• 대한기계학회논문집B
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• 제25권9호
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• pp.1149-1156
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• 2001

The objective of the present study is to investigate the performance of electronic scale mitigation unit(ESMU), which reduces the amount of scale in a heat exchanger. The circular tube with diameter of 19mm and plate-and-frame heat exchangers with 20 thermal plates were used for the tests. In order to accelerate the rate of scale in a laboratory test, artificial hard water of 1000ppm(as CaCO$_3$) was recirculated at a flow rate of 5 lpm, 7 lpm, and 9 lpm throughout the tests. The effect of ESMU on the scale thickness and overall heat transfer coefficients was examined. The test results showed that the ESMU could reduce the scale deposits even in the acceleated test.

• Journal of Advanced Marine Engineering and Technology
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• 제41권3호
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• pp.197-201
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• 2017

대부분의 어선에서는 포획된 어류를 관리하고 저장하기 위해 얼음 냉각 시스템을 사용한다. 그러나 얼음 냉각 시스템은 작동 시간의 제한뿐만 아니라 적절한 온도와 염분 농도를 유지하는 것이 어려운 단점이 있다. 본 연구의 목적은 어류 운반선의 어창에 적정한 해수온도 유지를 위한 해수 냉각 시스템용 만액식 증발 열전달 특성을 파악하는데 있다. 실험은 냉매의 해수 온도, 유량 및 포화 온도의 변화를 주며 열전달 특성을 파악하였다. 동일 열유속에서 Aluminium-Brass tube가 Copper-Nickel tube 보다 외측 열전달계수가 약 10% 큰 것으로 확인할 수 있었으며, 이를 통해 해수용 열교환기의 전열관으로 Aluminium-Brass를 적용하는 것이 열전달 측면에서 효과적일 것을 확인할 수 있었다. 만액식 단관 열전달계수와 18 kW급 만액식 해수냉각시스템의 총괄열전달계수의 비교를 통해 동일 조건에서는 25%정도 단관의 열전달계수가 큰 값을 나타내었으며, 이러한 결과는 만액식 관군 열교환기의 설계를 위한 중요한 자료가 되리라 판단된다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.144-149
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• 2006

In this study ice making characteristics are experimentally investigated for the ice slurry generating system which is pneumatically operated. The experimentations are conducted under the various test conditions such as chilled water inlet temperature, aqueous solution concentration, flow rate of cooling water, scraper pitch and frequency of cylinder stroke. For the above experimental conditions, ice making characteristics of the slurry ice generating system are evaluated in terms of the overall heat transfer coefficient, heat transfer rate and the amount of slurry ice generation. And the experimental results show that the heat transfer rate of the system increases as the flow rate of cooling water solution increases and the concentration of ethylene glycol and inlet temperature of chilled water decreases.

• 설비공학논문집
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• 제2권2호
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• pp.127-136
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• 1990

Air-solid bed has been known to be an effective heat transfer augmentation device which could be applied to heat exchangers. In this study, pressure drop and heat transfer characteristics of vertical annular fluidized bed heat exchanger with air flowing through were studied experimentally. The experiments was conducted to calculate overall heat transfer coefficient on fluidized bed heat exchangers immersed single vertical tube and investigate minimum fluidized velocity in fluidized bed of alumina beads and steel balls. The influence of flow direction, particle diameter, the heights of static bed and air mass fluidizing velocity has been examined. The experimental results showed the optimum operating condition and effective static bed height for fluidized bed heat exchangers. For the same power loss, comparisions of heat transfer effect between the fluidized bed heat exchanger and the single phase forced convetion heat exchanger indicate that both miniaturization of heat exchanger and heat transfer augmentation at low flow velocity are possible by application of the air-solid to heat exchangers.

• 대한기계학회논문집B
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• 제28권6호
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• pp.646-651
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• 2004

When the water flowing inside of the heat transfer equipments such as heat exchangers, condensers, and boilers is heated, calcium, magnesium sulfate, and other minerals in the water are deposited and built up for scales on the heat transfer surfaces. When those scales accumulate on the heat transfer surfaces, their performance of the heat transfer become progressively reduced due to the increase of the heat transfer resistance. The mechanism of this reduced heat transfer is called fouling. This study investigated the formation of the fouling in a heat exchanger with river and tap water flowed inside of it as a coolant. In order to visualize the formation of the fouling and to measure the fouling coefficients, a lab-scale heat exchanging system was used. Based on the experimental results, it was found that the formation of fouling for river water was quite different with the formation for tap water.

• 한국지열·수열에너지학회논문집
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• 제14권4호
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• pp.20-26
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• 2018

In this study, the performance characteristics of a welded plate heat exchanger was investigated experimentally. Performance tests were carried out according to the flow rate and inlet temperature of working fluid. As a result, the heat transfer capacity increased by 335.5 kW with an increasing the flow rate and temperature difference between hot and cold side. However, the overall heat transfer coefficient was increased with the increase of flow rate, and it was not effected significantly from inlet temperature difference between hot and cold working fluid. The pressure drop was increased by 55.78 kPa with an increasing the frow rate when the flow rate ratio between hot and cold side 1:1. However, the tendency of pressure drop was difference when flow rate ratio wasn't 1:1. In case that the flow rate ratio between hot and cold side was not 1:1, the pressure drop at the low flow rate side was higher than that when the flow rate ratio was 1:1, while pressure drop of the other side was decreased compared to that when the flow rate ratio was 1:1.

• 설비공학논문집
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• 제20권3호
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• pp.189-196
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• 2008

The increase of system weight due to installation of cooling devices adds electrical and mechanical loads of humanoid robot, and in return, results in much heat. Therefore, the weight of cooling system is a critical issue for robot cooling. In this study, we propose non-metallic cold plates to deal with such problems. We compare thermal performances between one metallic cold plate and five different types of non-metallic cold plates. A metallic cold plate is totally made of copper. Five non-metallic PC(polycarbonate) cold plates, which are designed to reduce the overall weight of robot cooling system, are composed of a polycarbonate cover with different types of base plate. The overall heat transfer coefficients per unit mass and thermal resistances are obtained for the cold plates. The metallic cold plate shows the best thermal performance. It is interesting to note that the PC cold plate with an aluminum base plate with 18 channels shows the best overall heat transfer coefficient per unit mass. Most polycarbonate cold plates display fairly comparable thermal performance with more reduced system weight compared to the metallic cold plate.

• 대한기계학회논문집
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• 제12권2호
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• pp.373-380
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• 1988

본 연구의 목적은 음장의 입자속도가 기류의 평균속도와 비슷한 크기인 경우에 원통으로부터 열전달의 동특성과 한 사이클의 평균값인 평균열전달이 음장에 의하여 어떠한 영향을 받는가를 구하기 위한 것이다.

• 대한설비공학회지:설비저널
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• 제16권6호
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• pp.550-559
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• 1987

• 태양에너지
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• 제8권1호
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• pp.5-12
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• 1988

One of the effective means to transfer the heat into and from the energy storage medium is thermosyphon. In this study, a two-phase closed thermosyphon with circular fins was used to extract the thermal energy stored in paraffin wax (Sunoco p-116). Heat transfer characteristics along the heat flow path were investigated as well as the overall performance. Some of the important results are as follows: (1) The temperature distribution of the wax in the radial direction was always maintained fairly uniformly; (2) Compared with bare thermosyphon, the heat transfer rate was vastly improved in the early stage of the experiment; and (3) Heat transfer coefficient between the wax and evaporating section of thermosyphon remained nearly constant during the experiment.