Download or read book An Experimental Study of Filmwise Condensation on Horizontal Enhanced Condenser Tubing written by Huseyin Ciftci and published by . This book was released on 1979 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heat transfer and hydrodynamic performance of eight different geometrically enhanced tubes of different metals was determined. Results were compared to a 25.4 mm (1.0 in.) OD, smooth stainless steel tube. Steam at about 21 kPa (3 psia) was condensed on the outside surface of each enhanced tube, horizontally mounted in the center of a dummy tube Bank. Each tube was cooled on the inside by water. The overall heat transfer coefficient was determined directly from experimental data. The inside and outside heat transfer coefficients were determined using the Wilson plot technique. The cooling water pressure drop was measured inside the tube and converted to the friction factor in the enhanced section. The overall heat transfer coefficients of the enhanced tubes were increased as much as 1.9 times, and the corrected pressure drops of the enhanced tubes were as large as 4 times the corresponding smooth tube value for the same cooling water velocity. The helix angle should be 45 deg to 60 deg on the inside surface and 90 deg on the outside surface of the tube to obtain maximum inside and outside heat transfer coefficients. (Author).

Download or read book An Experimental Study of Filmwise Condensation on Horizontal Enhanced Condenser Tubing written by and published by . This book was released on 1979 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heat transfer and hydrodynamic performance of eight different geometrically enhanced tubes of different metals was determined. Results were compared to a 25.4 mm (1.0 in.) OD, smooth stainless steel tube. Steam at about 21 kPa (3 psia) was condensed on the outside surface of each enhanced tube, horizontally mounted in the center of a dummy tube Bank. Each tube was cooled on the inside by water. The overall heat transfer coefficient was determined directly from experimental data. The inside and outside heat transfer coefficients were determined using the Wilson plot technique. The cooling water pressure drop was measured inside the tube and converted to the friction factor in the enhanced section. The overall heat transfer coefficients of the enhanced tubes were increased as much as 1.9 times, and the corrected pressure drops of the enhanced tubes were as large as 4 times the corresponding smooth tube value for the same cooling water velocity. The helix angle should be 45 deg to 60 deg on the inside surface and 90 deg on the outside surface of the tube to obtain maximum inside and outside heat transfer coefficients. (Author).

Download or read book An Experimental Study of Dropwise Condensation on Horizontal Condenser Tubes written by John Talbot Manvel (Jr) and published by . This book was released on 1979 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: Three types of drop promoting coatings were applied to the outside of 15.9 mm (5/8 in) outside-diameter condenser tubes to determine their effect on heat transfer performance. The coatings included a new fluorolepoxy, a commercial series of fluorocarbon coatings, and sputtered TFE. Coating thickness varied from 0.02 to 12.7 microns. Steam at about 21 KPa (3 psia) was condensed on the outside surface of each coated tube. Each test tube was cooled on the inside by water at velocities of 0.80 to 7.60 m/sec (3 to 25 ft/sec). The overall heat transfer coefficient was determined directly from experimental data. The inside and outside heat transfer coefficients were determined by using the Wilson Plot technique. Of the commercial fluorocarbon coatings, the 'Nedox' coating on a copper-nickel tube enhanced the outside heat transfer coefficient by 53% and improved the corrected overall heat transfer coefficient by 27%. Of the sputtered TFE coated tubes, the 0.08-micron thick coating on a copper-nickel tube enhanced the outside heat transfer coefficient by 45% and improved the corrected overall heat transfer coefficient by 21%.

Download or read book An Experimental Study of Steam Condensation on a Single Horizontal Tube written by Derry Thomas Pence and published by . This book was released on 1978 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental test facility capable of investigating plain and enhanced horizontal tubes was built. The test facility consists of an electric boiler, test condenser and associated piping for steam, condensate and cooling water. Performance of the test condenser was checked at a steam pressure of 3 psia with cooling water velocities ranging from 5 to 25 ft/sec. Condensation data was obtained for a single, 0.625 inch outside diameter, 90-10 copper-nickel tube in a simualted tube bundle to determine the overall, inside and outside heat transfer coefficients. The overall heat transfer coefficient was determined directly from experimental data, and the Wilson Plot technique was used to determine the inside and outside heat transfer coefficients. The experimentally obtained values for the inside heat transfer coefficient are within 5 percent of the theoretical values predicted by the Sieder-Tate equation. The experimental values obtained for the outside heat transfer coefficient are within 8 percent of the theoretical values predicted by the Nusselt equation. (Author).

