A simple prediction method for condensation heat transfer inside a micro-fin tube



Publisher: U.S. Dept. of Commerce, Technology Administration, National Institute of Standards and Technology in Gaithersburg, MD

Written in English
Published: Pages: 37 Downloads: 389
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Subjects:

  • Heat -- Transmission -- Measurement,
  • Condensation -- Measurement

Edition Notes

StatementF. Marchesi Donati, M.A. Kedzierski
SeriesNISTIR -- 6417
ContributionsKedzierski, Mark A, National Institute of Standards and Technology (U.S.)
The Physical Object
FormatMicroform
Pagination37 p.
Number of Pages37
ID Numbers
Open LibraryOL13626437M
OCLC/WorldCa43478170

1 day ago  Use the Heat Transfer Module, an add-on to the COMSOL We share an example of a heat exchanger in this video to outline the modeling steps for creating a realistic simulation of nonisothermal flow. CC-THERM shell and tube heat exchanger applications include vertical and horizontal condensation, evaporation and column thermo siphons. An experimental study was carried out to explore the heat transfer characteristics on the outside of smooth and enhanced tubes, during evaporation and condensation of RA in the annulus of a tube-in-tube heat exchanger. The three-dimensional enhanced surface tube consisted of primary enhancement patterns and secondary patterns; results were compared to the performance of an . How to find the dew point in buildings, when does moisture condense on surfaces and in cavities. In addition to providing a psychometric chart this article includes dew point calculation formulas and references to dew point and psychometric chart calculations, research, and psychometric chart preparation or interpretation. The dew point defines when moisture will begin to condense on building. An alternative model for calculating condensation heat transfer following a main stream line break (MSLB) accident is proposed. The proposed model predictions and the current regulatory model predictions are compared to the results of the Carolinas Virginia Tube Reactor (CVTR) test. The very.

correlations for the condensation heat transfer and/or frictional pressure drop of refrigerant in micro-fin tube. However, there are still unsolved problems as, (1) The void fraction in micro-fin tube was estimated using the void fraction correlation proposed for smooth tube in many cases. decreases with increasing condensing temperature. The average heat transfer coefficient is % higher for micro-fin tube than that of smooth tube, with moderate increase in pressure drop ranging from %. New correlations based on the data gathered during the experimentation for predicting condensation heat transfer.   HEAT TRANSFER DESIGN METHODS Design Method 1 Design Method 2 PREFERRED ROUGHNESS TYPE AND SIZE FORCED CONDENSATION INSIDE TUBES Internally Finned Tubes Twisted-tape Inserts. Roughness In-tube Condensation Falling Film Evaporation Correlations. This paper presents Local convective condensation Measurements for four refrigerants: R, RA (R32/R, 50/50 % mass), R, and R32 in a micro-fin tube. Both heat transfer and pressure drop measurements are provided.

flat tube, and fourfold for the micro-fin flat tube. Kim et al. () obtained the R evaporation heat transfer coefficient in an oval tube (1: ), which was made by deforming the mm O. D. micro-fin tube. The heat transfer coefficient of the oval tube was 2% to 15% higher than that of the round tube. The pressure drops were. In the present study the local condensation heat transfer characteristics in a horizontal microfin tube are found to be about 2 times higher than those of a smooth tube with the same inner diameter. This enhancement effect on heat transfer coefficient seems mainly caused by the enlargement ratio of heat transfer .   Sapali SN, Patil PA () Heat transfer during condensation of HFCa and RA inside of a horizontal smooth and micro-fin tube. Exp Therm Fluid Sci – CrossRef Google Scholar Schlager LM, Pate MB, Bergles AE () Evaporation and condensation heat transfer and pressure drop in horizontal mm microfin tubes with. Fig.1 Predicted Evaporating Heat Transfer Coefficient Ratio A correlation developed by M. Shah (International Journal of Heat and Mass Transfer, Vol. 22, ) for heat transfer coefficients for film-type condensation inside horizontal tube~ ~as used to predict.

