• Proceedings of the KSME Conference
• /
• 2007.05b
• /
• pp.3062-3067
• /
• 2007

HVOF thermal spray guns are now being widely used to produce protective coatings, on the surfaces of engineering components. HVOF technology employs a combustion process to heat the gas flow and melt the coating materials which are particles of metals, alloys or cermets. Particle flow which is accelerated to high velocities and combustion gas stream are deposited on a substrate. In order to obtain good quality coatings, the analysis of torch design must be performed. The reason is that the design parameters of torch influence gas dynamic behaviors. In this study, numerical analysis is performed to predict the gas dynamic behaviors in a HVOF thermal spray gun with various torch shapes. The CFD model is used to deduce the effect of changes in nozzle geometry on gas dynamics. Using a commercial code, FLUENT which uses Finite Volume Method and SIMPLE algorithm, governing equations have been solved for the pressure, velocity and temperature distributions in the HVOF thermal spray torch.

• 한국태양에너지학회:학술대회논문집
• /
• 2009.04a
• /
• pp.49-54
• /
• 2009

This study focus on verification of the thermal efficiency of volumetric receiver with $5kW_{th}$ Dish-type solar thermal system. Spiral flow path shaped on receiver and working fluid(steam) flow along the this flow path. Porous material for radiation-thermal conversion used in former researches are substituted with the stainless steel wall installed along the spiral shaped flow path. Numerical analysis for the flow path and temperature distributions are carried out. Numerical results are compared with experimental data. Using the numerical model, the heat transfer characteristics of spiral type receiver for dish-type solar thermal systems are known and the thermal performance of the receiver can be estimated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.07b
• /
• pp.1113-1116
• /
• 2004

This paper presents the method for analyzing surface temperature of Electric incoming Apparatus. For the experiment, the surface temperature of electric power apparatus was measured and analyzed by using a infrared thermal imaging system. Surface Discharges(SD) have very complex characteristics of discharge patterns, therefore it requires the development of precise analysis methods. recently, studies on infrared thermal imaging system are carried out to analyze temperature distribution of power equipments through condition diagnosis and to diagnose the degradation of power equipments. The changes in suface temperature was measured by using the infrared thermal imaging system under hot line condition. The system was set up based on the diagnostic method of the electric incoming apparatus.

• Journal of Power System Engineering
• /
• v.3 no.3
• /
• pp.14-21
• /
• 1999

The wave nature of heat conduction has been developed in situations involving extreme thermal gradients, very short times, or temperatures near absolute zero. Under the excitation of a periodic surface heating in a finite medium, the hyperbolic and parabolic heat conduction equations and the damped wave equations in heat flux are presented for comparative analysis by using the Green's function with the integral transform technique. The Kummer transformation is also utilized to accelerate the rate of convergence of these solutions. On the other hand, the temperature distributions are obtained through integration of the energy conservation law with respect to time. For hyperbolic heat conduction, the heat flux distribution does not exist throughout all the region in a finite medium within the range of very short times(${\xi}<{\eta}_l$). It is shown that due to the thermal relaxation time, the hyperbolic heat conduction equation has thermal wave characteristics as the damped wave equation has wave nature.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 1995.03a
• /
• pp.9-16
• /
• 1995

The thermal deformation of machine tool spindle influences the performance of the manufacturing systems for precision products. In this research thermal analysis of a high speed machine tool spindle with the rolling bearing and the built-in motor is carried out using Finite Difference Method. The thermal boundary conditions describing the hear generation in the bearing and built-in motor are considered in the simulation. And various convective boundary conditions are assumed with the empirical formula in the references. From the simulation results the characteristics of each element affecting the dynamic thermal behaviour of the machine tool spindle systems have been clarified. This model can be well applied to the future development of the high speed spindle systems.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.5 no.1
• /
• pp.162-173
• /
• 1997

A 3-dimensional finite element model was developed for the analysis of the automotive diesel engine piston. The model, which consists of a full piston to accomodate the eccentric bowl in the piston crown, is used to calculate steady state operating temperature, thermal stress and thermal deformation of the piston. Roundness measurement tests, which are new approaches to the analysis of piston abrasion and deformation, were done for the comparision of two states of a piston-before and after operation. Numerical prediction shows good agreement with roundness measurement test results.

• International Journal of Air-Conditioning and Refrigeration
• /
• v.14 no.4
• /
• pp.125-130
• /
• 2006

This study has been performed to investigate the thermal performance of variable conductance heat pipe (VCHP) with screen meshed wick. The active length of condenser section in a VCHP is varied by non-condensible gas, which controls the operating temperature, and the heat capacity of VCHP is controlled by the operating temperature. In this study, numerical analysis of the VCHP based on the diffusion model of non-condensible gas is done for the thermal control performance of VCHP. Water is used as a working fluid and nitrogen as a control non-condensible gas in the copper tube. As a result, the thermal conductance of VCHP has been compared with that of constant conductance heat pipe (CCHP) corresponding to the variation of operating temperature.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.10 no.1
• /
• pp.48-59
• /
• 2018

This paper is mainly concerned with developing the formulae of predicting thermal deformation of steel plate due to multi-line heating. By investigating the results of line heating test and numerical analysis, reasonable heat flux model has been defined. Formulae of predicting the transverse shrinkage and the angular distortion as the dominant thermal deformation types in plate forming by line heating have been derived based on the results of line heating test and numerical analysis with varying plate thickness, heating speed and distance between torches. This paper illustrates how the derived formulae are used in investigating the effect of multi-line heating upon the thermal deformation and how they can be used in defining the limit distance with that there is no interacted effect between torches. This paper ends with describing the extension of the present study.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.58 no.4
• /
• pp.499-504
• /
• 2009

The analysis for furan compound has provided a complementary technique to dissolved gas analysis(DGA) for monitoring transformers when total concentration of CO and $CO_2$ dissolved in oil only has been evaluated the aging of insulating paper. But, the analysis of furanic compounds by high performance liquid chromatography(HPLC) has been important more than DGA recently. Because it has been known that furanic components in transformer oil have come only from the decomposition of insulating paper. Therefore we have manufactured accelerating aging cell which was aged during 60 hours at 100, 150, 180 and $200^{\circ}C$, respectively, for investigating the characteristics of cellulose paper by thermal using analysis for CO, $CO_2$ and furan compound.

• Journal of Institute of Convergence Technology
• /
• v.1 no.1
• /
• pp.5-8
• /
• 2011

Thermal analysis of a cooling module using Peltier elements are performed using a commercial software, CFD-ACE+. A standard k-e two-equation turbulent model is applied in order to represent the turbulent shear stress. Computed values are compared with the theoretical values for the validation. The effect of mass flow rates and transferred heat amounts on the temperature distributions inside the cooling system is analyzed. It was found that the increase in the mass flow rates causes the exit temperature rise. The increase in the absorbed heat amount diminished the overall temperature on the fin surfaces. In the present analysis, the material characteristics of the Peltier element itself are not considered. In the future, the effect of the turbulence models and material characteristics will be studied in detail.