• KIEAE Journal
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• v.17 no.4
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• pp.41-48
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• 2017

Purpose : Currently, 25% of the domestic energy consumption structure is used as building energy, and more than 18% of this energy is consumed in the residential. Accordingly, various efforts and policies that can save energy of the building is being performed. The various researchers are conducting research to diagnose the thermal performance of existing buildings. This study is to apply in the field of precision thermal insulation performance diagnostic method for thermal performance analysis of existing detached house in Seoul, Gangreung, Gyeongju, Pohang. And this paper is analyzed quantitatively measure the existing detached house energy performance. Method: Research methodology analyzed the thermal performance over the Heat Flow Meter method by applying the measurement process and method by applying the criteria of ISO 9869-1 & ASTR method. In this study, the surface heat transfer coefficient was calibrated by applying indoor surface heat transfer resistance with reference to ISO 6946 standard. The measurement error rate between the HFM diagnosis method and the ASTR diagnosis method was reduced and the measurement reliability was obtained through measurement method error verification. Result : As a result of the study, the thermal performance vulnerable parts of the building were quantitatively analyzed, and presented for methods which can be improved capable of efficient energy use buildings.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.6
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• pp.104-111
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• 2006

A ventilated disc brake having spirally fluted surface has been proposed to improve the thermal judder by way of heat transfer enhancement. The local heat transfer coefficients were measured in the flow passage of disc brake. These measured local heat transfer data were utilized to do the finite element numerical analysis which predicts the maximum temperatures on the disc brake. The results show that the maximum temperatures on the disc surface with spirally fluted surface are approximately 26.6% lower than those without them.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.5
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• pp.1300-1310
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• 1990

Naphthalene sublimation technique is employed to investigate the mass transfer processes from a square cylinder at various Reynolds numbers and various angles of attack. Distribution of the local mass transfer coefficients on each face of the cylinder changes dramatically with the angle of attack. Such variation of local mass transfer rates closely connected with the complex flow phenomena such as stagnation, acceleration, separation, reattachment and vortex shedding. The average Sherwood number has a minimum value at 12.deg.-13.deg., and a maximum value at a=20.deg.-25.deg. A comparison of present mass transfer measurement with other heat transfer measurements, using the heat/mass transfer analogy, shows good agreement in average transfer rates, same trend but notable differences in local values. Therefore, naphthalene sublimation technique can be adopted to explore heat transfer processes in the complex flow situations, which is considered to be hardly possible with the conventional heat transfer measurements.

• KEPCO Journal on Electric Power and Energy
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• v.6 no.2
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• pp.151-155
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• 2020

In this paper, a new experimental method to determine the thermal resistance of building wall was proposed by improving the heat flow method (HFM) based on the air-surface temperature ratio theory. This technique measures the thermal resistance of the wall excluding the inner and outer surface heat transfer resistance. Unlike conventional HFM, this value can be compared directly with the theoretical reference value. Its performance was verified using three mock-up structures with a theoretical thermal transmittance of 0.5, 3.3, and 0.18 W/㎡·K respectively. After measuring the variations in the temperature and heat transfer rate of the mock-ups for 383 hours, the thermal transmittances were determined to be 0.47, 3.10, and 0.18 W/㎡·K, which corresponded to errors of 5.2, 6.2 and 0.5%, respectively, compared to the theoretical values. It was concluded that this technique can directly compare the thermal resistance of the wall between the existent stage and initial stage after construction.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10c
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• pp.19-24
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• 1998

In this study, blended cement with low blaine(2000, 3000$\textrm{cm}^2$/g) blast-furnace slag power by 10-70wt.% was investigated through the measurement hydration heat, physical properties. The experiment results indicated compressive strength was decreased as low blaine slag blended, but hydration heat was reduced significantly and flow of the cement paste was increased.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.2
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• pp.103-116
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• 1994

