• Title/Summary/Keyword: 이중관 열교환기

Search Result 11, Processing Time 0.091 seconds

Design and performance analysis of water-to-air heat pump system using double-tube heat exchanger (이중관 열교환기를 사용한 물 대 공기 열펌프 시스템의 설계와 성능해석)

  • Han, D.Y.;Park, K.J.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.9 no.4
    • /
    • pp.462-471
    • /
    • 1997
  • The water-to-air heat pump system requires relatively lower energy consumption and less installation space. The heat exchangers used for this system are the finned-tube type for the indoor unit and the double-tube type for the outdoor unit. Mathematical models for this system are developed and programmed in computer. Experimental data from various conditions are obtained and compared with calculated values from the computer simulation program. Differences of cooling capacity and COP are 1.25% and 0.47%, and those of heating capacity and COP are 0.51% and 0.13%, respectively. Simulation results are in good agreement with test results. Therefore, the developed program is effectively used for the design and the performance prediction of water-to-air heat pump system.

  • PDF

Effectiveness Measurement of a Double-Tube Heat Exchanger for a Hydrogen Liquefaction System (수소액화 시스템용 이중관 열교환기의 유용도 측정)

  • Choi, H.J.;Baik, J.H.;Kang, B.H.;Choi, Y.D.
    • Transactions of the Korean hydrogen and new energy society
    • /
    • v.10 no.1
    • /
    • pp.19-26
    • /
    • 1999
  • The effectiveness of a double-tube heat exchanger has been investigated experimentally. This problem is of particular interest in the design of the heat exchanger in a hydrogen liquefaction system. Temperature, pressure, and mass flow rate for hydrogen were measured both in inner tube and in annulus of a double-tube heat exchanger. The effectiveness could be evaluated from the measured temperature and mass flow rate. It is found that the effectiveness increases with an increase in the heat transfer area of a double-tube heat exchanger and with a decrease of the heat capacity ratio. But the increase rate of the effectiveness decreased with a decrease of the heat capacity ratio. Therefore, it is presented that a criterion for selecting the heat exchanger length and heat capacity ratio to obtain the effectiveness required in a hydrogen liquefaction system.

  • PDF

A Numerical Study on Heat Transfer and Flow Characteristics of a Finned Downhole Coaxial Heat Exchanger (외부유로 내벽에 설치된 핀 형상에 따른 이중관 열교환기의 열전달 및 유동에 대한 수치해석적 연구)

  • Park, Chun Dong;Lee, Dong Hyun;Park, Byung-Sik;Choi, Jaejoon
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.41 no.2
    • /
    • pp.79-86
    • /
    • 2017
  • In this study, the flow and heat transfer characteristics of the finned annular passage were investigated numerically. The annular passage simulates co-axial geothermal heat exchanger, and fins are installed on its inner wall to reduce heat loss from the production passage (annulus) to injection passage (inner pipe). A commercial CFD program, Ansys Fluent, was used with SST $k-{\omega}$ turbulence model. The effects of the geometric parameters of the fin on the inner tube were analyzed under the periodic boundary condition. The result indicated that most parameters had a tendency to increase with an increase in the height and angle of the fin. However, it was confirmed that the Nusselt number of the inner tube on the coaxial 15, 5, 0.3 was lower than that of the smooth tube. Additionally, the Nusselt number of the inner tube exhibited a tendency of decreasing with a decrease in the spacing in Coaxial 15, $S_f$, 0.3.

Flow Characteristic with Distance of Inlet Port and Rotating Length of Fluid in the Double Heat Exchanger (이중관 열교환기의 유체 유입위치와 회전길이에 따른 유동특성)

  • Lee, Seung-Ha;Cha, Dong-An;Kwon, Oh-Kyung
    • Journal of Power System Engineering
    • /
    • v.17 no.4
    • /
    • pp.51-57
    • /
    • 2013
  • The length and position of the inlet port on the double tube heat exchanger is analyzed by CFX ver.11 for studying the characteristic of its flow distribution. When the boundary conditions of the inlet temperature and mass flow rate were each $20^{\circ}C$ and 10 ~ 50 kg/min, 3 models that are based on the distance between the inlet port and the center of the heat exchanger(0, 5.025, 10.05 mm) were analyzed to find the uniformity of the flow rate. Based on the flow rate, 4 lengths (23.723, 33.890, 44.057, 57.274 mm) were used to study the flow distribution according to Reynolds Number. The results show that, when the distance from the inlet to the position of the center of the heat exchanger is 10.05 mm and the length is 57.274 mm, the flow distribution is the most unified.

The Inprovement of the Heat Exchanger Performance by Shape Modification(I)-Experimental Analysis of the Heat Transfer Enhancement by Attached Wires in a Double Pipe Heat Exchanger- (형상변화 에 의한 열교환기 의 열전달 성능 향상 (I) -이중 동심원관내에 와이어 부착시의 열전달 촉진에 대한 실험적 해석-)

  • 노승탁;이택식;강신형;김진오
    • Transactions of the Korean Society of Mechanical Engineers
    • /
    • v.9 no.1
    • /
    • pp.71-80
    • /
    • 1985
  • The various sizes of wires are attached to the outside of the inner tube in a double pipe heat exchanger to enhance the thermal performance. The diameters of the wires range from 0.5mm to 1.6mm while the pitches are chosen between 5mm and 50mm. Experiments have been performed with the range of Reynolds numbers from 15000 to 30000 in annular space where air flows. The friction factors are increased by 1.5 to 4.5 times depending on the sizes and the pitches of the wires. However, the Nusselt numbers are increased by the factors of 1.8 to 2.8 within this experimental range. It is suggested that there should be an optimum configuration rendered when the weighting values of the heat transfer promotion and the pumping power are given.

