Some aspects of film condensation of steam on finned tubes

by James M. Coumes

Publisher: Naval Postgraduate School, Publisher: Available from the National Technical Information Service in Monterey, Calif, Springfield, Va

Written in English
Published: Pages: 148 Downloads: 612
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Edition Notes

ContributionsMarto, P. J.
The Physical Object
Pagination148 p.
Number of Pages148
ID Numbers
Open LibraryOL25451403M

@article{osti_, title = {A test of some condensation models in the presence of a noncondensable gas against the ecotra experiment}, author = {Vernier, P J and Solignac, P}, abstractNote = {The authors work was restricted to elementary models of condensation, coupling a laminar water film with an air-stream mixture boundary layer, under steady-state conditions, for some . Under such conditions, an insulating superheated steam film develops. Once the tube metal temperature has reached °F in boiler tubes or °F in superheater tubes (assuming low alloy steel construction), the rate of oxidation increases dramatically; this oxidation occurs repeatedly and consumes the base metal.   In evaporative surface condensers, the steam enters at the top of the condenser in a series of pipes over which a film of cold water is falling. At the same time, current of air is made to circulate over the film of water. As the air circulates over the water film, it evaporates some . (Problem in the Book) A horizontal tube of mm outer diameter, with a surface temperature of 34oC, is exposed to steam at bar. Estimate the condensation rate and heat transfer rate per unit length of the tube. Schematic: Assumptions: (1) Laminar film condensation, (2) Negligible non-condensibles in steam.

A growing interest in high-finned tube dehumidifiers has prompted HTRI to develop a new method for Xace ™.This new method designs a dehumidifier that condenses a small amount of water from a saturated or partially saturated air stream as the stream is cooled by flowing over a bundle of high-finned tubes. tubes and as it heats, steam begins to form. The ascending force of this steam produced during the boiling causes liquid and vapors to flow upwards in parallel flow. At the same time the production of vapor increases and the product is pressed as a thin film on the walls of the tubes, and the liquid rises upwards. Fig Rising Film Evaporator. The heat released when condensing steam can be expressed as. Q = h e M s (1). where. Q = quantity of heat released (kJ, Btu) M s = mass of condensing steam (kg, lb). h e = specific evaporation enthalpy of steam (kJ/kg, Btu/lb). The heat transfer rate - or power - in a condensing steam flow can be expressed as. q = h e m s (2). @article{osti_, title = {Fin-efficiency calculation for condensation in the presence of noncondensable gases}, author = {Panchal, C B}, abstractNote = {Plate-fin heat exchangers are being considered for many condenser applications. They are commonly used for the gas-separation process because they can provide a high thermal performance to obtain a low mean-temperature difference.

Film Condensation Phase diagram of water. Source: CC BY-SA. Similarly as in the previous chapter, in this chapter we will discuss heat transfer with phase change, but in this case we will discuss condensation of gas phase (vapor-to-liquid phase change).. In general, condensation is the change of the physical state of matter from gas phase into liquid phase, and is the reverse of. Fig. 8. Variation of heat transfer coefficients from top of tube for steam-only runs. Fig. 9. Variation of condensate heat transfer coefficients from top of tube for steam-only runs. relatively small increments and the temperature profile in each stream is essentially linear. The latter assumption was used to obtain a relationship between gas. Fundamentals of Heat and Mass Transfer book. Read reviews from world’s largest community for readers. type questions for self-evaluation and better understanding of the subjectProblems related to the practical aspects of the subject have been worked outChecking the authenticity of dimensional homogeneity Be the first to ask a question /5(4). Classical aspects discussed include shell-and-tube heat exchangers, double pipe exchangers, reboilers, and condensers. New topics covered include process integration, heat exchanger selection, heat transfer associated with thermodynamic cycles, and ohmic heating. The book includes both worked examples and problems at the end of each chapter.

