• Korean Chemical Engineering Research
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• v.61 no.3
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• pp.419-425
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• 2023

This paper presents the research results of analyzing the high-temperature corrosion characteristics of three currently commercialized heat exchanger tube materials under actual operating conditions of a biomass power plant. In order to precisely analyze the high-temperature corrosion characteristics of these materials, a high-temperature corrosion evaluation device was installed in the power plant equipment, which allows for adjusting the surface temperature of the heat exchanger tubes. Experiments were conducted for approximately 300 hours under various temperature and operating conditions. In this study, the commercialized heat exchanger tube materials used were SA213T12, SA213T22, and SA213T91 alloys. In order to objectively analyze the high-temperature corrosion characteristics of each material, an international standard-based process to remove corrosion products was applied to obtain the weight change of the specimens, and the average thickness loss and corrosion rate were derived. Thus, the high-temperature corrosion results for each condition were quantitatively compared and analyzed. In addition, in order to increase the reliability of the high-temperature corrosion evaluation method introduced in this study, the surface and cross-sectional corrosion of the specimens were confirmed by using scanning electron microscopy and energy-dispersive X-ray analysis. Based on these analysis results, it was found that the corrosion resistance of the commercial heat exchanger materials increases as the content of chrome and nickel in the composition increases. Additionally, it was found that the corrosion phenomenon is rapidly accelerated as the surface temperature increases. Finally, the replacement period (lifetime) of the heat exchanger tubes under each condition could be inferred through this study.

• Journal of the Korean Society of Combustion
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• v.18 no.2
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• pp.23-31
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• 2013

Compact steam boiler is a useful heat exchanger in a space-intensive system. There are some constraints in terms of sizing and designing the space confined in the system which is usually used in vessels. In this study, design considerations for heavy duty heat exchangers of compact steam boilers are presented and evaluated. Especially, evaporator tubes of marine boiler which are exposed to a high temperature environment are considered. Also, extended surface designs with a high temperature are examined. In order to determine the criteria with considerations of both heat transfer rate and pressure drop in the heat exchanger, they are evaluated with major variables, such as the tube diameter, the number of tubes, and the tube length. Finally, the design parameters are estimated as the bare tubes are installed instead of the finned tubes.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1226-1231
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• 2009

This paper presents operating characteristics of internal heat exchanger(IHX) for $CO_2$ geothermal heat pump in the heating mode. Mass flow rate of $CO_2$, inlet temperatures of $CO_2$ at high and low pressure side were selected as main effect factors by using fractional factorial DOE(Design of Experiments). And RSM(Response Surface Method) was used in optimization phase. The results show that heat transfer rate of IHX increases when either inlet temperature of low pressure side decreases or inlet temperature of high pressure side increases. Effectiveness of IHX increases with increasing of inlet temperature of either high pressure side or low pressure side. Finally, performance contour map was provided over the operation ranges of the main design factors.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.11
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• pp.1044-1050
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• 2004

The present study has been conducted to develop a heat pipe heat exchanger for middle-high temperature ranged from 300 to $600^{\circ}C$. Heat transfer rate, overall heat transfer coefficient and temperature effectiveness were investigated using a heat pipe heat exchanger with Dowtherm A as working fluid. Theoretical analysis was also conducted, and the followings were obtained: (1) Heat exchange rate increased as waste gas temperature supplied to evaporator and frontal velocity in condenser increased, (2) Overall heat transfer coefficient increased by $3{\sim}7\%$ as frontal velocity in evaporator and condenser increased, (3) Temperature effectiveness was about $30\%$ in evaporator and was about $40\%$ in condenser, (4) Heat recovery rate was about $38\%$, (5) Pressure drop did not exceed $8\;mmH_{2}O$ under the running condition of $1{\sim}3Nm/s$, (6) Simulation results were corresponded with experimental results.

