Condensation heat-transfer measurements of refrigerants on externally enhanced tubes

  • 148 Pages
  • 2.21 MB
  • English
Naval Postgraduate School, Available from National Technical Information Service , Monterey, Calif, Springfield, Va
Mechanical engine
The Physical Object
Pagination148 p.
ID Numbers
Open LibraryOL25460418M

Since the end of s, condensation heat transfer inside horizontal tubes in heat exchangers for air conditioners is enhanced by finned tubes.

During condensation, microfin tubes show a heat transfer enhancement when compared with equivalent smooth tubes under the same operating conditions, that is partly due to the mereCited by: Refrigerant vaporization inside enhanced tubes: A heat transfer model measurements, and heat transfer coefficient data, obtained with infrared thermography, are presented and analyzed for two.

Preliminary information will be presented about heat transfer performance and pressure drop of herringbone tubes. Particular reference will also be given to available information on condensation of refrigerants in enhanced tubes when small amounts of compressor oil are present.

Description Condensation heat-transfer measurements of refrigerants on externally enhanced tubes FB2

Heat transfer inside horizontal smooth tubesCited by: In this study, condensation heat transfer coefficients (HTCs) of a plain tube, low fin tube, and Turbo-C tube were measured for the low pressure refrigerants CFC11 and HCFC and Condensation heat-transfer measurements of refrigerants on externally enhanced tubes book the medium pressure refrigerants CFC12 and HFCa.

All data were taken at the vapor temperature of 39°C with a wall subcooling of 3–8° by: For evaporation, the heat transfer coefficient ratio (compares the heat transfer coefficient of the enhanced tube to that of a smooth tube) of the 2EHT tubes is – (with an enhanced. In this study, external condensation heat transfer coefficients (HTCs) of six flammable refrigerants of propylene (R), propane (R), isobutane (Ra), butane (R), dimethylether (RE), and HFC32 were measured at the vapor temperature of 39°C on a fpm low fin and Turbo-C tubes.

All data were taken under the heat flux of and kW/m2 for the Iow fin and Cited by: 3. Evaporation and Condensation Heat Transfer Enhancement for Alternative Refrigerants Used in Air-Conditioning Machines () Experimental study on the heat transfer performance of a zeotropic refrigerant mixture in horizontal tubes, Proceedings of Evaporation and Condensation Heat Transfer Enhancement for Alternative Refrigerants Cited by: 3.

Katsuta, M, Sato, R & Niki, YCondensation and evaporation heat transfer performance by using HFOyf refrigerant in flat-tube: ∼The effect of projection on flat-tube inner wall and lubrication oil on heat transfer∼. in ACRA - Proceedings of the 7th Asian Conference on Refrigeration and Air Conditioning.

Society of Air-conditioning and Refrigerating Engineers of Korea, SAREK Author: Masafumi Katsuta, Ryo Sato, Yuhei Niki. correlations for condensation of new refrigerants inside smooth and enhanced tubes.

Kedzierski and Goncalves () proposed correlation for horizontal convective condensation of alternative refrigerants within a micro-fin tube. Thipjak et al., () modified the Cavallini et al.

() correlation for high mass flux of HFCa for. Theses refrigerants all have GWP measure of under Due to the differences on condensation heat transfer and pressure drop for refrigerants in various heat exchangers, investigation is also carried out for other types of heat exchangers like plate type, shell and tube type etc.

Based on the investigations, experimental correlations of Author: Byunghoon Shon, Yong Tae Kang, Yong Chan Kim. condensation heat transfer in microfm tubes with pure refrigerants.

With this correlation, the condensation heat transfer characteristics in some kinds of microfin tubes can be predicted very well. INTRODUCTION The microfm tube is widely used in heat pump and refrigeration systems for.

Forced Convection Condensation in Tubes: A Heat Transfer Correlation for Condenser Design. ASHRAE Transactions, 79, – [52] Wen, M.Y., & Ho, C.Y. Condensation Heat-Transfer and Pressure Drop Characteristics of Refrigerant R/Ra–Oil Mixtures in Serpentine Small-Diameter U.

Condensation Heat Transfer Coefficient CAVALLINI, CAVALLINI KOYAMA 0 50 0 1 Deviation (%) xref R32 R Ra.

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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 and a nonazeotropic refrigerant mixture (NARM) of 75% Ra and 25% R (by mass) to study their thermal performance in Cited by: 2.