Some aspects of film condensation of steam on finned tubes by James M. Coumes Download PDF EPUB FB2

The film condensation heat transfer performance of six externally finned copper tubes has been evaluated. All tubes had rectangular-shaped fins with a height and thickness of 1 mm. The spacing between fins was,and mm.

Data were also obtained for a smooth tube whose outside diameter of mm was equal to the Cited by:   All finned tubes had inner and outer diameters of mm and mm respectively, and had a fin thickness of l.0mm and a fin spacing of mm.

The overall heat transfer coefficient (U sub o) was determined experimentally and the outside heat transfer coefficient (ho) was obtained utilizing a modified Wilson Plot procedure. The performance of two types of finned tubes viz. circular integral-fin tubes (CIFTs) and spine integral-fin tubes (SIFTs) was studied for the condensation of water and Ra.

Film condensation of steam on externally finned horizontal tubes. Item Preview remove-circle Film condensation of steam on externally finned horizontal tubes. by Flook, Frederick A.

some content may be lost due to the binding of the book. Addeddate Call number ocn CameraPages: 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 : Frederick A.

Flook. The previous theoretical model of film condensation on a single horizontal low finned tube is extended to include the effect of condensate inundation. Based on the flow characteristics of condensate on a vertical column of horizontal low finned tubes, two major flow modes, the column mode and the sheet mode, are considered.

When compared to a plain tube of fin-tip diameter and at the same vapor side temperature difference, heat-transfer enhancement ratios between and were found for the finned tubes compared to a plain tube in quiescent vapor conditions, while values between and were found when compared to a plain tube at the same vapor velocity.

Some aspects of film condensation of steam on finned tubes. distribution is unlimitedHeat-transfer measurements were made for filmwise condensation of steam on smooth tubes and finned tubes with rectangular-shaped fins.

The influence of fin root diameter on a single horizontal finned tube was examined by taking data for two families of. Morrison, Andrew T., and You, S. "Condensation of Steam on Finned Surfaces With Addition of a Surfactant." Proceedings of the ASME Summer Heat Transfer Conference collocated with the ASME Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems.

New experimental data are reported for the condensation of steam on square wire wrapped on horizontal instrumented copper tube. mm square cross-section wires made of.

Abstract. The fundamentals of condensation heat transfer for a pure vapor are reviewed. Calculational methods for the heat transfer coefficient and the pressure drop are presented for a wide variety of surface geometries and flow configurations, including shell-side condensation, in-tube condensation and direct-contact condensation.

Steam blowdown using the large vents of a PSP system is a long transient with many phases during which the condensation mode varies greatly over time depending on the NC content in the steam, the steam mass flow rate, and the subcooling of the pool.

The models presented here have been proven to work accurately for only some condensation modes. A theoretical model of film condensation on a horizontal finned tube developed in a previous work is generalized.

The new model includes the effects of condensate flow and heat transfer on the fin. A steam condenser is a closed vessel in which steam is condensed by abstracting the heat by cooling it with water and where the pressure is maintained below atmospheric pressure.

The condensed steam is known as condensate. The efficiency of the steam power plant is increased by the use of a condenser. The steam condenser is an essential. Condensation of Steam Bubbles in a Subcooled Pool.

Applied to an engineering oval finned tube, condensation HTC, film thickness, wall shear in the two condensation. In incomplete. Film condensation occurs when the temperature of a vertical, impermeable, and wettable wall next to a porous medium saturated with vapor falls below saturation temperature (Fig.

).In addition to gravity-driven downward liquid flow, the liquid also infiltrates the vapor region due to capillary force. The latter will create a two-phase region between the liquid film and the vapor region.

At pure steam case, the longitudinal finned tube played a positive effect on the condensation heat transfer, showing a growth of the condensation heat transfer coefficient by a factor of – At the steam–air case, the longitudinal finned tube generated restrictions on the condensation heat transfer process when air mass fraction was.

From Figure it can be seen that for equal duties and flows the temperature difference for counter-current flow is lower at the steam inlet than at the outlet, with most of the steam condensation taking place in the lower half of the plate.

