conduction are negligible only if $\gamma^\act<0.05\;and \;N_{tu}\le3$ and should be considered if $N_{tu}\le3$ The test results ate compared with the existing theoretical and experimental data and the validity of this technique is confirmed by the good agreement.

• Journal of Biosystems Engineering
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• v.24 no.6
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• pp.513-522
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• 1999

This study was performed to get the optimal operating conditions of an water-air compact heat pump system using R-134a. The experiments was done for three elvels of the air mass flow rate and the compressor driving speed during air-heating process. The temperature of the air at the condenser inlet and outlet was 17~23$^{\circ}C$, 36~44$^{\circ}C$, respectively. The average temperature of the refrigerant at the evaporator and condenser was 1$0^{\circ}C$, 6$0^{\circ}C$, respectively. The temperature of the refrigerant was not depending on the air mass flow rate and the compressor driving speed. The pressure of the refrigerant at the condenser inlet and outlet was ranged of 10~18.5kg/$\textrm{cm}^2$ and that at the evaporator was ranged of 3.1~3.3kg/$\textrm{cm}^2$. The pressure drop at the condenser and evaporator was about 1.5, 1.2 kg/$\textrm{cm}^2$, respectively. The performance of coefficient for air heating was about 3.3~4.0.