Download or read book Condensation of Pure Refrigerants and Refrigerant Mixtures in Smooth and Enhanced Horizontal Tubes written by Brian A. Tesene and published by . This book was released on 1998 with total page 466 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Condensation Heat Transfer in Horizontal Micro fin Tubes written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Three existing condensation heat transfer models are validated using 544 experimental data points for pure refrigerants and refrigerant mixtures. The Cavallini et al. (1999) model predicts well with the pure-refrigerant data sets. However, the Cavallini et al. (1999) model fails to predict the refrigerant-mixture data sets. The Yu and Koyama (1998) model, which is applicable for the pure refrigerants only, fails to predict most of the R22 data sets. The Kedzierski and Goncalves (1999) model, which is applicable for both pure refrigerants and refrigerant mixtures, yields relatively high mean absolute deviations for most of the pure-refrigerant data sets. The Kedzierski and Goncalves (1999) model does not account for the mass transfer thermal resistance in refrigerant mixtures. A new pure-refrigerant model and a new refrigerant-mixture semi-empirical model have been developed. Both the new models successfully predict the experimental data for pure refrigerant and for refrigerant mixtures.
Download or read book Condensation Heat Transfer in Horizontal Micro fin Tubes written by Chea-Chun Kung and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Three existing condensation heat transfer models are validated using 544 experimental data points for pure refrigerants and refrigerant mixtures. The Cavallini et al. (1999) model predicts well with the pure-refrigerant data sets. However, the Cavallini et al. (1999) model fails to predict the refrigerant-mixture data sets. The Yu and Koyama (1998) model, which is applicable for the pure refrigerants only, fails to predict most of the R22 data sets. The Kedzierski and Goncalves (1999) model, which is applicable for both pure refrigerants and refrigerant mixtures, yields relatively high mean absolute deviations for most of the pure-refrigerant data sets. The Kedzierski and Goncalves (1999) model does not account for the mass transfer thermal resistance in refrigerant mixtures. A new pure-refrigerant model and a new refrigerant-mixture semi-empirical model have been developed. Both the new models successfully predict the experimental data for pure refrigerant and for refrigerant mixtures.
Download or read book Condensation of Hydrocarbon and Zeotropic Hydrocarbon refrigerant Mixtures in Horizontal Tubes written by Jeffrey A. Milkie and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental investigation of condensation of hydrocarbons and hydrocarbon/refrigerant mixtures in horizontal tubes was conducted. Heat transfer coefficients and frictional pressure drops during condensation of a zeotropic binary mixture of R245fa and n-pentane in a 7.75 mm internal diameter round tube were measured across the entire vapor-liquid dome, for mass fluxes ranging from 150 to 600 kg m-2 s-1, and reduced pressures ranging from 0.06 to 0.23. Condensation experiments were conducted for the mixture, as well as its pure constituents over a similar range of conditions. In addition, condensing flow of the hydrocarbon propane was documented visually using high-speed video recordings. Results from these experiments were used to establish the two-phase flow regimes, void fractions, and liquid film thicknesses during condensation of propane flowing through horizontal tubes with internal diameters of 7 and 15 mm. These measurements were made over mass fluxes ranging from 75 to 450 kg m-2 s-1, operating pressures ranging from 952 to 1218 kPa, and vapor qualities ranging from 0.05 to 0.95. Liquid film thickness and void fraction data were subsequently be used to assist the development of heat transfer and pressure drop models. In particular, the heat transfer coefficients and pressure drops observed in the mixture were compared with the corresponding values for the pure constituents. Models for heat transfer and pressure drop in the pure components as well as the mixtures were developed based on the data from the present study. This work extends the available literature on two-phase flow regimes for air-water mixtures, steam, and refrigerants to include hydrocarbons. Additionally, the limited information on condensation in multi-constituent hydrocarbon-hydrocarbon and refrigerant-refrigerant mixtures was extended to include hydrocarbon-refrigerant mixtures. The findings of this study are expected to benefit applications such as refrigeration, low-grade heat-driven power generation, and the development of heat exchangers for the chemical and process industries.