A simple prediction method for condensation heat transfer inside a micro-fin tube Download PDF EPUB FB2

Abstract This study examines an alternative method for modeling in-tube condensation heat transfer. The method's fundamental premise is that the heat flux is directly proportional to the difference between the enthalpy of the vapor at saturated free stream conditions and the enthalpy of the condensed subcooled liquid at the : F M.

Donati, Mark A. Kedzierski. Get this from a library. A simple prediction method for condensation heat transfer inside a micro-fin tube.

[F Marchesi Donati; Mark A Kedzierski; National Institute of Standards and Technology (U.S.)]. An improved predictive model called the “equivalent Reynolds number model” is introduced Use of the new model requires prediction of the single-phase heat transfer coefficient and the two-phase pressure gradient.

For condensation in micro-fin tubes, both vapor shear and surface tension forces contribute to the condensing by: This paper reports on the influence of the spiral angle on the heat transfer during condensation inside spiralled micro-fin tubes having all other geometric parameters constant.

Tests were conducted for condensation of R, Ra, and RC inside a smooth ( mm outer diameter) and three micro-fin tubes with approximately the same Cited by:   An experimental investigation was conducted into the heat transfer characteristics during in-tube condensation of horizontal smooth, micro-fin, and herringbone tubes.

The study focused on the heat transfer coefficients of refrigerants R, Ra, and RC inside a series of typical horizontal smooth, micro-fin, and herringbone tubes at a Cited by:   the final expression to compute the heat transfer coefficient for pure-refrigerant during condensation inside micro-fin tubes can be expressed as (36) h = ρ l c pl τ w ρ l T + Rx where the heat transfer coefficient is in W m −2 K −1.

Flow boiling heat transfer coefficients of R22, Ra, R, RA and RA inside a smooth horizontal tube (6mm I.D., 6m length) were measured at a refrigerant mass flux of about kg/m2s.

This study presents experimental data of CO2 flow condensation heat transfer for mass fluxes ranging from to kg/m²-s inside a mm inside diameter, smooth horizontal copper tube, at. Shah, M.M.

A general correlation for heat transfer during film condensation inside pipes. Int. Heat Mass Transf. 22, – [Google Scholar] Shah, M.M.

A new correlation for heat transfer during condensation in horizontal mini/micro channels. Int. Refrig. 64, – [Google Scholar]. The actual inner surface heat transfer area of the microfin tube relative to that of a smooth one with the same diameter to the root of the fins, is for 5-mm-OD tube type and for mm-OD tube type, respectively, indicating a higher promotion for the condensation heat transfer.

Abstract. In this paper, the effects of fin height and fin angle on condensation heat transfer inside microfin tubes were investigated. One smooth and six microfin tubes with outer diameters of mm were used to condense Ra at 30 °C and a mass flux range – kg/m 2 s.

Each of the microfin tubes tested had 60 fins and a spiral angle of 18°. 1. Introduction. In design practice, accurate predictions of the heat transfer and pressure drop are of great importance. The pressure drop in condenser affects not only pumping power consumption but also significantly the heat transfer performance due to the dependence between the local condensing temperature and pressure of refrigerant, especially in the case of condensation in micro-fin.

Issam Mudawar, in Advances in Heat Transfer, Flow Orientation Effects on Flow Condensation at 1 g e. Condensation pressure drop and heat transfer characteristics are highly flow regime dependent.

While the topic of condensation flow regime determination is widely available in the literature, the vast majority of published works have been focused on horizontal flow [–].

Wilson et al. [9] measured heat transfer during condensation of Ra and RA in a horizontal tube of mm and channels obtained by flattening it.

They concluded that flattened tubes have higher. For the experimental data of CO 2 condensation heat transfer in the micro-fin tubes, the overall prediction accuracy by the Cavallini et al. () correlation is acceptable with a mean absolute. A.S. Dalkilic, S.

WongwisesExperimental study on the condensation heat transfer coefficients in high mass flux region in annular flow regime of HFCa inside the vertical smooth tube Heat Transfer Eng., 32 (), pp. where ρ L and ρ G, are the liquid and gas densities, λ L the liquid thermal conductivity, z the distance from the start of condensation, η L the absolute liquid viscosity and ΔT the difference between the saturation temperature and the wall temperature, and where h LG is the latent heat of evaporation and c L the specific heat of the liquid.

