• Applied Chemistry for Engineering
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• v.30 no.5
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• pp.523-529
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• 2019

In this study, we investigated the pretreatment technologies of volatile organic compounds (VOCs) which is a problem as the semiconductor and display industry develops recently. The conventional concentrator used in the direct combustion system, is easily contaminated by the exhaust gas in the manufacturing process of the display, resulting in the low treatment efficiency of generated VOCs. Physical/Chemical analyses of the exhaust gas showed high boiling point and viscosity in addition to a large amount of molecular weight alcohols and oil components. In this study, we tried to treat degrading materials by using the heat exchanger in a pretreatment facility and some materials degrading the concentrator were condensed more than 90%. In addition, it was also confirmed that an auxiliary device of the grease filter could remove the redispersion polymer oil from the heat exchanger.

• Journal of the Korean Geotechnical Society
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• v.30 no.4
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• pp.93-99
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• 2014

Use of geothermal energy has been increased for its economical application and environmentally friendly utilization. Particularly, for energy piles, a spiral coil type ground heat exchanger (GHE) is more preferred than line type GHEs such as U and W shaped GHEs. A PHC energy pile with spiral coil type GHE was installed in an area of partially saturated dredged soil deposit, and a thermal response test (TRT) was conducted for 240 hours under a continuous operation condition. Besides, remolded soil samples from different layers were collected in the field, and soil specimens were reconstructed according to the field ground condition. Non-steady state probe methods were conducted in the lab, and ground thermal conductivity and thermal diffusivity were measured for the different soil layers. An equivalent ground thermal conductivity was calculated from the lab test results and it was compared with the field TRT result. The difference was less than 5%, which advocates the use of an equivalent ground thermal conductivity for the multi-layered ground. Furthermore, this paper also represents an equivalent ground thermal diffusivity evaluation method which is another very important design parameter.

• Journal of the Korean Geotechnical Society
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• v.24 no.1
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• pp.37-49
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• 2008

A geothermal heat pump system is a preferable alternative energy system in Korea because it uses the heat energy of the earth, which is environmentally friendly and inexhaustible. In order to characterize the thermal conductivity and viscosity of grout materials used for backfilling ground heat exchangers, nine bentonite grouts, one marine clay from Boryung, and cement grouts adapted in the United State have been considered in this study. The bentonite grouts indicate that the thermal conductivity and viscosity increase with the content of bentonite or filler (silica sand). In addition, material segregation can be observed when the viscosity of grout is relatively low. The marine clay turns out to be unsuitable for backfilling the ground heat exchanger due to its insufficient swelling potential. The saturated cement grouts appear to possess much higher thermal conductivity than the saturated bentonite grouts, and the reduction of thermal conductivity in the cement grouts after drying specimens is less than that in the case of the bentonite grouts. Maintaining the moisture content of grouts is a crucial factor in enhancing the efficiency of ground heat exchangers.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.1
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• pp.9-15
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• 2013

The effective use and management of energy resources has been issued to solve the global warming problem and petrolium price increase. To improve the energy efficiency of a heat exchanger, a new countermeasure is required and the heat transfer research of nano-fluids as a new working fluid is needed. This study was carried out with increasing the Reynolds number and the vol% of nano-fluids in the inlet temperature of $25^{\circ}C$ and $50^{\circ}C$. As the result, the higher the entrance temperature is, the higher the convective heat transfer coefficient is.

• Transactions of the Korean Society of Mechanical Engineers
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• v.1 no.3
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• pp.156-163
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• 1977

길이방향의 열전도효과가 비교적 큰유체- 고체 열교환계내에 일정한 조ㅍ은 온도를 가진 유체가 유입될 때 이에 따른 비정상 온도분포가 해석되었다. 이러한 계를 기술하는 연립편미분 방정식의 수치해가 유한차분법에 의해 구해졌으며, 열전도가 무시된 경우에 대한 해석적 해를 구하여 위의 결과를 검증하였다. 한편 이상화된 모델에 대한 실험을 행하고 이 결과를 앞서 구한 수치해와 비교 검토하였다. 여기서 구해진 온도분포를 이용하여 축열효율${\eta}_A$및 ${\eta}_B$를 ${\eta}_A$는 시간 t에서의 축열량과 정상상태에 도달했을 때의 축열량의 비로 , 그리고 ${\eta}_B$는 시간 t 동안의 축열된 양과 공급된 열량의 비고 정의하여 온도분포와 효율들에 애하여 시간변수 .tau., 위치변수 .xi.와 무차원 열확산율 .betha.가 미치는 영향을 조사하였다. 이에 따르면 온도는 .betha. 가 적어짐에 따라 점점 가파르게 분포되고 한편 ${\eta}_A$는 .tau.가 점점 커지거나, .xi.가 작아질수록 좋아지는 것을 알 수 있다. 또한 ${\eta}_B$는${\eta}_A$와는 정반대의 경향을 보여주어 축열계의 최적상태가 존재함을 알 수 있다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.12
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• pp.875-880
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• 2012

