A generalized prediction model of waterside fouling for internally enhanced tubes in shell and tube condensers

Author(s):  
Rong Gao ◽  
Chao Shen ◽  
Xinlei Wang ◽  
Yang Yao
2003 ◽  
Author(s):  
Wei Li

This paper addresses fouling in a family of seven 15.54 mm I.D. copper, helically ribbed tubes, which have different ridge heights, helix angles, and number of ridge starts. A series of semi-theoretical linear fouling correlations as a function of the product of area indexes and efficiency indexes for long term combined precipitation and particulate fouling (PPF) in cooling tower systems and a series of semi-theoretical linear fouling correlations as a function of the efficiency indexes for particulate fouling were developed. The correlations can be directly used to assess the fouling potential of enhanced tubes in actual cooling water situations.


2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Wen-Tao Ji ◽  
Chuang-Yao Zhao ◽  
Jessica Lofton ◽  
Zeng-Yao Li ◽  
Ding-Cai Zhang ◽  
...  

In this work, the condensation of refrigerants on a single, high-density, low-fin tube and full-sized shell and tube condensers were investigated experimentally. The low-fin tube had an external fin density of 56 fins per inch (fpi) and fin height 1.023 mm. Another three-dimensional (3D) finned tube was also tested for comparison. The condensing heat transfer coefficient of the refrigerant R134a was first investigated outside a single horizontal tube at saturation temperature of 40 °C. The overall heat transfer coefficients of the two tubes were similar in magnitude. The condensing heat transfer coefficient of the low-fin tube was 16.3–25.2% higher than that of 3D enhanced tube. The experiments of the two condensers mounted with low-fin and 3D enhanced tubes were then conducted in centrifugal and screw chiller test rigs. It was found that chillers with the two different condensers generally had the same refrigeration capacity under the same experiment conditions. The refrigeration capacity of the screw chiller was smaller. It had fewer tube rows and elicited fewer inundation effects owing to the falling condensate. The heat transfer coefficients of the condensers with R134a in centrifugal chillers equipped with high-density low-finned tubes were higher than those in the screw chillers. The total number of tubes for low-fin tube condensers, in the two chillers, was reduced by approximately 15% compared with the use of domestic advanced condensers equipped with the 3D enhanced tubes.


1983 ◽  
Vol 105 (2) ◽  
pp. 358-365 ◽  
Author(s):  
W. J. Marner ◽  
A. E. Bergles ◽  
J. M. Chenoweth

As the efforts to produce more efficient heat transfer equipment continue, an increasing number of augmented surfaces are being produced commercially. Consequently, the designer faces an almost overwhelming task in comparing and evaluating the performance of various surfaces because of the many different ways in which the test data are currently presented in the literature. Thus, a uniform format for presenting pressure drop and heat transfer data for enhanced surfaces has become a necessity. This paper is concerned with one important aspect of this problem, namely, that of tubular enhanced surfaces used in shell-and-tube heat exchangers. As an initial step, the subject is limited to single-phase pressure drop and heat transfer; however, both tubeside and shellside flow are taken into consideration. A comprehensive list of commerical augmented tubes which may be considered for use in shell-and-tube exchangers is given, along with a survey of the performance data which are available in the literature. A standardized data format which uses the inside and outside envelope diameters as the basis for presenting the various geometrical, flow, and heat transfer parameters for all tubular enhanced surfaces is proposed and discussed.


Author(s):  
Zhixian Ma ◽  
Jili Zhang ◽  
Dexing Sun

Inundation effect, decrease of condensation heat transfer coefficient (CHTC) induced by both falling condensate from the neighboring tubes above and condensing condensate form the vapor, significantly affects the CHTC of tube bundles composed of smooth and enhanced tubes. This paper experimentally studied the inundation effect of smooth tube and three kinds of enhanced tubes (3D-A, 3D-B and 2D-A), put forward a scheme to eliminate the inundation effect caused by falling condensate and check it by experimental investigation. HFC134a and HFC245fa (substitutes of CFC12 and CFC11, respectively) were condensed in the experiment. Nominal diameter and active length of each test tube is 19.05mm and 500mm, respectively. Diversion ducts were fixed into the test tube bundle to eliminate tube row effect (part of the inundation effect caused by the falling condensate). Drainage strip was equipped on the test tubes to abate the inundation effect induced by condensed condensate. The (These) experimental results show: (1) Inundation effect of HFC 134a and HFC245fa on smooth tube bundle is not as severe as that predicted by Kern’s model. (2) 3D-B enhanced tube is dramatically affected by the inundation effect caused by falling condensate; (3) The equipped diversion ducts can eliminate tube row effect and improve the CHTC of tube bundles composed of smooth and 3D-B tubes. (4) The equipped drainage strip can further enhance the CHTC of 3D-A and 2D-A tubes in the tube bundle.


2006 ◽  
Vol 26 (11-12) ◽  
pp. 1334-1338 ◽  
Author(s):  
Z.H. Ayub ◽  
M.-C. Chyu ◽  
A.H. Ayub

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