• 한국자동차공학회논문집
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• 제18권2호
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• pp.135-140
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• 2010

An important goal in diesel engine research is the development of a means to reduce the emissions of nitrogen oxides (NOX). The use of a cooled exhaust gas recirculation (EGR) system is one of the most effective techniques currently available for reducing nitrogen oxides. Since Particular Matter (PM) fouling reduces the efficiency of an EGR cooler, a trade-off exists between the amount of NOX and PM emissions, especially at high engine loads. In the present study, engine dynamometer experiments have been performed to investigate the heat exchange characteristics of the stack-type EGR coolers with wave fin pitches of 3.6 and 4.6 mm. The results show that the heat exchange effectiveness is decreased as surface area decrease with pitch of 4.6 mm due to PM fouling. As surface area increase at pitch of 3.6 mm, super-cooling happens in the recirculated exhaust gas.

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 2003년도 International Symposium on Clean Environment
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• pp.165-170
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• 2003

A significant surface net heat loss appears around the Kuroshio and the Tsushima Warm Current regions. The area where the surface heat loss occurs should require heat to be supplied by the current to maintain the long-term annual heat balance. Oceanic heat advection in these regions plays an important role in the heat budget. The spatial distribution of the heat supply by the Tsushima Warm Current near the surface was examined by calculating the horizontal heat supply in the surface layer of the East/Japan Sea, directly from historical sea surface temperature and current data. We have also found a simple estimation of the effective vertical scale of heat supply by the current to compensate net heat loss using the heat supplied by the current in the surface 10m layer. The heat supplied by the current for the annual heat balance was large in the Korea/Tsushima Strait and along the Japanese Coast, and was small in the northwestern part of the East/Japan Sea. The amount of heat supplied by the current was large in the northwestern part and small in the southeastern part of the East/Japan Sea. These features suggest that the heat supplied by the Tsushima Warm Current is restricted to near the surface around the northeastern part and extends to a deeper layer around the southeastern part of the East/Japan Sea.

• KIEAE Journal
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• 제14권4호
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• pp.127-131
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• 2014

The ground source heat pump (GSHP) system is a kind of the temperature differential energy system using relatively stable underground temperature as heat source of space heating and cooling. This system can achieve higher performance of system than it of conventional air source heat pump systems. However, its superiority of the system performance is different according to installation location or local climate, because the system performance depends on the underground condition which is decided by annual average air temperature. In this study, in order to estimate the feasibility of the ground source heat pump system according to the local climate, numerical simulation was conducted using the ground heat transfer model and the surface heat balance model. The case study was conducted in the condition of Seoul, Daejeon, and Busan, In the result, the heat exchange rate of Busan was 34.33 W/m as the largest in heating season and it of Seoul was 40.61 W/m as the largest in cooling.

• 한국농림기상학회:학술대회논문집
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• 한국농림기상학회 2003년도 춘계 학술발표논문집
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• pp.58-61
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• 2003

A land surface parameterization has been used to simulate influences of the terrestrial surface on the atmosphere. A simple biosphere model (SiB2), one of land surface parameterization, calculates exchange of radiation, sensible heat, latent heat, and momentum between the surface and the atmosphere (Sellers, et al., 1996).(omitted)

• 생물환경조절학회지
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• 제12권3호
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• pp.107-113
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• 2003

본 연구에서는 온실의 온풍식 난방시스템 연통에 장착할 수 있는 폐열 회수기의 성능 개선을 목적으로 기 설계된 세 가지 열교환 장치와 기존의 장치에서 열교환 면적과 파이프의 두께 및 공기흐름 방향을 개량한 새 열교환 장치에 대해 열회수 성능을 실험적으로 비교 분석하였다. 그 결과 기존의 열 교환장치인 A형, B형 및 C형의 열회수 성능은 동일 송풍전입에서 각각 42.2%, 40.6% 및 54.4% 정도였으나 , 새로 개량된 D형은 69.2%로써 가장 현저히 높게 나타났다. 그러나 열회수용 공기의 흐름방향 변화에 따른 열회수 성능 개선효과 (A형 대비 B형)는 없는 것으로 나타나 적정 송풍기 용량이라면 직선형이 공기의 흐름방향 180${\circ}C$ 굴절시키는 헤어핀형보다 효과적인 것으로 판단된다. 결국 열회수 성능은 열회수 시스템의 열교환 면적과 열교환 파이프의 두께 및 풍속에 크게 좌우되는 것으로 나타났다. 따라서, 열교환 파이프의 내구성 등 을 고려하여 기능한 한 범위 내에서 열 교환면적을 증대시키거나 열교환 파이프의 두께를 앓게 하고 풍속을 증대시키는 것이 열회수 성능 개선효과와 직결됨을 알 수 있었다. 그리고 송풍기 용량이 필요이상으로 큰 경우, 소비전력이 많게 되는 등의 문제가 있기 때문에 적정용량 및 제품의 안정성을 고려하여 선택해야 할 것으로 판단되었다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2007년도 추계학술대회 논문집
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• pp.20-20
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• 2007