A Fundamentals study on Heat Exchanger using Deep Ocean Water: Effects of Corrosion on Heat Transfer Performance (심층수 이용 열교환기 개발을 위한 기초연구: 열교환기 부식이 열교환기 성능에 미치는 영향)

  • Kwon, Young-Chul;Lee, Seok-Hyun;Huh, Cheol;Cho, Meang-Ik;Lee, Chang-Kyung;Kwon, Jeong-Tae
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.14 no.11
    • /
    • pp.5377-5384
    • /
    • 2013
  • This paper presents the effects of the tube materials and corrosion on the heat transfer performance of double-tube heat exchangers for the development of heat exchangers using deep sea water. Heat exchangers made of titanium, aluminum. stainless steel, iron, copper, and aluminum with electro-deposition coatings(Carbon black_$15{\mu}m$, Carbon black_$150{\mu}m$) were tested. Also, the heat transfer rate of each heat exchanger was calculated by using EES program. For the acceleration of corrosion by sea water, the temperature of sea water $70^{\circ}C$ and the concentration of salt 3.5% were considered. And the specimens were immersed in sea water during 6 weeks. From the above experiment and analysis, aluminum with electro-deposition coating(Carbon black_$150{\mu}m$) can be considered the most promising candidate for the replacement of titanium heat exchanger.

A Study of The Effect of Corrosion on Heat Transfer in a Heat Exchanger (열교환기에서 부식이 열전달에 미치는 영향에 관한 연구)

  • Kwon, Hyun-Min;Kwon, Jeong-Tae
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.20 no.9
    • /
    • pp.227-232
    • /
    • 2019
  • Heat pump systems based on ocean thermal energy conversion (OTEC) systems use the temperature difference between deep ocean water and surface ocean water to operate. However, they may have heat transfer degradation due to corrosion on the heat exchanger surface due to the salinity of sea water. This study presents experimental results for the heat transfer decrease of corroded metal tubes with respect to corrosion time. In order to replace high-priced titanium, electro-deposition (ED) coating was performed on aluminum tubes. Aluminum tubes with ED coating thicknesses of 10, 15, and $20{\mu}m$ were tested for double-tube heat exchangers after performing accelerated corrosion for 6, 12, and 18 weeks. The effects of the coating thickness and the corrosion time on the heat transfer degradation were investigated. From the results, the aluminum tube with an ED coating of $20{\mu}m$ thickness can be suggested as a candidate for replacing titanium tubes.

A Study on the Heat Transfer Perfomance of Dimpled Double Pipe Heat Exchanger on a Fuel Cell (연료전지용 딤플형 이중관열교환기의 열전달 성능에 관한 연구)

  • CHO, Dong-Hyun
    • Journal of Fisheries and Marine Sciences Education
    • /
    • v.27 no.6
    • /
    • pp.1727-1733
    • /
    • 2015
  • In the present study, the heat transfer performance of dimpled double-pipe heat exchangers for fuel cells that are utilized as cooling systems of fuel cells was studied. In addition, to comparatively analyze the heat transfer performance of dimpled double-pipe heat exchanger for fuel cells, plain double-pipe heat exchangers were also studied. Experimental results were derived on changes in the Reynolds numbers of the cooling water flowing in dimpled and plain double-pipe heat exchangers and changes in the heat flux of the air. Thereafter, to verify the reliability of the experimental results, the theoretical overall heat transfer coefficients and the experimental overall heat transfer coefficients were comparatively analyzed and the following results were derived. The heat transfer rate lost by the hot air and that of the heat transfer rate obtained by the cooling water were well balanced. The experiments of plain double-pipe heat exchangers and dimpled double-pipe heat exchangers were conducted under normal conditions and the theoretical overall heat transfer coefficient and the experimental overall heat transfer coefficient coincided well with each other. In both plain double-pipe heat exchangers and dimpled double-pipe heat exchangers, heat transfer rates increased as the cooling water flow velocity increased. Under the same experimental conditions, the heat transfer performance of dimpled double-pipe heat exchangers was shown to be higher by 1.2 times than that of plain double-pipe heat exchangers.

A Study on the Improvement of Efficiency of Heat Transfer of Double Pipe Heat Exchanger with Helical Insert Device on Cooling of a Fuel Cell (연료전지 냉각용 헬리컬 인서트디바이스 이중관열교환기의 열전달 성능 향상에 관한 연구)

  • CHO, Dong-Hyun
    • Journal of Fisheries and Marine Sciences Education
    • /
    • v.27 no.6
    • /
    • pp.1872-1879
    • /
    • 2015
  • The present study was conducted on the improvement of the heat transfer performance of double pipe heat exchangers with helical insert device. Double pipe heat exchangers with helical insert device were studied for improvement of the heat transfer performance of double pipe heat exchangers with helical insert device and plain double pipe heat exchangers were also studied to comparatively analyze heat transfer performance. Experimental results were derived on changes in the Reynold's numbers of the cooling water flowing in helical and plain double pipe heat exchangers and changes in the heat flux of the air. Thereafter, to verify the reliability of the experimental results, the theoretical total energy and the experimental total energy were comparatively analyzed and the following results were derived. The thermal energy of the calorie lost by the hot air and that of the calorie obtained by the cooling water were well balanced. The experiments of plain double pipe heat exchangers and double pipe heat exchangers with helical insert device were conducted under normal conditions and the theoretical overall heat transfer coefficient value and the experimental overall heat transfer coefficient value coincided well with each other. In both plain double pipe heat exchangers and double pipe heat exchangers with helical insert device, heat transfer rates increased as the cooling water flow velocity increased. Under the same experimental conditions, the heat transfer performance of double pipe heat exchangers with helical insert device was shown to be higher by approximately 1.5 times than that of plain double pipe heat exchangers.