Download or read book An Experimental Study of Dropwise Condensation on Horizontal Condenser Tubes written by John Talbot Manvel and published by . This book was released on 1979 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Experimental Investigation of Enhanced Heat Transfer on Horizontal Condenser Tubes written by David J. Reilly and published by . This book was released on 1978 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heat transfer and hydrodynamic performance of three different spirally fluted tubes was determined. The tubes were 5/8-in. in nominal diameter and were made of aluminum. Results were compared to 5/8.in. OD, smooth copper-nickel and aluminum tubes. Data was taken by condensing steam at about 3 psia on the outside surface of a horizontally mounted tube in the center of a tube bank. The center tube was cooled by water on the inside at velocities of 3 to 25 feet per second. The overall heat transfer coefficient was determined directly from experimental data. The inside and outside heat transfer coefficients were determined using the Wilson plot technique. The cooling water pressure drop was measured inside the tube and converted to the friction factor in the enhanced section. The overall heat transfer coefficients of the enhanced tubes were as large as 1.75 times the corresponding smooth tube value for the same mass flow rate of cooling water. The inside heat transfer coefficients increased by about a factor of 3 while the outside heat transfer coefficients decreased by 10 to 20 percent when compared to smooth tube values. The results of this work indicate that the required condenser surface area can be reduced by 50 percent if these enhanced tubes are used in place of smooth tubes. (Author).

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental Study of Laminar Film Condensation on Bank of Horizontal Tubes with Stefan Number Greater Than Unity written by R. K. Sharma and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Film Condensation of Steam on Externally Finned Horizontal Tubes written by and published by . This book was released on 1985 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Filmwise condensation measurements of steam were made on horizontal finned tubes under vacuum and near-atmospheric conditions. Data were obtained for copper tubes with fins of rectangular, triangular, trapezoidal, and parabolic cross sections, and for a commercially-available finned tube. A stainless steel finned tube was also tested to investigate the effect of thermal conductivity. Maximum enhancements of about 4.8 were obtained under vacuum conditions, and about 6.9 at atmospheric pressure, compared to a smooth tube having an outside diameter equal to the root diameter of the finned tubes. The optimum fin spacing was found to be about 2.0 mm for rectangularly shaped-fins with a fin-thickness of 1.0 mm, and fin height of 0.5 and 1.5 mm. Fins with a parabolic shape were shown to perform better than fins of rectangular shape, and fins were shown to degrade the performance of stainless steel tubes. The effects of vapor shear were also shown to have only a small influence on the steam-side heat transfer coefficient. A theoretical model proposed by Webb et al. was found to underpredict the experimental data. Several suggestions to modify this model are described. Keywords: External fin; Heat transfer coefficient; Enhancement, Condenser tubes (Theses).

Download or read book Film Condensation of Steam on Externally Enhanced Horizontal Tubes written by Evagelos S. Mitrou and published by . This book was released on 1986 with total page 189 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heat-transfer measurements were made for filmwise condensation of steam on externally enhanced horizontal tubes under vacuum and at atmospheric pressure. Data were obtained for copper tubes with circular fins of rectangular, triangular, trapezoidal, and parabolic cross sections for spiral fins of triangular cross section, for commercially available finned tubes and for wire-wrapped tubes. Four spirally finned tubes from each of Cu, Cu-ni, A1 and stainless steel and two tubes with fins of rectangular cross section from each of Cu-Ni and A1 were manufactured and tested to investigate the effect of thermal conductivity. Among sprially finned tubes, the optimum fin pitch was found to be 1.6 mm. The tubes with a parabolic fin shape showed the best performance with steam-side enhancements of 4.1 and 6.2 under vacuum and at the atmospheric pressure respectively. Enhancement ratios as high as 3.5 and 2.1 were obtained under vacuum and at atmospheric pressure, respectively, for the commercially available finned tubes. The heat-transfer performance decreased with decreasing tube metal thermal conductivity. For the wire-wrapped tubes, an optimum pitch to wire diameter ratio of about 5.1 was found, with steam-side enhancements of about 1.9 and 2.2 under vacuum and at atmospheric pressure, respectively. A recent theoretical analysis of laminar film of low-surface-tension fluids on wire-wrapped tubes was modified to include the condensate retention of the tube due to the high surface tension of water. Agreement between this modified analysis and the experimental data was favorable. Keywords: Heat transfer coefficient.