• 한국산업융합학회 논문집
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• 제7권4호
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• pp.331-340
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• 2004

This paper presents a feasibility study of a fresh air load reduction system by using an underground double floor space. The fresh air is introduced into the double slab space and passes through the opening bored into the footing beam. The air is cooled by the heat exchange with the inside surface of the double slab space in summer, and heated in winter. This system not only reduces sensible heat load of the fresh air by heat exchange with earth but also reduces latent heat load of the fresh air by ad/de-sorption of underground double slab concrete. In this paper, we used a model for evaluation of fresh air latent heat load reduction by hygroscopic of air to earth exchange system taking into account coupled heat and moisture transfer of underground double floor space. In conclusion it shows the validity of the proposed method for a design tool and the quantitative effect of the system.

• 설비공학논문집
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• 제25권8호
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• pp.427-431
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• 2013

Ground heat pump systems utilize the annually stable underground temperature to supply heat for space heating and cooling. The underground temperature affects not only the underground ecosystem, but also the performance of these systems. However, in spite of the widespread use of these systems, there have been few researches on the effect of the systems on underground temperature. In this research, case studies with numerical simulation have been conducted, in order to estimate the effect of ground heat pump systems on underground temperature. The simulation was coupled with the ground water-ground heat transfer model and the ground surface heat transfer model. In the result, it was found that the underground change depends on the heat transfer from the ground surface, the heat exchange rate, and the heat conductivity of soil.

• 한국지열·수열에너지학회논문집
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• 제19권3호
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• pp.1-13
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• 2023

Hydronic heated road pavement (HHP) systems have been well established and documented to provide road safety in winter season over the past two decades. However, most of the systems run on asphalt, only a few are tested with concrete, and there rarely is a comparison between those two common road materials in their performance. The aim of this study is to investigate the thermal performance of the concrete HHP systems, including surface temperature variations of experimental pavements in winter season. For preliminary study a small-scale experimental system was installed to evaluate the heat transfer characteristics of the concrete HHP in the test field. The system consists of 3 concrete slabs made of 1 m in width, 1 m in length, and 0.25 m in height. In these slabs, circulating water piping was embedded with different pipe depths of 0.08 m (Case A), 0.12 m (Case B), and 0.20 m (Case C) and same horizontal space of 0.16 m. Heating performance in winter season was tested with different inlet temperatures of 25℃, 30℃, 35℃ and 40℃ during the entire measurement period. Overall, the surface temperature of the concrete HHPs remained above 3℃ in all experimental conditions applied in this study. The results of the surface temperature measurement with respect to the pipe depth showed that Case B was the highest among the three cases. However, the closer the circulating water pipe was to the pavement surface, the greater the heat exchange rate. This results is considered that the heat is continuously accumulated inside the pavements and then the temperature inside the pavements increases, while the amount of heat dissipation decreases as the temperature difference between the inlet and outlet of circulating water decreases. In this preliminary test the applicability of the concrete HHP on road deicing was confirmed. Finally, the results can be used as a basis for studying the effects of various variables on road pavements through numerical analysis and for conducting large-scale empirical experiments.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 2002년도 춘계 학술발표회 논문집
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• pp.21-27
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• 2002

Catalytic combustor with heat exchangers are often employed in process technology where a compact design is required [1]. The use of fin and tube heat exchanger offers the enhanced surface area for heat exchange. The recent progress and performance of the fin-tube heat exchanger, especially airside, has been reviewed extensively by Wang[2].(Omitted)