Hwalong You

Korea Institute of Machinery and Materials

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Daejun Chang

Korea Advanced Institute of Science and Technology

Byung-Il Choi

Korea Institute of Machinery and Materials

Minchang Kim

Korea Institute of Machinery and Materials

Yong-Shik Han

Korea Institute of Machinery and Materials

Changhyun Kim

Korea Institute of Machinery and Materials

Junkeon Ahn

Institute for Advanced Engineering

Kyuhyung Do

Korea Institute of Machinery and Materials

Youngkyun Seo

Korea Research Institute of Ships and Ocean Engineering

Kyu Hyung

Korea University of Science and Technology

Cheol Huh

Korea Maritime and Ocean University

Cooperative Institutions

Korea Advanced Institute of Science and Technology

Korea Institute of Machinery and Materials

Korea University of Science and Technology

Seoul National University

Samsung (South Korea)

Korea University

Sungkyunkwan University

Korea Institute of Materials Science

Hyundai Heavy Industries (South Korea)

Lattice Semiconductor (United States)

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A Prismatic Pressure Vessel With Lattice Structure and Applications in LNG Field

The 27th International Ocean and Polar Engineering Conference (2017)

Hwalong You Junkeon Ahn Choonghee Jo Pál G. Bergan Daejun Chang

Lattice (music)

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Pressure drop and thermal resistance characteristics of plain-fin heat sink with impingement flow

International Journal of Thermal Sciences (2023)

Taehoon Kim Yong-Shik Han Hwalong You Changhyun Kim Minchang Kim

Despite extensive research on plain-fin heat sinks with impinging flow, there have been few studies that evaluate the impact of flow nonuniformity on their performance, in spite of the fact that flow nonuniformity at the inlet is a key factor affecting heat sink performance. This study developed a novel methodology to quantitatively assess the flow nonuniformity at the heat sink inlet by combining experimentally measured pressure distributions and numerical analysis. Experiments were conducted with varying flow rates and fin heights ranging from 40 L/min to 180 L/min in the range of 5 mm–25 mm, respectively. A flow nonuniformity index was used to quantify the flow nonuniformity at the heat sink inlet, and its values ranged from 0.2 to 1.3 in all experimental cases. The study demonstrated that flow uniformity can be improved by increasing both the fin height and flow rate. The nonuniformity index-based region map was introduced to estimate the heat sink's thermal resistance and pressure drop behaviors under impingement flow. The study found that the flow condition at the heat sink inlet can be considered as a uniform flow condition when the flow nonuniformity index is less than 0.2, which indicates that the fin height is 25 mm and the Reynolds number is greater than 350 in the present experiments. The heat sink's thermal performance under uniform flow condition was superior to that under nonuniform flow condition at a constant flow rate. In conclusion, the flow condition at the heat sink inlet, along with geometric configuration and flow rate, plays a critical role in the plain-fin heat sink performance with impingement flow.

Fin

Sink (geography)

Flow coefficient

10.1016/j.ijthermalsci.2023.108598

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Performance Analysis of Cold Energy Recovery from CO2 Injection in Ship-Based Carbon Capture and Storage (CCS)

Energies (2014)

Hwalong You Youngkyun Seo Cheol Huh Daejun Chang

Carbon capture and storage (CCS) technology is one of the practical solutions for mitigating the effects of global warming. When captured CO2 is injected into storage sites, the CO2 is subjected to a heating process. In a conventional CO2 injection system, CO2 cold energy is wasted during this heating process. This study proposes a new CO2 injection system that takes advantage of the cold energy using the Rankine cycle. The study compared the conventional system with the new CO2 injection system in terms of specific net power consumption, exergy efficiency, and life-cycle cost (LCC) to estimate the economic effects. The results showed that the new system reduced specific net power consumption and yielded higher exergy efficiency. The LCC of the new system was more economical. Several cases were examined corresponding to different conditions, specifically, discharge pressure and seawater temperature. This information may affect decision-making when CCS projects are implemented.