Download or read book Condensation of a New Alternative Refrigerant Flowing Inside Horizontal Smooth Tubes written by Mallikarjuna S. Chitti and published by . This book was released on 1994 with total page 608 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Condensing Coefficients of the Refrigerant Mixture R 22 R 142b in Smooth Tubes and During Enhanced Heat Transfer Configurations written by Floris Jakobus Smit and published by . This book was released on 2002 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Condensation of Refrigerants Flowing Inside Smooth and Corrugated Tubes written by and published by . This book was released on 1995 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Because heat exchanger thermal performance has a direct fluence on the overall cycle performance of vapor-compression refrigeration machinery, enhanced heat transfer surfaces are of interest to improve the efficiency of heat pumps and air conditioners. We investigated R-22 and a nonazeotropic refrigerant mixture (NARM) of 75% R-143a and 25% R-124 (by mass) to study their thermal performance in a condenser made of conventional smooth tubes and another condenser made of corrugated, or spirally indented, tubes. We investigated the condensing heat transfer and pressure drop characteristics in an experimental test loop model of a domestic beat pump system employing a variable speed compressor. The refrigerant circulates inside the central tube and the water circulates in the annulus. At refrigerant mass fluxes of approximately 275--300 kg/m2s, the measured irreversible pressure drop of the corrugated surface was 23% higher than that of the smooth surface for the R-22. At refrigerant mass fluxes of 350-370 kg/m2s, the irreversible pressure drop of the corrugated surface was 36% higher than that of the smooth surface for the NARM. The average heat transfer coefficient for the corrugated surface for R-22 was roughly 40% higher than that for the smooth tube surface at refrigerant mass fluxes of 275--295 kg/m2s. The average heat transfer coefficient for the corrugated surface for the NARM was typically 70% higher than that for the smooth tube surface at refrigerant mass fluxes of 340--385 kg/m2s.
Download or read book Tubeside Condensation of Nonazeotropic Refrigerant Mixtures for Two Enhanced Surfaces written by and published by . This book was released on 1990 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: As part of the Building Equipment Research program at Oak Ridge National Laboratory (ORNL), nonazeotropic refrigerant mixtures (NARMs) are being investigated to replace chlorofluorocarbon compounds. The condensation of NARMs is not isothermal, and this can improve the heat exchanger effectiveness of a condenser as well as improve thermodynamic cycle efficiencies. The total condensing heat transfer coefficients for refrigerant R22 and for four nonazeotropic mixtures of refrigerants R143a and R124 were measured and are presented as a function of mass flux for two inside tube surfaces, one having spiral ridged fins and the other having a spirally corrugated or fluted surface. The total condensing coefficient for the finned tube is higher than that for the fluted tube at any given refrigerant mass flux for all the refrigerant mixtures. The measured irrecoverable pressure drop for the finned tube was approximately half that for the fluted tube; thus, the finned tube has the better thermal performance of the two enhanced tubes. The condensing heat transfer coefficient is also presented as a function of the mass fraction of R143a for three values of mass flux. Degradation of the condensing coefficient for intermediate values of R143a mass fraction is apparent, but has different trends with respect to mass flux for the two enhanced surfaces; thus, the geometry of the enhanced surface appears to affect the physical mechanism for condensation of NARMs. 13 refs., 9 figs.
Download or read book The Condensation of Oil refrigerant Mixtures on Single Horizontal Smooth and Finned Tubing written by Paul E. Williams and published by . This book was released on 1979 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Condensation of Refrigerants on Small Tube Bundles written by Burlin Davis Mabrey and published by . This book was released on 1988 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: The construction of an apparatus for the condensation performance testing of a horizontal bundle of four tubes with various refrigerants was completed. The apparatus was instrumented, and data reduction software was developed to provide bundle and single tube condensation data. Two tube bundles were tested, smooth copper tubes and low integral-fin copper-nickel tubes, with two refrigerants, R-114 and R-113. An enhancement ratio of about 2.0 for the overall heat transfer coefficient was demonstrated for the finned tubes over the smooth tubes. Internal contamination, possibly due to a breakdown of the refrigerant molecules when subjected to high temperatures in the boiling chamber, inhibited further meaningful data collection. Recommendations for improvement of the test apparatus are made. Condensation; Heat-transfer coefficient; Finned tubes; Enhancement ratio; Filmwise; Inundation; Tube bundle, Refrigeration systems. (jes).
Download or read book Persian Art and Architecture written by Sazman-i Jughrafiya'i Kishvar and published by . This book was released on 1973 with total page 195 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Evaporation and Condensation of a Refrigerant oil Mixtures in a Smooth Tube and a Micro fin Tube written by L. M. Schlager and published by . This book was released on 1987 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Two Phase Heat Transfer written by Mirza Mohammed Shah and published by John Wiley & Sons. This book was released on 2021-03-04 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt: A guide to two-phase heat transfer theory, practice, and applications Designed primarily as a practical resource for design and development engineers, Two-Phase Heat Transfer contains the theories and methods of two-phase heat transfer that are solution oriented. Written in a clear and concise manner, the book includes information on physical phenomena, experimental data, theoretical solutions, and empirical correlations. A very wide range of real-world applications and formulas/correlations for them are presented. The two-phase heat transfer systems covered in the book include boiling, condensation, gas-liquid mixtures, and gas-solid mixtures. The authora noted expert in this fieldalso reviews the numerous applications of two-phase heat transfer such as heat exchangers in refrigeration and air conditioning, conventional and nuclear power generation, solar power plants, aeronautics, chemical processes, petroleum industry, and more. Special attention is given to heat exchangers using mini-channels which are being increasingly used in a variety of applications. This important book: Offers a practical guide to two-phase heat transfer Includes clear guidance for design professionals by identifying the best available predictive techniques Reviews the extensive literature on heat transfer in two-phase systems Presents information to aid in the design and analysis of heat exchangers. Written for students and research, design, and development engineers, Two-Phase Heat Transfer is a comprehensive volume that covers the theory, methods, and applications of two-phase heat transfer.
