• Journal of Power System Engineering
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• v.10 no.1
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• pp.71-76
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• 2006

This paper aims to study several type heaters which are mica heater, film heater, quartz heater and rod heater and to get an temteraturel and electrical characteristics. These four type heaters have a merit in many fields than present electric heater with nichrome wire. Carbon and mica plate heater have higher heat efficiency and less electromagnetic waves. Also it has been reported that far infrared ray emission from this heater is good for our health. Additionally heating element is thin and lighter plate. For these reasons, they will be widely used to various application such as room-heating or manufacturing goods. Experimental result confirmed that when 220V current authorized, the temperature, electric current, electric power and the resistance rise to stationary state in early stage. Moreover, the temperatures and electric characteristics show a good stability.

• Nuclear Engineering and Technology
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• v.52 no.1
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• pp.27-36
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• 2020

Natural convection and thermal stratification phenomena are found in large water pools that are being used as heat sinks for decay heat removal from the reactor core using passive heat removal systems. In this study, the two-phase (water and air) natural convection and thermal stratification phenomena with conjugate heat transfer in the rectangular enclosure were investigated numerically using ANSYS Fluent 17.2 code. The transient numerical simulations of these phenomena in the full-scale computational domain of the experimental facility were performed. Generation of water vapour bubbles around the heater rod and evaporation phenomena were included in this numerical investigation. The results of numerical simulations are in good agreement with experimental measurements. This shows that the natural convection is formed in region above the heater rod and the water is thermally stratified in the region below the heater rod. The heat from higher region and from the heater rod is transferred to the lower region via conduction. The thermal stratification disappears and the water becomes well mixed, only after the water temperature reaches the saturation temperature and boiling starts. The developed modelling approach and obtained results provide guidelines for numerical investigations of thermal-hydraulic processes in the water pools for passive residual heat removal systems or spent nuclear fuel pools considering the concreate walls of the pool and main room above the pool.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.1
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• pp.81-87
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• 2023

Heaters using the resistance heating principle are used in various industrial fields that require heat and are also essentially used in bidet among small home appliances. A planar heater and a coil-inserted heater mounted on a conventional commercially used bidet have disadvantages and limitations of complicated manufacturing process and local heating. In this study, silver-palladium (Ag-Pd) powder material was used for a screen-printing process that is more advantageous in achieving simplification than the existing process, and a rod-type heater for bidet was manufactured. The on-off cycle test under actual conditions was conducted to confirm the durability and the capability of the fabricated heater, and the fabricated heater operated more than 2,600 on-off cycles, which means it could be applied for a commercial product. In addition, through the on-off cycles under harsh conditions, the cause of failure was identified after the test that the durability limit temperature of the heater was 850℃. Through Ag-Pd rod heater in this study, it is expected to contribute to the efficient development of electrode materials for heaters and the improvement of the durability of heaters in the future.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.11 no.3
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• pp.13-19
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• 2015

This study was aimed at the heating tank with a screw-rotation device for improving the thermal efficiency of electric boiler. In the proposed system, analysis items were the heater rod surface temperature variation, reaching time for set temperature and thermal efficiency. The following conclusions are obtained from this experimental study. (1) When screw speed increases, the time reaching for set temperature tended to be shorter. (2) When the rotation speed becomes 300 rpm, the surface temperature difference between the right and left heater rod decreases by 49%, from $19.7^{\circ}C$ to $9.7^{\circ}C$ in average. (3) When the rotation speed is over 250 rpm, proposed heating tank structure appeared to be effective in terms of thermal efficiency. Thermal efficiency with the rotation speed 300 rpm is improved by 3.8% compared to the case of rotation speed 0 rpm.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.191-196
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• 2007

This paper presents the measuring technique for local heat transfer coefficients using a copper sensor in a rod bundle with mixing vanes. A copper sensor consists of a cartridge heater and four pieces of thermocouple. The Heater is located at the center of the copper sensor and thermocouples measure the surface temperature of the copper sensor. Unheated copper sensor and heated copper sensor are able to measure the local heat transfer coefficient at the position where the heated copper sensor is installed. However the entire region of a rod bundle is actually not heated, the decay of local heat transfer coefficients measured represents overestimated value rather than an actual value. The calibration curve for local heat transfer coefficients is presented using the correction factor calculated by CFD.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.195-200
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• 2001

An experimental study on critical heat flux (CHF) has been performed for water flow in a uniformly heated vertical 3 by 3 rod bundle under low flow and a wide range of pressure conditions. The objective of this study is to investigate the parametric trends of CHF with 3 by 3 rod bundle test section where three unheated rods exist. The general trends of the CHF are coincident with previous understandings. At low flow and system pressure above 3 MPa, some critical qualities are larger than 1.0 due to counter-current flow in test sections. Since there is a supply of water to the heated section from unheated section, the maximum CHFs at system pressure between 2 and 4 MPa are not shown.

• Journal of the Semiconductor & Display Technology
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• v.19 no.1
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• pp.67-72
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• 2020

This study analyzes the method of adhesion and improvement between heat.er and RF filter in PE-CVD equipment through TRIZ method and proposes a solution. TRIZ Solution such as function analysis, 9-window matrix, ASIT, and Root cause analysis were used. The contact temperature between the heater and the RF filter was 20% and the surface temperature was lowered to 5.7℃, suggesting an improvement method for the thermal expansion of the PE-CVD equipment hot zone.

• Journal of the Korean Society of Industry Convergence
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• v.21 no.5
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• pp.257-263
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• 2018

It is a small injection molding machine for table top considering the material heating mechanism and the design and structure stability by securing the mechanism that compresses the inside of the material heating tube by using the electric actuator and by providing space between the body and the material heating tube to reduce heat loss Develop body. An electric actuator suitable for applying pressure to the inside of a material heating tube is a mechanical system composed of a rigid structure. Since a large force is repeatedly applied to the electric actuator and the push rod, the interaction between the moving parts and the dynamic Maximum stress through analysis and prediction of fatigue life of critical parts The pushrod reflects the structural analysis results of the electric actuator and the push rod, and pushes the inside of the material heating tube by the push rod to inject the molten material from the nozzle into the mold. The pushrod operates by the operation of the electric actuator. The material heated by the coil heater is ejected through the nozzle by the pressure of the material heating tube, and the material heating tube and the nozzle are also lowered at the same time as the push rod is lowered, so that the material is closely adhered to the mold. We want to study the completion of the injection.

• Journal of the Korean Society of Visualization
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• v.18 no.3
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• pp.23-34
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• 2020

Two-phase flow and heat transfer characteristics during the reflood phase of a single heated rod in the KHU reflood experimental facility were examined. Two-phase flow behavior during the reflooding experiment was carefully visualized along with transient temperature measurement at a point inside the heated rod. By numerically solving one-dimensional inverse heat conduction equation using the measured temperature data, time-resolved wall heat flux and temperature histories at the interface of the heated rod and coolant were obtained. Once water coolant was injected into the test section from the bottom to reflood the heated rod of >700℃, vast vapor bubbles and droplets were generated near the reflood front and dispersed flow film boiling consisted of continuous vapor flow and tiny liquid droplets appeared in the upper part. Following the dispersed flow film boiling, inverted annular/slug/churn flow film boiling regimes were sequentially observed and the wall temperature gradually decreased. When so-called minimum film boiling temperature reached, the stable vapor film between the heated rod and coolant was suddenly collapsed, resulting in the quenching transition from film boiling into nucleate boiling. The moving speed of the quench front measured in the present study showed a good agreement with prediction by a correlation in literature. The obtained results revealed that typical two-phase flow and heat transfer behaviors during the reflood phase of overheated fuel rods in light water nuclear reactors are well reproduced in the KHU facility. Thus, the verified reflood experimental facility can be used to explore the effects of other affecting parameters, such as CRUD, on the reflood heat transfer behaviors in practical nuclear reactors.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.11
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• pp.151-159
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• 2016

This paper proposes a ceramic heating element-based tankless instant electric water heater for hand/face washing that does not require a lot of hot water. The heating module, which heats the input water and outputs hot water, operates the ceramic heating element detecting input water using a flow sensor. Inside of the heating module is designed to form one flow path in order to get almost $15^{\circ}C$ increased heated water compared to the input water temperature within 2 second after 1.5 liter per minute water supply. The design validity is verified using a heat flow analysis of the water flow and temperature variations inside of the heating module also. Based on the design data, the heating module is constructed including a single rod-type ceramic heating element. After that, a prototype system having temperature setting function by three steps were constructed. The prototype system is connected to a 1.5 liter per minute water supply line, and the water output temperature and time measurement experiments confirmed that the proposed system output the heated water increased by $18.3^{\circ}C$ in case of third step setting within 2 second after water supply. And standby power is under 1 W and peak power does not exceed the permissible range for the general house usage. Several performance results verify that the proposed tankless instant electric water heater is applicable for the washstand of the house, highway rest area and factory so on as winter-time hand/face washing.