The local heat transfer in a closed tube is. Condensation Heat Transfer of Refrigerants HCFCa, HCFC and HCFC22 in a Horizontal Smooth Tube and a Horizontal Micro-Fin Tube 30th National Symposium, Yokohama, pp.

A method is presented for estimating the condensation heat transfer coefficient in a horizontal, spirally grooved microfin tube. Based on the flow observation study performed by the authors, a laminar film condensation model in the annular flow regime is proposed. In the annular regime, the heat transfer coefficients h of the two kinds of in-tube 3-D micro-fin tubes decreases as the vapor quality x decreases.

The regressed condensation heat transfer correlation from the experimental data of the annular flow region is obtained. The dispersibility of the experimental data is inside the limits of ±25%.

In-Tube Heat Transfer and Pressure Drop of Ra and Ester Lubricant Mixtures in a Smooth Tube and a Micro-Fin Tube: Part I-Evaporation, ASHRAE Trans. (2), – Google Scholar 5. This paper presents local convective-condensation measurements for four refrigerants: Ra, RA (R32/R, 50/50% mass), R, and R32 in a micro-fin tube.

Both heat transfer and pressure drop. The predictions of condensation pressure drops of R12, R22, R32, R, RA, Ra, R22, R and Ra flowing inside various horizontal smooth and micro-fin tubes are made using the numerical. The above heat transfer prediction method cannot be the condensation process inside a tube departs from this equilibrium when the liquid condensate .P.

Flow Pattern Identification with Power Spectral Density Distributions of Pressure Traces during Refrigerant Condensation in Smooth and Micro-Fin Tubes, J. Heat. Degradation of condensation HTC (Heat Transfer Coefficient) under an air presence in a vertical tube was explored both experimentally and analytically, with the aim of developing evaluation methods for the design of passive containment cooling systems in the next generation reactors.

Measurements were done using a stainless steel tube of @article{osti_, title = {A prediction method for heat transfer during film condensation on horizontal low integral-fin tubes}, author = {Honda, H and Nozu, S}, abstractNote = {A method for predicting the average heat transfer coefficient is presented for film condensation on horizontal low integral-fin tubes.

Approximate equations based on the numerical analysis of surface tension. Measurement of Condensation Heat Transfer Coefficients at Near-Critical Pressures in Refrigerant Blends J.

Heat Transfer (August,) Heat Transfer Performance During Condensation Inside Spiralled Micro-Fin Tubes. Our problem we are considering is heat-transfer to fluid inside of a heated tube – forced-convection heat transfer plus radial conduction T 1 Heat-transfer coefficient on the inside of a heated tube T o >T 1 method to free convection heat transfer.

as a resistance to heat transfer. Dropwise condensation • The condensed vapor forms droplets on the surface. • The droplets slide down when they reach a certain size. • No liquid film to resist heat transfer. • As a result, heat transfer rates that are more than 10 times larger than with film condensation.

This paper critically reviews the existing theoretical models of heat transfer prediction in condensing inside plain tubes. More than 20 theoretical methods and correlations for heat transfer prediction during different modes of condensate film flow and phase distribution are considered.

Lack of prior substantiation of correct application of different turbulent viscosity models for heat. Similar picture holds for inside tube condensation, where annular flow structure predominates. In such case the heat transfer coefficient is primarily dependent on the convective mechanism.

In the paper a method developed earlier by D. Mikielewicz et al. () is applied to calculations of heat transfer coefficient for inside tube condensation.The research showed that the condensation heat transfer coefficient of both tubes increased with the increasing mass velocity of refrigerant.

when the mass velocity of refrigerant increased from kg/m 2 s to kg/m 2 s, the condensation heat transfer coefficient in tube A was % to % higher than that of tube B. However, the flow.Heat Transfer During Condensation of HFCa and RA Inside of a Horizontal Smooth and Micro-Fin Tube.

Experimental Thermal and Fluid Science, 34 (8), – [43] Shah, M.M. ().