Exergy efficiency

Degree Rankine

Organic Rankine Cycle

10.3390/en7117266

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Citations (12)

Strategy for selecting an optimal propulsion system of a liquefied hydrogen tanker

International Journal of Hydrogen Energy (2017)

Junkeon Ahn Hwalong You Jiheon Ryu Daejun Chang

This study proposed a strategy for selecting an optimal propulsion system of a liquefied hydrogen tanker. Four propulsion system options were conceivable depending on whether the hydrogen BOG (boil-off gas) from the cryogenic cargo tanks was used for fuel or not. These options were evaluated in terms of their economic, technological, and environmental feasibilities. The comparison scope included not only main machinery but also the BOG handling system with electric generators. Cost-benefit analysis, life-cycle costing including carbon tax, and an energy efficiency design index were used as measures to compare the four alternative systems. The analytic hierarchy process made scientific decision-making possible. This methodology provided the priority of each attribute through the use of pairwise comparison matrices. Consequently, the propulsion system using LNG with hydrogen BOG recovery was determined to be the optimal alternative. This system was appropriate for the tanker that achieved the highest evaluation score.

Scope (computer science)

Liquid hydrogen

10.1016/j.ijhydene.2017.01.037

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Citations (49)

CO2 Injection System with CO2 Cold Energy Recovery

The Twenty-fourth International Ocean and Polar Engineering Conference (2014)

Hwalong You Youngkyun Seo Cheol Huh Daejun Chang

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Citations (1)

Evaluation of CO2 liquefaction processes for ship-based carbon capture and storage (CCS) in terms of life cycle cost (LCC) considering availability

International journal of greenhouse gas control (2015)

Youngkyun Seo Hwalong You Sanghyuk Lee Cheol Huh Daejun Chang

Unavailability

Operating expense

Operating cost

Capital cost

10.1016/j.ijggc.2015.01.006

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Citations (63)

Analysis of Cool-down Operation of Liquid Hydrogen Tank

Journal of Hydrogen and New Energy (2023)

Hwalong You Byung-Il Choi Kyuhyung Do T. Kim CHANGHYUN KIM

10.7316/jhne.2023.34.6.641

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A Simple Predictive Method for Estimating Bor Over Time in a Cryogenic Container

Journal of Fluids Engineering (2024)

Changhyun Kim Taehoon Kim Hwalong You Minchang Kim Yong-Shik Han

Abstract Recently, cryogenic fluids are widely transported via cargo ships as energy sources. The generation of boil-off gas (BOG) is inevitable in a cryogenic container due to the large temperature difference. Therefore, accurately analyzing the boil-off gas over time is essential to increase delivery efficiency and ensure tank safety. However, predicting the boil-off rate (BOR) is not a simple task, as both experiment and calculation require a significant amount of time. In this study, a simple predictive method is developed for simulating a 1/50 scaled model tank. The method consists of steady and quasi-unsteady calculations. Steady calculations are performed to establish a correlation between LN2 level and inner-wall temperature. Quasi-unsteady calculations simulate BOG over time by changing the inner-wall boundary conditions. This method can help engineers effectively evaluate the insulation performance of a cryogenic container in a short time and provide guidelines for simulating a real scale tank.

10.1115/1.4065220

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Mixed convection model for predicting the Nusselt number of oscillating vertical plates

International Journal of Heat and Mass Transfer (2024)

Minchang Kim Taehoon Kim Hwalong You Changhyun Kim Yong-Shik Han

10.1016/j.ijheatmasstransfer.2024.126118

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Effects of the Slot Jet on the Thermal Performance of Plate Heat Sinks and the Flow Uniformity

Transactions of the Korean Society of Mechanical Engineers B (2024)

Minchang Kim Kyuhyung Do Byung-Il Choi Yong-Shik Han Hwalong You

본 연구에서는 슬롯제트 유동이 플레이트 히트싱크 열성능에 미치는 영향에 대해 분석하였다. 실험을 위해 40 × 40 mm 크기의 히터와 플레이트 히트싱크를 설치한 뒤, 윈드터널과 슬롯노즐을 통해 5, 10, 20, 30, 40 mm 폭의 슬롯제트를 형성하여 히트싱크에 분사하였다. 이 때, 히트싱크 휜 높이는 5, 10, 20 mm로 조절되었다. 히트싱크의 열성능은 윈드터널의 출구부 압력과 주변 대기압과의 차이로 산출된 압력강하량과 히터에 가해진 열량 및 히터 온도로 정의된 열저항으로 평가되었다. 실험 결과, 동일 압력강하량 대비 열저항이 최소화되는 최적 슬롯폭이 존재함이 확인되었으며, 이는 히트싱크에 충돌하는 유동이 균일해지는 지점과 일치함을 발견하였다. 또한, 최적 슬롯폭은 히트싱크 휜 높이가 높아질수록 증가하는 점을 확인하였다.

10.3795/ksme-b.2024.48.3.149

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