The reverse holds true for co-current flow. In this case, most of the steam condenses in the top half of the plate, the mean vapour velocity is lower. The Newton law of cooling give us the heat flux from the bulk steam inside the containment at temperature T b, to the coolant moving inside the finned tube at temperature T c: (1) q ″ = h T (T b − T c) with h T = 1 A 0 1 R c + R w + R foul + R lg where h T is the overall heat transfer coefficient which is defined with respect to the outer plane surface area, and the combination of.

A General Correlation for Heat Transfer during Film Condensation inside Pipes, Int. Heat Mass Transfer, 22, – Sklover, G. Generalized Data of Steam Condensation Computation in Horizontal Tube Bundles, Proc. 2nd International Symposium on Condensers and Condensation, Uni-versity of Bath, Bath, Somersetshire, England, pp.

The film condensation heat transfer performance of six externally finned copper tubes has been evaluated. All tubes had rectangular-shaped fins with a height and thickness of 1 mm. Many types of finned tubes, but also the emergence of new varieties, research in this area is greater [ ].

Process according to several aspects of general, fin shape, material, and other uses of finned tubes classification. In the condenser, finned tubes commonly used are the following form.

The heat transfer enhancement was studied during condensation of steam on a chilled vertical surface of a tube packed into a granulated material with different contact angles of wetting.

The. Kumar et al. reported experimental data for the condensation of steam on a plain tube with an outside diameter of 22 mm and an integral‐fin tube (with an outside diameter of 25 mm, fin height of mm, fin thickness of mm and fin spacing of mm).

A three‐dimensional pin‐fin tube was also tested with similar radial and longitudinal. New experimental data are reported for forced-convection condensation of ethylene glycol on a set of nine single, copper, integral-fin tubes.

The first set of five tubes had fin height and thickness of and mm ⁠, respectively, with fin spacings of, and mm ⁠.The second set of four tubes had fin spacing and thickness of and mm ⁠, respectively, and.

Katz and J. Geist, “Condensation on six finned tubes in a vertical row,” Trans. ASME,70, No. 8, – (). Google Scholar. An experimental investigation on the effects of air on filmwise condensation of PF dielectric fluid on plain and finned tube bundles.

International Journal of Heat and Mass Transfer, The tubes tested had an inner diameter of mm, a root diameter of mm, and fin heights ranging from mm to mm, in mm increments.

The outside heat transfer coefficient was determined first by finding the overall heat transfer coefficient, Uo, then by using the Modified Wilson Plot Technique. Calhoun: The NPS Institutional Archive Theses and Dissertations Thesis Collection Filmwise condensation of steam on externally-finned horizontal tubes.

Film condensation of steam on externally enhanced horizontal tubes Mitrou, Evagelos S. Monterey, California: U.S. Naval Postgraduate School (VacuumRuns,Tube38) 90 ComparisonofFinned-TubeDatawithDataof Flook[6](AtmosphericRuns,Tube38) 91 VariationofHeat-TransferCoefficientwith.

The main objective of this chapter is to study the liquid film condensation in a thermal desalination process, which is based on the phase change phenomenon. The external tube wall is subjected to a constant temperature.

The set of the non-linear and coupled equations expressing the conservation of mass, momentum and energy in the liquid and gas mixtures is solved numerically.Augmentation of horizontal in-tube condensation of steam John Henri Royal Iowa State University Follow this and additional works at: page(s) or section, they are spliced into the film along with adjacent pages.

Th;s may have necessitated cutting thru an image and duplicating adjacent THE FINNED TUBES With ξ 0 =Eq. (3) gives values of α i much higher than the heat transfer coefficient for the condensate in film condensation, except in the case of liquid metals.

For example, for steam at 30°C, α i ≈ MW/m 2 K, which may be compared with typical values of the heat transfer coefficient in the range 10–50 kW/m 2 K for the condensate film during film condensation.