• Title/Summary/Keyword: Condensation heat transfer

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The Condensation Pressure Drop of R-22 and R-410A in Small Diameter Tube (세관내 R-22와 R-410A의 응축 압력강하)

  • Son, Chang-Hyo
    • Journal of Hydrogen and New Energy
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    • v.19 no.2
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    • pp.156-162
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    • 2008

  • The condensation pressure drop for R-22 and R-410A flowing in a small diameter tube was investigated. The test section is a counterflow heat exchanger with refrigerant flowing in the inner tube and coolant flowing in the annulus. The test section consists of 1220 mm length with horizontal copper tube of 3.38 mm outer diameter and 1.77 mm inner diameter. The refrigerant mass fluxes ranged from 450 to $1050\;kg/m^2{\cdot}s$ and the average inlet and outlet qualities were 0.05 and 0.95, respectively. The main experimental results were summarized as follows : In the case of two-phase flow, the pressure drop increases with increasing mass flux and decreasing quality. The pressure drop of R-22 is slightly higher than that of R-410A for the same mass flux. Most of correlations proposed in the large diameter tube showed enormous deviations with experimental data.

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Performance Prediction of Heat Exchanger for Waste Heat Recovery from Humid Flue Gases (습증기를 포함한 연소가스의 폐열회수를 위한 열교환기 성능 예측)

  • Jeong, Dong-Woon;Lee, Sang-Yong;Lee, Han-Ju
    • Proceedings of the KSME Conference
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    • 2000.04b
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    • pp.276-281
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    • 2000

  • A simulation program using the mass transfer correlation was constructed to analyze 1-D simplified condensing flow across the tube bank. Higher efficiency was anticipated by reducing the flue gas temperature down below the dew point where the water vapor in the flue gas is condensed at the surface of the heat exchanger; that is, the heat transfer by the latent heat is added to that by the sensible heat. Thus, there can be an optimum operating condition to maximize the heat recovery from the flue gas. The temperature rises of the flue gas and the cooling water between the inlet and the outlet of the tube bank were compared with the experimental data reported previously. The predicted results agree well with the experimental data. Using this simulation program, the parametric studies have been conducted fur various operating conditions, such as the velocities and temperatures of the vapor/gas mixture and the cooling water, the number of the rows, and the conductivity of the wall material.

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A Study on the Performance of the Heat Transfer for the Liquid Filling as the Ratio of Working Fluid Volume to Total Volume of the Thermosyphon with Axial Internal Fins (축방향 내부 핀을 가진 열사이폰의 작동유체 체적변화에 대한 열전달 성능에 관한 연구)

  • Lee, Jung-Han;Lee, Ki-Baik;Cho, Dong-Hyun
    • Journal of the Korean Solar Energy Society
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    • v.22 no.1
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    • pp.23-30
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    • 2002

  • This study concerns the performance of the heat transfer of the thermosyphon having 80 internal fins in which boiling and condensation occur. Water has been used as the working fluid. The Liquid filling as the ratio of working fluid volume to total volume of thermosyphon have been used as the experimental parameters. The heat flux and heat transfer coefficient at the condenser are estimated from the experimental results. The experimental results have been assessed and compared with existing theories. As a result of the experimental investigation we can state that the maximum heat flow rate in the thermosyphon prove to depend upon the liquid fill quantity. The relatively high rates of heat transfer have been achived operating in the thermosyphon with axial internal fins. Also, the thermosyphon with internal micro fins can be used to achieve some inexpensive and compact heat exchangers in low temperature. In addition, it is to obtain the overall heat transfer coefficients and the characteristics as a operating temperature for the practical applications.

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Simulation for High Efficient Heat Pump System using Seawater Heat Source and Exhaust Energy (해수 열원 및 폐열 이용 고성능 열펌프 시스템 모사)

  • 최광일;오종택;오후규
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.15 no.1
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    • pp.59-66
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    • 2003

  • The purpose of this study is to analyze the characteristics (COP) of the heat pump system for various operating conditions with the use of seawater heat source and exhaust energy. To accomplish the goal, first of all, the computer simulation for heat pump system is carried out. The heat pump system model is made of a waste heat recovery system and a vapor compression refrigeration system, and the working fluid is R-22. The model calculated the change of COP with the variation of temperature and flow rate. The COP and the plate heat exchanger (PHE) area of the heat pump system are considered moderately high in the condensation temperature of $25^{\circ}^C$ and the evaporation temperature of $2^{\circ}^C$ in indoor culture system. The simulation results will be used effectively for the design and the performance prediction of heat pump system using unused energy in a land base aquaculture system.

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