In this study the behavior of engine cooling loss and overall heat transfer coefficient were studied experimentally using naturally aspirated engine and turbo charged engine. Using turbo charging, heat dissipation was increased because of the density of the mixture was increased with increment of inlet air flow rate. Therefore, cooling loss of turbo charged engine is larger than naturally aspirated engine. As taking the measurement of surface temperature of combustion chamber, gas heat transfer coefficient was calculated and found that it has greatly affected to overall heat transfer coefficient. The empirical formula of overall heat transfer coefficient established in order to predict of engine cooling loss and express only as a function of mean piston velocity.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.359-362
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• 2006

Infra-red thermography was conducted to understand a heat transfer characteristic on a surface protruded to a supersonic flowfield. Surface temperature distribution was obtained under the constant heat flux condition with a infra-red camera and the convective heat transfer coefficient distribution was calculated. Finally, two dimensional distribution of heat transfer coefficient on a surface around a cylinder body was derived.

• Proceedings of the Korean Nuclear Society Conference
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• 1999.05a
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• pp.104-104
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• 1999

The local heat transfer coefficient is experimentally investigated for the reflux condensation in a countercurrent flow between the steam-air mixture and the condensate. A single vertical tube has a geometry which is a length of 2.4m, inner diameter of 16.56mm and outer diameter of 19.05mm and is made of stainless steel. Air is used as a noncondensible gas. The secondary side is installed in the form of coolant block around vertical tube and the heat by primary condensation is transferred to the coolant water. The local temperatures are measured at 15 locations in the vertical direction and each location has 3 measurement points in the radial direction, which are installed at the tube center, at the outer wall and at the coolant side. In three different pressures, the 27 sets of data are obtained in the range of inlet steam flow rate 1.348 -3.282kg/hr, of inlet air mass fraction 11.8 -55.0%. The local heat transfer coefficient increases as the increase of inlet steam flow rate and decreases as the decrease of inlet air mass fraction. As an increase of the system pressure, the active condensing region is contracted and the heat transfer capability in this region is magnified. The empirical correlation is developed represented with the 165 sets of local heat transfer data. As a result, the Jacob number and film Reynolds number are dominant parameters to govern the local heat transfer coefficient. The rms error is 17. 7% between the results by the experiment and by the correlation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.4
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• pp.243-250
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• 2011

In order to investigate the effects of PAG oil concentration on heat transfer performance and pressure drop during gas cooling process of $CO_2$, the experiments on fin-tube heat exchanger of $CO_2$ heat pump were performed. The experimental apparatus consists of a gas cooler, a heater, a chiller, a mass flow meter, a pump and measurement system. Experiments were conducted in various experimental conditions, which were inlet temperature($110^{\circ}C$), mass flow rates (50, 55, 60, 65, 70 g/s) and PAG oil concentration(0 to 2.6 wt%). Heat transfer rate decreased with the increase of the oil concentration and the decrease of inlet pressure. And pressure drop increased with the increase of the oil concentration and mass flow rate of refrigerant. The COP reduction by deterioration of gas cooler performance with oil concentration was analyzed. When inlet pressure of gas cooler is 100 bar, the COP reduction was estimated by 6% under 1 wt% of oil concentration.

• Journal of Bio-Environment Control
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• v.9 no.4
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• pp.212-222
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• 2000

This study was performed to investigate the performance of heat recovery device attached to exhaust gas flue connected to combustion chamber of greenhouse heating system. The experimental heat recovery system is mainly consisted of LPG combustion chamber and two heat recovery units; unit-A is attached directly to the exhaust gas flue, and unit-B is connected with unit-A. Heat recovery performance was evaluated by estimating total energy amounts by using enthalpy difference between two measurement points together with mass flow rate of gas and/or air passing through each heat recovery unit depending on 5 different flow rates controlled by voltage meter. The results of this experimental study, such as heat exchange behavior of supply air tubes and exhaust air passages crossing the tubes, pressure drop between inlet and outlet, heat recovery performance of exchange unit, etc., will be used as fundamental data for designing optimum heat recovery device to be used for fuel saving purpose by reducing heat loss amounts mostly wasted outside of greenhouse through flue.