The field of the large volume heat exchanger for wasted heat recovery ventilation system is being expanded enormously seeing as the fact that the quantity of reducing energies are huge due to the large volume heat exchanger for wasted heat recovery system at large buildings and factories, which consume large amount of energies while it has been arising huge amount of losses in Korea because of the lack of technology. To develop large volume waste heat recovery heat exchanger, rotor type heat exchanger was simulated for the surface corrugation. Based on the simulation results produced $30,000m^3/h$ grade waste heat recovery, heat exchanger was performed for the actual experiment. In addition, performance tests exceed the capacity of a large waste heat recovery heat exchanger performance test methods proposed.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.17 no.3
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• pp.13-20
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• 2021

The capacity optimization of the heat exchanger of the TEM dehumidifier was performed through numerical analysis. If the ratio of the size of heat exchangers on the cold and hot surfaces of the TEM is not appropriate, the larger the size of the heat exchanger results the lower performance and efficiency. Optimizing the ratio of heat exchangers on the cold surface of TEM can improve the performance and the efficiency compared to when the ratio is 50%. The optimal proportion of cold surface heat exchangers is inversely proportional to the sum of the size of the heat exchangers on the cold and hot surfaces. When the optimum ratio of cold surface heat exchanger was applied, the larger the sum of size of the two heat exchangers results the greater the improvement of the performance and efficiency, compared to when the ratio of cold surface heat exchangers is 50%.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.5
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• pp.415-421
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• 2012

Stirling engine is an external combustion engine, whose efficiency approaches that of Carnot engine with the help of a regenerator. The regenerator is a heat exchanger composed of porous medium, whose performance is dependent on the pore structure. Three types of pore structures are considered in the present study. They are wire screen, random wire and composite structure, i.e. a combination of wire screens with different hydraulic diameters. The porosity more highly affects the performance of a regenerator compared to the hydraulic diameter. The random wire can yield high effectiveness even at a high porosity. The composite mesh gives better performance when the hydraulic diameter decreases in the direction from hot side to cold side.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.5
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• pp.1276-1293
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• 1993

A numerical and experimental flow visualization study of the louvered fin array, commonly used in a compact heat exchanger was performed. The flow structure which was obtained by using a finite difference method, was compared with an experimental result. The experimental flow visualization was performed by using a dye injection technique with 13:1 scale model. The effects of Reynolds number and fin geometries on flow structure and heat transfer were examined.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2000.11a
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• pp.193-198
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• 2000

분무건조장치는 Solution, Slurry, Emulsion, Colloidal Suspension 등의 액상원료를 미립화하여 표면적을 증가시켜 수열면적을 크게 하여 열풍과 직접 접촉함으로써 순간적으로 건조를 행하여 액상원료로부터 바로 분립상의 제품을 얻는 건조법이다. 분유를 비롯하여 Instant 식품류, 합성세제, 염료, 안료, Ceramic, 공해 폐액의 처리에 이르기까지 폭넓게 이용되고 있다. 분무건조기는 통기, 회전, 기류 건조기 등 다른 건조기에 비하여 고도의 설계 및 제작 기술을 요하며, 설계에 있어서 일부 이론적인 취급이 행해지고 있는 것은 사실이나 아직은 경험에 의존하고 있는 현실이다. 국내에서 제작되고 있는 분무건조기의 열효율은 25-33%로 선진국의 35-48%에 비해 매우 낮다. 국내에서 사용되고 있는 분무건조기의 92%는 덴마크, 일본 등에서 수입된 것이다.(중략)