Download or read book Vapor Compression Heat Pumps with Refrigerant Mixtures written by Reinhard Radermacher and published by CRC Press. This book was released on 2005-06-23 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: Amidst tightening requirements for eliminating CFC's, HCFC's, halons, and HFC's from use in air conditioning and heat pumps, the search began for replacements that are environmentally benign, non-flammable, and similar to the banned refrigerants in system-level behavior. Refrigerant mixtures are increasingly used as working fluids because they demo
Download or read book Condensation of Refrigerant 11 on the Outside of Vertical Enhanced Tubes written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Experiments were conducted to determine heat transfer performance of single vertical tubes with Refrigerant-11 condensing on its outside surface. Twelve enhanced (fluted, spiraled, roped, and corrugated) tubes of 2.54-cm (1-in.) nominal outside diameter and 1.2-m (4-ft) length were tested. Several of the tested tubes featured internal enhanced geometries. A previously tested smooth tube served as the basis for comparison. Composite heat transfer coefficients (coefficients that include the resistances of both the condensing film and the tube wall), based on the total tube outside surface area, ranged from 850 to 6530 W/m/sup 2/ . K (150 to 1150 Btu/h . ft/sup 2/ . /sup 0/F) over the heat flux range of 5675 to 31,375 W/m/sup 2/ (1800 to 9950 Btu/h . ft/sup 2/). The primary conclusions from this study are: (1) for a given heat flux, an external fluted tube can increase composite condensing heat transfer coefficients by up to 5.5 times the smooth tube values, giving better condensing performance than any of the other geometries tested; (2) further increase in composite condensing coefficients can be achieved by using skirts to divide the fluted tube into equal condensing lengths; and (3) for a given overall temperature difference and water flow rate, internal flutes can increase the overall performance by up to 17% over that for a tube with identical outside flutes and a smooth inside surface.
Download or read book Condensation Heat Transfer Measurements of Refrigerants on Externally Enhanced Tubes written by David S. Zebrowski and published by . This book was released on 1987 with total page 149 pages. Available in PDF, EPUB and Kindle. Book excerpt: An apparatus was designed and fabricated for testing of a horizontal bundle of five tubes in a vertical row with R-114 as the working fluid. Twenty-four tubes with rectangular-section fins ansd a smooth tube were tested in a single-tube apparatus using R-113 as the working fluid. An enhancement ratio (based on constant vapor-side temperature drop) of about 7.0 was obtained for the best-performing tube. Among the tubes tested, the optimum fin spacing was found to be between 0.25 mm to 0.5 mm. The optimum fin thickness for tubes with a 1.0 mm fin height was found to be 0.5 mm. The vapor-side enhancement ratio increased with increasing fin height. However, the rate of increase in the vapor-side enhancement was found to be smaller with increasing fin height compared to the rate of area increase. The indirect measurement of the local condensing heat-transfer coefficient around a finned tube showed a local value at the top of each of the two tubes tested that is approximately twice the average value for the entire tube.
Download or read book A Review on Condensation Process of Refrigerants in Horizontal Microfin Tubes written by Thanh Nhan Phan and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heat transfer performance of refrigerant on the condensation process is very important in the designing of condensation equipment, especially in air conditioning and refrigeration systems. The outstanding advantages of microfin tubes are reducing the weight and size of condensers and also reducing the amount of refrigerant on the system. Reviewing the general concept of condensation and detailing the formation of flow pattern map that is also the procedure to determine heat transfer coefficient and pressure drop during condensation process of refrigerant inside the horizontal microfin tubes would be considered. Also, a typical example will be presented to illustrate a detailed procedure to calculate the value of heat transfer coefficient and pressure drop during the condensation process in horizontal microfin tubes. The data results show that microfin tube J60 with 60 number of fins inside 8.96 mm inner diameter, 0.2 mm height of fin, 40o of apex angle and 18o of helix angle, the condensation procedure of R1234ze at 35°C, heat flux of 8.62 kW/m2, and mass flux of 222 kg/m2s that could be estimated with heat transfer coefficient would be reduced from 8160.4 [W/m2 K] to 1413.8 [W/m2 K] follow with quality x changes from 0.99 to 0.01, and the maximum pressure drop of this process is 3173.8 [Pa/m].
