The heat transfer characteristics of double-pipe spiral heat exchanger were investigated by various curvature sizes, experimentally. The three different sizes of heat exchanger were made and tested with water as a working fluid to analyze the heat transfer characteristics. The heat transfer rates, overall heat transfer coefficient and pressure drop were analyzed with various heat exchanger sizes (i.e., curvature ratios). As result, the heat transfer rate increased with increasing the size of the heat exchanger as the flow rate increased due to increasing the area size of heat transfer. However, the overall heat transfer coefficient and pressure drop increased with decreasing the heat exchanger size (i.e., increased curvature ratio) due to the enhanced centrifugal force and inertia.

A spiral flow path was applied to solve the problem of the existing straight flow path in the leveling shaft, a key component of the self-levelizer that can maintain the height according to the change in payload in EV, SUV. In this study, flow analysis was performed to check the velocity, pressure drop, and flow direction of oil according to the main operating conditions of the leveling shaft with a spiral flow path. As a result of the study, a leveling shaft with a spiral flow path is likely to improve fluid properties around the orifice and inlet valve under compression conditions, and it is judged to have a development application effect.

We developed a wet scrubber by applying cyclone flow to the gas flow and using a spiral filter structure. While the size of a new scrubber was about half that of a conventional scrubber, the device showed relatively high efficiency in pollutants removal such as particulate matter and compounds inducing odor. The new scrubber installed in a plating industry showed a higher removal efficiency of about 5% for dust, about 23% for hydrogen chloride, and about 23% for sulfur dioxide compared to the conventional scrubber. Plurality of tubes in the spiral filer housing are arranged to be vertically shifted from each other. Because the upward residual gas does not directly rise vertically, the residence time of gas between the filter plates is extended. Thus, the purification efficiency of the pollutants was enhanced in the new scrubber. In addition, the new scrubber developed in this study is more cost effective because the cost saving in manufacturing it compared with a conventional scrubber increases with increasing the size of equipment. It is expected that a scrubber with better dust collecting efficiency can be obtained by carrying out a study in connection with facilities capable of controlling acidity of washing water.

In this study, the CFD analysis was performed by changing the geometry of coil-tube diameter ratio, coil winding number, coil pitch, and cross section of the tube to investigate the heat flow characteristics of forced convection in a helical coil-tube heat exchanger using RSM (Reynolds Stress Model). As a result, the secondary flow was developed in the tube caused by the influence of centrifugal force. It improved the heat transfer on the outer side of the tube, but on the inner side was not performed well. And the temperature rose locally in the tube region. Also the pressure drop in the tube was proportional to the diameter ratio of the coil-tube and the inlet velocity, and it was found that pressure drop and friction factor were inversely proportional. When the coil winding number and coil pitch were increased, it affected heat transfer in the low speed range of 0.1 ~ 0.2 m/s, but did not affect the flow condition after this range.

In this study, load transfer tests based on KCI-PS101 were conducted to verify the performance of spiral anchorage zone reinforcement for banded post-tensioning (PT) monostrands. With results, the compressive strength of spiral reinforcement was increased by about 20% than that of specimens with two horizontal steel bars and 8% than that of U-shaped bars. Advanced spiral reinforcement for corner increases compressive strength and can resist the spalling forces or fall-out effect at the corner by shear. The ratio of maximum load to amount of steel of the spiral reinforcement is about twice than that of U-shaped reinforcement. With increase of compressive strength capacity and improvement of constructability, the spiral reinforcement is considered to have advantages of promoting the performance of PT anchorage zone compared to conventional methods.

본 논문에서는 변위응답 및 가속도 응답의 저감 효과에 있어서, 유리한 형상인 180° 나선형(Helical 180°) 초고층건물을 대상으로 풍진동실험을 수행하여 나선형 초고층건물의 공력불안정 진동 특성 및 공력감쇠 특성을 조사하였고, 정방형 초고층 건물의 결과와 비교분석 하였다. 본 연구에서의 공력감쇠율은 RD법(random decrement technique)을 이용하여 평가하였다. RD법에 의해 평가된 공력감쇠율은 기존문헌 및 준정상가정이론 결과와 비교·검증하였다. 실험결과, 공력진동 실험결과 180° 나선형모형의 풍직각방향에 대한 공력불안정 진동은 발생하지 않는 것이 확인되었다. 정방형과 180° 나선형 형상에 대한 공력감쇠율을 살펴보면, X방향에 대한 공력감쇠율은 무차원 풍속이 증가와 비례하여 점진적으로 증가하는 경향이 나타났다. 반면, Y방향에 대한 공력감쇠율은 정방형모형과 매우 다른 양상이 나타나는 것을 알 수 있었다.

The heat transfer characteristics of a spiral type EGR cooler for a diesel engine are numerically analyzed to investigate the performance of EGR cooler. The commercial code FLUENT is utilized to simulate a single spiral tube with constant wall temperature conditions. The numerical analysis is performed with the variation of exhaust gas flow rate. The results show that as mass flow rate increases, temperature difference between inlet and outlet and efficiency become lower, while heat flux gets higher. The empirical correlation is derived in forms of Nusslet number and Reynolds number based on the numerical results.

In this study, the performance characteristics of EGR Cooler applying to the current commercial vehicle was analyzed by the numerical analysis. Through the experiment the performance evaluation of EGR Cooler must need a lot of time and expenses. On the other hand, the numerical analysis has been used in many research areas as a way to reduce the cost and time. The analysis model of this study has a spiral shape tube. The exhaust gas passes through the inside of the tube. The performance of Cooler was analyzed according to the variation of gas mass flow rate. The results of analysis and experimental was confirmed that was indicating the same trend.

In order to investigate the confinement behavior of reinforced concrete columns using high strength materials, we performed loading tests on the columns with different combinations of reinforcement strength. Base on the test results together with previous studies, the confinement capacity of high strength reinforced concrete column was evaluated and the adequacy of the confinement design equation in the KCI code was discussed. As a result, it is found that the energy dissipation capacity increases as the yield strength increases.

This study aimed to remove organic matter and heavy metals that could affect the recycling of soils contaminated by heavy metals, by means of electrolysis, carried out simultaneously with the leaching of the soil. To ensure better experimental equipment, a soil electrolysis apparatus, equipped with spiral paddles, was used to agitate the heavy-metal-contaminated soil effectively. The heavy-metal-contaminated soil was electrolyzed by varying the voltage to 5 V(Condition 1), 15 V(Condition 2), and 20 V(Condition 3), under the optimal operating conditions of the electrolysis apparatus, as determined through previous studies. The results showed that the pH of the electrolyte solution and the heavy-metal-contaminated soil, after electrolysis, tended to decrease with an increase in voltage. The highest removal efficiencies of TOC and CODCr were 18.8% and 29.1%, 38.8% and 4.2%, and 33.3% and 50.0%, under conditions 1, 2 and 3, respectively. Heavy metals such as Cd and As were not detected in this experiment. The removal efficiencies of Cu, Pb and Cr were 4.7%, 8.3% and 2.1%, respectively, under Condition 1, while they were 42.9%, 15.2% and 22.1%, respectively, under Condition 2, and 4.7%, 23.0%, and 24.9%, respectively, under Condition 3. These results suggest that varying the voltage with the soil electrolysis apparatus for removing contaminants for the recycling of heavy-metal-contaminated soil allows the selective removal of contaminants. Therefore, the results of this study can be valuable as basic data for future studies on soil remediation.