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수직 Multi-Flat Tubes가 잠열 저장 시스템의 방열과정에 미치는 영향 평가
김혁규(Hyeukgyu Kim),박성현(Sung Hyun Park),이동현(Dong Hyun Lee),홍성국(Sung Kook Hong),김범석(Beom Seok Kim) 대한기계학회 2023 대한기계학회 춘추학술대회 Vol.2023 No.11
Latent heat thermal energy storage system (LHTES) has emerged as a solution to address the imbalance between energy demand and supply. Efficient charging techniques for LHTES are gaining traction, particularly in mitigating the challenges posed by the low thermal conductivity of phase change materials. This study focuses on investigating the impact of solidification during the discharging process in LHTES, specifically when utilizing vertical multi-flat tubes, and assesses the effect of varying flow rates through transient 3D numerical analysis. The LHTES system comprises a phase change material (RT64HC) and multi-flat tubes arranged in a 4×12 configuration with equidistant spacing. Through numerical analysis, we observe an asymmetric transient transition of the phase change material when utilizing flat tubes. Furthermore, our results demonstrate a negative influence on LHTES discharging with increased flow rates. These findings provide valuable insights for the design and optimization of LHTES systems, contributing to more efficient energy storage solutions.
전기자동차용 50 kW 변압기의 설계를 위한 전자기-열 수치해석 파라미터 연구
김혁규(Hyeukgyu Kim),박성현(Sung Hyun Park),설현수(Hyun-Soo Seol),유준열(Jun-Yeol Ryu),박준성(Junsung Park),김범석(Beom Seok Kim) 대한기계학회 2024 大韓機械學會論文集B Vol.48 No.3
The transformer is a crucial component in the power conversion circuit of electric vehicles. Given the spatial constraints within electric vehicles, the transformer design must be compact while maintaining the required inductance and thermal stability. In this study, we explore volume reduction strategies for a 50 kW transformer while ensuring an optimal cooling design using an electromagnetic–thermal numerical analysis. The transformer cooling mechanism featured a molding housing that encapsulated the transformer, complemented by convective cooling channels. Our numerical methodologies were validated with experimental results. Through this approach, we achieved a 36.2% volume reduction in the transformer within the desired operating range of inductance. Moreover, our findings revealed that, despite a higher electromagnetic loss, an aluminum housing significantly outperformed bakelite housing in heat dissipation. Based on this investigation, we suggest design guidelines for transformers intended for future electric vehicles.
전력 변환 시스템용 방열판의 방열 특성 개선을 위한 수치해석적 파라미터 연구
박성현(Sung Hyun Park),권민호(Minho Kwon),제갈준혁(Junhyeok Jegal),김혁규(Hyeukgyu Kim),김범석(Beom Seok Kim) 대한기계학회 2023 대한기계학회 춘추학술대회 Vol.2023 No.11
GaN device play a critical role in Power Conversion Systems (PCS) by modulating electrical signals to regulate current flow. Recently, the miniaturization of GaN MOSFETs within PCS has led to excessive heat generation per unit volume, which causes a rise in temperature. The increased temperature damages the GaN device and decline its electrical performance. In this study, we evaluate the thermal dissipation performance of GaN device heatsink through numerical analysis. We conducted 3D steady-state conjugated heat transfer simulations by using the ANSYS Fluent. We analyzed the impact on local temperature and pressure drop by conducting a parametric study on the fans flow rate, fin spacing. In our research, we verified the trade-off relationship between heatsink cooling performance and pressure drop. This study is expected to provide guidance for the optimal design of heatsinks, making a significant contribution to the field of heat transfer.