• Journal of Convergence for Information Technology
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• v.10 no.2
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• pp.82-88
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• 2020

The purpose of this study is to obtain basic data on the optimization of firing process conditions for enamel coating in chemical heat exchanger. The method of increasing the firing temperature in order to apply enamel coating to shell & tube type heat exchanger was examined. The temperature distribution of the heat exchanger in the firing kiln was numerically calculated using a commercial CFD program. The structural safety of the heat exchanger was confirmed by thermal stress analysis using the FSI method. Numerical analysis and experimental results show that there is a problem of safety due to temperature difference when the heat exchanger at room temperature is directly put into a firing kiln at 860℃. Therefore, a preheating process is need to reduce the temperature difference. As in Case2 with fewer firing steps, the first stage preheating temperature of 445℃and the second stage firing temperature of 860 ℃are considered to be most suitable.

• Journal of the Korean Society of Combustion
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• v.14 no.3
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• pp.24-28
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• 2009

To improve its efficiency, most of the industrial furnace had been used recuperator. However, commonly used metal recuperator is not suitable under condition of temperature higher than $1000^{\circ}C$. The other hand, ceramic recuperator is able to use in high temperature condition. In the present study, the design program based on the basic heat exchanger design theory, and CFD modelling are applied to ceramic recuperator to verify the design results. Using design program to find the optimum design factor on the variation of recuperator condition. The result of this study are as follows : Thinner fin-plate thickness reduces pressure drop and increases heat-transfer rate, However, thin plate or plate with thin thickness(< 5 mm) is difficult to manufacture, due to limited mechanically strength.

• 한국연소학회:학술대회논문집
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• 2002.11a
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• pp.65-69
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• 2002

Catalytic combustion known as one of the traditional oxidation methods of VOC gas is restricted to its applicable fields because of its reaction characteristics. But recently innovative improvement of catalytic endurance makes its applicable range broader from MEMs to industrial power generation. Therefore, control technologies based on the catalytic combustion characteristics are researched and developed dynamically. Especially, the stable control of catalytic combustion is an essential factor in a view of maximizing its efficiency. In this research, the fuel equivalence ratio and the preheating temperature of mixture gas is controlled by catalytic combustion system enhanced in heat transfer with high temperature heat exchanger. As a result, the combustion characteristics of system was investigated, and both passive and active control type were compared and analyzed.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.3
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• pp.10-17
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• 2007

Design of experiments (DOE) technique has been used to design an exhaust heat exchanger to reduce the exhaust gas temperature under high load conditions in a spark-ignition engine. The DOE evaluates the influence and the interaction of a selected eight design parameters of the heat exchanger affecting the cooling performance of the exhaust gas through a limited number of experiments. The heat exchanger was installed between the exhaust manifold and the inlet of the close-coupled catalytic converter (CCC) to reduce thermal aging. To maximize the heat transfer between exhaust gas and coolant, fins were implemented at the inner surface of the heat exchanger. The design parameters consist of the fin geometry (length, thickness, arrangement, and number of fin), coolant direction, heat exchanger wall thickness, and the length of the heat exchanger. The acceptable range of each design parameter is discussed by analyzing the DOE results.

• Journal of Institute of Convergence Technology
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• v.7 no.1
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• pp.19-22
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• 2017

SI process is one of the most advanced thermochemical water splitting cycles enabling mass production of hydrogen without emitting carbon dioxide when coupled to nuclear heat energy. The highest temperature (close to $1000^{\circ}C$) required in SI process is well matched with the outlet temperature of a coolant circulating a high-temperature gas-cooled reactor at around $950^{\circ}C$. In Section 3, some heat exchangers are included to recover heats from process flows at high temperature. In this work, we designed a heat exchanger based on the $1Nm^3/hr$ $H_2$ production capacity using commercial tools for chemical process design.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.3
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• pp.595-604
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• 2001

As an improvement in the standard of living and economic growth, the demand for air conditioning equipment is increasing rapidly. Nowadays, air conditioning equipments are being used for industry, large building, house and car. There equipments were concentrated on improving heat efficiency of economic aspects while thy design heat exchanger for cooling and heating. These air conditioning equipments using heat exchanger cause a discomfort to user due to generating mist at the beginning of operating. Therefore, the user demand air of high class and quality. In this experimental study, to acquire elementary data for development of heat exchanger which be able to supply air of high quality, that is to say, possess a restraint effect of mist generation. We estimate an effect on cooling plate quality, supply air velocity, supply air temperature, cooled plate temperature and supply air relative humidity which have an influence on outlet air condition of heat exchanger.