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 by: Comparison among four refrigerants; RA provides better condensation heat transfer characteristics and it yields higher condensation heat transfer coefficients than those of other refrigerants by 8 to 27%.

However, the condensation heat transfer coefficients of RC are much lower than those of other refrigerants for all investigated by: 1. 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 measurements are provided. Experimental Measurements of Condensation Heat Transfer Coefficients for Refrigerant HFOyf Experimental tests were conducted on a parallel flow condenser with HFOyf as the working fluid on an AC system bench to determine average and local heat transfer coefficients during condensation of HFOyf for mass flow rates Author: Gursaran D.

Mathur. condensation heat transfer in tubes. When condensation occurs on horizontal and short vertical plates, condensate film motion is generally laminar.

On vertical tubes and long vertical plates, film motion can become turbulent. Grober et al. () suggested that a Reynolds number of could be used as the critical point at which.

Details Condensation heat-transfer measurements of refrigerants on externally enhanced tubes FB2

of HFCa was conducted in references [5–8]. It has been generally accepted that the condensation heat transfer of HFCa is better than that of CFC For example, the condensation heat transfer performance of Ra on a horizontal tube was conducted in [5] and three various enhanced tubes, a plain tube, low fin tube and Turbo-C tube,Cited by: CONDENSATION OF REFRIGERANTS 12 AND a IN HORIWNTAL TUBES WITH AND WITHOUT OILS David Kistler Hinde, M.S.

Department of Mechanical and Industrial Engineering University of lllinois at Urbana-Champaign, J. Chato, Advisor ABSTRACT This study investigated local condensation heat transfer and pressure drop for pure R.

Abstract. The present paper describes the results of experimental investigations of heat transfer during condensation of Ra, RA and RC in Cited by: 6. by Liu 4\ condensation and evaporation heat transfer and pressure drop of R!a and R!11 in a tube were investigated[ The condensation heat transfer for R!a are 7 to 07) higher and the pressure drop is 49) higher than those for R!11[Recently\ChamraandWebb 5 testedsomeadvanced micro!_nned tubes formed by applying a second set of.

Condensation heat transfer of low GWP refrigerant HFOyf was measured in a horizontal tube (inner diameter: 4 mm) at a mass flux range of - kg m -2 s -1. EHD ENHANCEMENT OF BOILING/CONDENSATION HEAT TRANSFER OF ALTERNATE REFRIGERANTS AND FROST CONTROL Final Report - Principal Investigator Michael M.

Ohadi, Ph.D., Professor Department of Mechanical Engineering University of Maryland, College Park, MD Tel:Fax: September Prepared for The : M. Ohadi. predictions of both the heat transfer and pressure drop correlations for condensing refrigerants in the Intermittent flow regime.

This was done utilizing a novel method involving the temporal and spectral analysis of the light intensity of the local flow regime, as seen through a sight glass. An experimental setup was designed, built and. refrigeration systems. This paper describes a study to compare the condensation heat transfer coefficients of the two fluids.

Analytical and experimental study of condensation heat transfer dates back to Nusselt's pioneering analysis [] of condensation on a vertical plate under the action of gravity with negligible vapor shear. Book digitized by Google from the library of New York Public Library and uploaded to the Internet Archive by user tpb.

Condensation heat-transfer measurements of refrigerants on externally enhanced tubes. by Zebrowski, David Stephen.

texts. eye [4],studied a new general flow pattern/flow structure based heat transfer model for condensation inside horizontal, plain tubes. The model predicts local condensation heat transfer coefficients for the following flow regimes: annular, intermittent, stratified-wavy, fully stratified and mist flow.

The augmentation of dropwise condensation is pointless, because the heat transfer coefficients are already so high. It has been found that average coefficients for film condensation of steam on horizontal tubes can be improved up to 20 percent by strategically placing strips of teflon or other nonwetting material around the tube circumference.

cause of their very high heat transfer density. Thus the flow and heat transfer characteristics in small and capil-lary tubes have been extensively investigated for various fluids such as air, water and some refrigerants [1]. But the heat transfer characteristics associated with the evaporation and condensation of the HFCs refrigerants.ABSTRACT: In this study, condensation heat transfer tests were conducted in flat aluminum multi-channel tubes using RA, and the results are compared with those of R Two internal geometries were tested; one with a smooth inner surface and the other with micro-fins.Refrigerantcharge,pressuredrop,andcondensationheat transferinflattenedtubes gated using two refrigerants, Ra and RA, under condensation conditions at 35 C.

The tubes Fig. 8 is a plot of the condensation heat transfer.