• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.397-402
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• 2012

The objective of this study is the estimation of the two unknown thermal conductivity and thermal diffusivity by an inverse heat conduction analysis using the Levenberg-Marguardt method. One dimensional formulation of heat conduction problem in the model was applied. Two point transient temperature of test pieces and heat flux of inflow were measured under the high enthalpy flow environment. Estimated thermal conductivity and thermal diffusivity by an inverse analysis were compared with the known values of graphite test piece. It showed the effectiveness of proposed experimental inverse analysis.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.3
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• pp.439-447
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• 2002

The microchannel flow in miniature TCDs (thermal conductivity detectors) is investigated numerically. The solutions based on the boundary layer approximation are not very accurate in the region of the duct inlet for low Reynolds numbers. In this study, two-dimensional Navier-Stokes equations are considered to analyze the gas flow in a miniature TCD. Effects of channel size, inlet and boundary conditions on the heat transfer rate are examined. When the gas stream is not preheated, the distances for a miniature TCD to reach the conduction-dominant region for duct flow are found to be approximately two and three times the thermal entry length for duct flow with constant properties, respectively, leer constant wall temperature and constant wall heat flux boundary conditions. If the gas temperature at the channel inlet is close to the mean gas temperature in the conduction-dominant region, the entrance region is much shorter compared to other cases considered in this study.

• Journal of the Korean Society of Industry Convergence
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• v.3 no.3
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• pp.265-273
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• 2000

Basic simulation program for Vuilleumier cycle heat pump was developed that can use precise VMHP design and analysis. VMHP system was divided 11 sections in simulation. Simulation was used adiabatic model analysis and that considered with heat transfer performance for heat exchanger, regenerator loss, conduction loss, shuttle loss, pumping loss and pressure loss by flow friction. Specially, friction loss of connection pipe between heat compression side and heat pump side, leakage of rod seal and piston seal was considered in the analysis.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.395-401
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• 2008

Since metallic foam will increase the performance of heat exchanger, it have caused many researcher's attention recently. Our research base on the model that metallic foams applied to heat exchanger. In this case, there is three kind of heat transfer mechanisms, heat conduction in fibers, heat transfer by conduction in fluid phase, and internal heat change between solid and fluid phases. In this paper we study both the hydraulic and thermal aspect performance. Pressure drop along air flow direction will be presented. As thermal aspect, we first discuss the acceptance of applying thermal equilibrium among the two phases. then to calculate the dimensionless temperature profile, the heat transfer coefficient and Nu number in 14 metallic foams(7 Aluminium foams, 7 FeCrAlY foams). All these discussion is based on the same velocity u=2 m/s.

• Journal of Power System Engineering
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• v.7 no.3
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• pp.35-39
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• 2003

In this paper, the heat transfer phenomena in the sensor tube of a mass flow controller(MFC) were studied by experiments. In the sensor tube of MFC, the difference of temperature between inlet and outlet was necessary for calculating the mass flow rate. Therefore, the relations of flow rate, generated heat by heating wire, sensor location and tube thickness were investigated to find the optimized condition. Based on this study, static and dynamic characteristics of sensor can be used for mass flow controller.

• International Journal of Safety
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• v.11 no.2
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• pp.5-9
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• 2012

The discharge properties of super high-pressure mercury lamp are due to resistance heating for energy input, and results in temperature increase. The cooling equilibrium state is reached by the heat conduction, convection and radiation. In order to predict the fluid flow and heat transfer in and around the mercury lamp accurately, its visualization is of utmost importance. Such visualization is carried out by CFD program in this study. We focus on Anode shape to calculate four cases, namely AA, AB, AC and AD separately, and compare the temperature distribution and velocity vector in each case to predict cooling capacity and fluid flow properties. It can be concluded that the shape of anode plays an important role that affects the fluid flow and heat transfer in a mercury lamp.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.10a
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• pp.269-273
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• 2003

In this paper the HTS current lead for superconducting device is studied numerical method. The current lead is cooled by surrounded He gas by natural convection. To find wall heat flux, the linearization method is adopted Numerical results using natural convection cooling are compared with conventional cooling methods such as conduction cooling and vapor cooling. The results shows that the minimum heat dissipation is much smaller than conduction cooling. Also, the minimum heat dissipation is obtained for the non-zero gradient of temperature at warm end. HTS current lead operating current sharing mode is reduce heat flow to superconducting system.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.8 no.2
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• pp.73-80
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• 1979

This study describes the conduction of heat in the discharge head of air compressor. It also gives a base for a finite elements analysis of two dimenional steady -state heat conduction in the cylinder head of air cooled type reciprocating compressor. Using a single cylinder compressor operated at a given speed, tests were made observing outside temperature, final pressure and discharge temperature of air in cylinder head. As a result, the following were obtained : (1) The rate oi heat flow from the inner surface of discharge head to outside wall reach 46. 328 kcal /h at a speed of 796rpm under the constant temperature of inlet air. (2) The compression work of air increase in accordance with temperature rise of inlet air.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.199-204
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• 2003

In the present study, the compression process in scroll compressor was simulated in consideration of flow leakage and heat transfer. Tangential and radial leakages of the refrigerant between the scrolls were considered as nozzle flow. The experiment was first conducted with a scroll compressor for automobile air conditioning system and R134a as a refrigerant. Temperature and pressure were measured at the suction and discharge ports of the compressor to determine the thermodynamic states of the refrigerant flow. Temperature distribution of the scroll with the involute angle was also measured by thermocouples that were installed inside the scroll. Measured temperature distribution was compared with the numerical results. From this result, the thermal effect of mechanical contact was found to be important in heat transfer of the compression process.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.194-198
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• 2006

In this study, numerical modeling was performed to analyze air flow including radiation heat transfer inside a small chamber. Characteristics of heat transfer between source plate and target through glass are investigated for various surface temperature of heat source plate with buoyancy effect due to gravity force. Conduction heat transfer through the glass is considered and heat source plate is assumed to be a black body. Target surface temperature is largely affected by the radiation heat transfer. It can also be seen that as the source temperature increases target surface is dominated by radiation rather than convective heat transfer by air.