Download or read book Film Condensation of Steam on Externally Finned Horizontal Tubes written by Frederick A. Flook and published by . This book was released on 1985 with total page 147 pages. Available in PDF, EPUB and Kindle. Book excerpt: Filmwise condensation measurements of steam were made on horizontal finned tubes under vacuum and near-atmospheric conditions. Data were obtained for copper tubes with fins of rectangular, triangular, trapezoidal, and parabolic cross sections, and for a commercially-available finned tube. A stainless steel finned tube was also tested to investigate the effect of thermal conductivity. Maximum enhancements of about 4.8 were obtained under vacuum conditions, and about 6.9 at atmospheric pressure, compared to a smooth tube having an outside diameter equal to the root diameter of the finned tubes. The optimum fin spacing was found to be about 2.0 mm for rectangularly shaped-fins with a fin-thickness of 1.0 mm, and fin height of 0.5 and 1.5 mm. Fins with a parabolic shape were shown to perform better than fins of rectangular shape, and fins were shown to degrade the performance of stainless steel tubes. The effects of vapor shear were also shown to have only a small influence on the steam-side heat transfer coefficient. A theoretical model proposed by Webb et al. was found to underpredict the experimental data. Several suggestions to modify this model are described. Keywords: External fin; Heat transfer coefficient; Enhancement, Condenser tubes (Theses).

Download or read book Heat Exchangers written by S. M. Sohel Murshed and published by BoD – Books on Demand. This book was released on 2017-04-26 with total page 219 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents contributions from renowned experts addressing research and development related to the two important areas of heat exchangers, which are advanced features and applications. This book is intended to be a useful source of information for researchers, postgraduate students, academics, and engineers working in the field of heat exchangers research and development.

Download or read book Condensation Heat Transfer Enhancement written by V. G. Rifert and published by WIT Press (UK). This book was released on 2004 with total page 402 pages. Available in PDF, EPUB and Kindle. Book excerpt: In processes with condensation of steam-to-gas compositions or refrigerative agents an intensification of condensation is often required because thermal resistance on the condensation side can be greater than the thermal resistance of the heat transfer wall on the cooling side. In this work, a pair of researchers from the National Technical U. of Ukraine and the State Academy of Refrigeration (Ukraine) provide information about the enhancement of condensation, including research results from the former USSR they feel deserves wider dissemination as well as discussion of different theoretical models of the condensation process. The US office of WIT Press is Computational Mechanics. Annotation : 2004 Book News, Inc., Portland, OR (booknews.com).

Download or read book Energy Research Abstracts written by and published by . This book was released on 1992 with total page 886 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Power Condenser Heat Transfer Technology written by P. J. Marto and published by Hemisphere Pub. This book was released on 1981 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental Study of Filmwise Condensation of Horizontal Surface with Structured Asymmetry written by Huy Truong and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Filmwise condensation occurs in many important applications related to power generation, refrigeration and thermal management of devices. The rate of filmwise condensation is inversely related to the thickness of the film. Gravitational and vapor shear forces play an important role in drainage of the condensate film in most horizontally and vertically oriented surfaces. In this thesis, a passive method of condensate drainage in the absence of gravitational and vapor shear forces is presented. Specifically, condensation of a highly wetting fluid on a horizontal surface with repeating asymmetric millimeter-sized ratchet-like (asymmetrically-profiled saw-tooth) structured surface, with periodically located film drainage pathways in the span-wise direction, is characterized. The overall hypothesis is that such geometry would result in a net steady-state preferential (partial towards the steep side of the ratchet) drainage of a film that condenses on the structured surface. The hypothesis is tested experimentally in two parts. In the first part, condensate growth within an asymmetric ratchet is characterized to determine whether the condensate grows preferentially towards the crest of one of the faces. Visualization experiments were performed on 30-60 degree ratchets to show that the condensate rises to the crest of the steeper wall before the shallow. In the second part, the goal is to determine whether such repeating asymmetry can lead to a net directional motion of the condensate. Span-wise pathways in the form of periodic walls are included on the surface to aid with drainage. The drainage pathway density is represented as non-dimensional drainage pathways per meter depth of the substrate. Both global and film visualization experiments are performed to characterize the differences in condensation between the symmetric and asymmetric surfaces. Experiments are performed using PF5060 on a brass surface with ratchets of 3 mm pitch, and 15-75 degree asymmetry. Results of the asymmetric ratchet are compared against a control test surface with 45 – 45 degree symmetric ratchets. The effect of variation of span-wise condensate drainage pathways, ranging from 121 to 363, is characterized. Experiments are performed at varied wall subcooling temperatures from 1-10°C. Global mass collection results indicate that all characterized asymmetric ratchet surfaces exhibit a net directional drainage of condensate while the symmetric control surfaces exhibit no preferential drainage. Among the asymmetric ratchets, the total mass flux rate increases with decrease in drainage pathway density while the net mass flux rate increases with pathway density. Visualization of the film provides qualitative reason for the observed global trends.Keywords: horizontal filmwise condensation, asymmetric, microstructures, passive directional drainage, phase change, ratchets, condensate drainage

Download or read book The Condensation of Ammonia water Mixtures in a Horizontal Shell and Tube Condenser written by Christopher Philpott and published by . This book was released on 2003 with total page 426 pages. Available in PDF, EPUB and Kindle. Book excerpt: