• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.4
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• pp.331-341
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• 2013

In a solar domestic hot water (SDHW) system, solar energy is collected using collector panels, transferred to a circulating heat transfer fluid (brine), and eventually stored in a thermal storage tank (TST) as hot water. In this study, a computational fluid dynamics (CFD) model was developed to predict the solar thermal energy storage in a hybrid-type TST equipped with a helical jacket heater (mantle heat exchanger) and an immersed spiral coil heater. The helical jacket heater, which is the brine flow path attached to the side wall of a TST, has advantages including simple system design, low brine flow rate, and enhanced thermal stratification. In addition, the spiral coil heater further enhances the thermal performance and thermal stratification of the TST. The developed model was validated by the good agreement between the CFD results and the experimental results performed with the hybrid-type TST in SDHW settings.

• Journal of the Korean Institute of Gas
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• v.21 no.6
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• pp.52-60
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• 2017

In diffusion process exhaust line during semiconductor manufacturing process, In order to improve the transportation efficiency in the piping by removing "The reaction by-product, $ZrO_2$ and The unreacted material, TEMAZ, TMA, $O_3$, etc" and "Powder being deposited", the piping temperature was raised to $80^{\circ}C$ or more by using the heater jacket, and the bellows at the rear end of the vacuum pump ruptured. So conducted a case study and try to prevent the similar accidents from occurring through case studies. The causes of the accident were analyzed as follows: the inflow of outside air due to the generation of a gap on the suction side of the vacuum pump and heating the pipe with the heater jacket resulted in the overpressure in the pipe due to the volumetric expansion of the gas generated by decomposition of the unreacted TEMAZ, It can be assumed that the most vulnerable bellows of the piping has been ruptured. In order to prevent such accidents, This study is aimed to identify the cause of pipeline rupture accident and to establish safety measures for the prevention of similar accidents by evaluating physical hazards of TEMAZ, which is assumed to be the cause of pipe rupture accident.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.4
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• pp.334-341
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• 2023

The purity of hydrogen finally purified in the hydrogen purification process system is greatly influenced by the uniformity of the purification temperature of the dry tower. A in-house code that can be easily used by field designers has been developed to predict the capacity of the appropriate heat source and the time to reach the temperature of the dry tower. A code was developed to predict unsteady heat transfer using Visual Basic for Applications. To verify the developed code, a grid independence test was performed, and finally, calculations were performed for two cases. In the first case, the time for the temperature of the heater jacket to reach 360℃ was about 1,400 seconds when the supply heat source was 1,000 W. And in the second case, the time for the temperature of the heater jacket to reach 360℃ was about 710 seconds when the supply heat source was 2,000 W. It was confirmed that the developed code well describes the actual test data of the regeneration process of adsorption and desorption, and it is judged that the code developed in the design process of various capacity systems will be effectively applied to the heat capacity calculation in the future.

• Design & Manufacturing
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• v.10 no.2
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• pp.18-23
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• 2016

Injection molded thermoplastic parts may need to be coated to facilitate paint adhesion, or to satisfy other surface property requirements, such as appearance, durability, and weather resistance. In this paper, a two-component polyurethane metering system was developed for the simultaneous injection and surface coating of a plastic substrate. The system was composed of storage tanks, feed pumps, axial piston pumps, mixing head. The tank was designed to be double-jacket structured and fabricated for polyol and isocyanate, respectively. A temperature chamber was used to maintain the material temperature to be $80^{\circ}C$ during flowing from storage tank to mixing head. Inside the chamber, feed pump, low pressure filter, high pressure pump, high pressure filter, pressure sensor, flow meter were installed. A mixing head of L-type was used for homogeneous mixing of polyol and isocyanate. Inside the mixing head, a cartridge heater and a temperature sensor were installed to control the temperature of the materials. The flow rate of axial-piston pump was controlled by using closed-loop feedback control algorithm. The input flow-rates were compared with the measured values. The output error was 6.7% for open-loop control, whereas the error was below 2.2% for closed-loop control. In addition, the pressure generated through mixing-head nozzle increased with increasing flow rate. It was found that the pressure drop between metering pump and mixing-head nozzle was almost 10 bar.

• Journal of the Korean Vacuum Society
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• v.18 no.4
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• pp.318-330
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• 2009

A high heat flux test facility using a graphite heating panel was constructed and is presently in operation at Korea Atomic Energy Research Institute, which is called KoHLT-1. Its major purpose is to carry out a thermal cycle test to verify the integrity of a HIP (hot isostatic pressing) bonded Be mockups which were fabricated for developing HIP joining technology to bond different metals, i.e., Be-to-CuCrZr and CuCrZr-to-SS316L, for the ITER (International Thermonuclear Experimental Reactor) first wall. The KoHLT-1 consists of a graphite heating panel, a box-type test chamber with water-cooling jackets, an electrical DC power supply, a water-cooling system, an evacuation system, an He gas system, and some diagnostics, which are equipped in an authorized laboratory with a special ventilation system for the Be treatment. The graphite heater is placed between two mockups, and the gap distance between the heater and the mockup is adjusted to $2{\sim}3\;mm$. We designed and fabricated several graphite heating panels to have various heating areas depending on the tested mockups, and to have the electrical resistances of $0.2{\sim}0.5$ ohms during high temperature operation. The heater is connected to an electrical DC power supply of 100 V/400 A. The heat flux is easily controlled by the pre-programmed control system which consists of a personal computer and a multi function module. The heat fluxes on the two mockups are deduced from the flow rate and the coolant inlet/out temperatures by a calorimetric method. We have carried out the thermal cycle tests of various Be mockups, and the reliability of the KoHLT-1 for long time operation at a high heat flux was verified, and its broad applicability is promising.