배플과 종횡비 통합 설계가 축열조의 열성능에 미치는 영향 = Effects of Integrated Baffle and Aspect Ratio Design on the Thermal Performance of a Thermal Storage Tank

다국어 초록 (Multilingual Abstract)

To address climate change and achieve carbon neutrality goals, improving energy-use efficiency and utilizing unused energy resources are becoming increasingly important. In particular, industrial waste heat generated from industrial processes is a valuable energy source, and reutilizing it as a heat source for heat pump systems can enhance overall system efficiency. However, a mismatch between the timing of waste-heat generation and heat-pump operation can cause an imbalance between heat supply and demand. Therefore, the design of a high-performance thermal energy storage device, namely a thermal storage tank, is required to mitigate this issue. Previous studies have mainly focused on the effects of either the aspect ratio or baffles independently, which limits a systematic understanding of the coupled interaction between these two design parameters. In this study, a sensible heat thermal storage tank was investigated, and the effects of an integrated design of the aspect ratio and baffle installation conditions on thermal stratification and mixing characteristics were analyzed using CFD simulations based on ANSYS Fluent. Numerical simulations were conducted for combinations of three aspect ratios (1, 2, 3) and three baffle numbers (0, 2, 3). To quantitatively evaluate the degree of stratification, by the Mix Number, Stratification Number, and Richardson Number. The results showed that, for larger aspect ratios (AR = 2 and 3), baffle installation contributed significantly to the formation of thermal stratification and the improvement of thermal stability. The average Stratification Number increased by approximately 5–9%, and the Richardson Number increased by 8–10%, while the Mix Number decreased by 30 –50%, indicating effective suppression of internal mixing. In contrast, for the smaller aspect ratio condition (AR = 1), the baffle effect did not increase proportionally, and excessive baffle installation could lead to performance deterioration. Although the case with up to two baffles exhibited relatively favorable performance, the three-baffle case showed a reduction of about 1% in the average Stratification Number and about 19% in the Richardson Number, along with an increase of about 35% in the Mix Number, indicating a pronounced degradation in stratification stability.

목차 (Table of Contents)

• 제 1 장 서 론 1
• 1.1 연구 배경 및 필요성 1
• 1.2 선행 연구 3
• 1.3 연구 방법 및 연구 목적 6
• 제 2 장 열저장 시스템의 이론적 고찰 7
• 2.1 축열조의 종류 7
• 2.1.1 현열 축열(Sensible Heat Storage) 방식 8
• 2.1.2 잠열 축열(Latent Heat Storage) 방식 9
• 2.1.3 화학 축열(Chemical Heat Storage) 방식 10
• 2.2 축열조의 열적 성능 평가 기준 11
• 2.2.1 믹스 수(Mix Number) 13
• 2.2.2 층화 수(Stratification Number) 15
• 2.2.3 리차드슨 수(Richardson Number) 16
• 제 3 장 축열조 열성능 시뮬레이션 18
• 3.1 열성능 시뮬레이션 조건 18
• 3.1.1 축열조의 형상(Geometry) 18
• 3.1.2 무차원 수 21
• 3.2 시뮬레이션 조건 검증(Validation) 26
• 3.2.1 선행 실험 결과와 비교 27
• 3.2.2 타임 스텝(Time Step) 밸리데이션 28
• 3.2.3 메시(Mesh) 밸리데이션 31
• 제 4 장 시뮬레이션 결과 34
• 4.1 믹스 수() 34
• 4.2 층화 수() 41
• 4.3 리차드슨 수() 47제
• 5 장 결 론 54