Experimental Studies of Shell and Tube Condenser Fouling and Accelerated Particulate Fouling in Internal Helical-Rib Roughness Tubes

2003 ◽  
Author(s):  
Wei Li
Keyword(s):  
Cooling Tower ◽  
Experimental Studies ◽  
Cooling Water ◽  
Particulate Fouling ◽  
Enhanced Tubes ◽  
Shell And Tube ◽  
Condenser Fouling ◽  
Tube Condenser

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.

Semi-Theoretical Modeling Oscillatory Fouling in Enhanced Tubes in Cooling Tower Systems

2007 ◽  
Author(s):  
Wei Li
Keyword(s):  
Cooling Tower ◽  
Oscillatory Behavior ◽  
Linear Range ◽  
Specific Interest ◽  
Particulate Fouling ◽  
Internal Parameters ◽  
Enhanced Tubes ◽  
Adequate Accuracy ◽  
Oscillatory Model

The fluctuation of fouling data, a well-known fouling phenomenon, was recognized in applications three decades ago, but it had not yet been well understood. Of specific interest is long term, combined precipitation and particulate fouling in cooling tower systems. Fouling data collected in seven 15.54 mm I.D. copper, helically ribbed tubes at water velocity (1.07 m/s) at practical conditions shows an oscillatory behavior. In order to observe it, a water temperature difference of 3.0°C, or greater, was needed for adequate accuracy based on an uncertainty analysis. Oscillatory model was used to analyze the data. The frequencies of the fluctuation are the same for the seven tested tube geometries. A series of semi-theoretical correlations of fluctuation of the long-term cooling tower water fouling data were developed. It was found that there are two ranges of amplitudes of the fluctuation based on internal parameters: linear range and non-linear range.

scholarly journals Design improvement and experimental study on shell and tube condenser for bio-oil recovery from fast pyrolysis of wheat straw biomass

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
B. L. Salvi ◽  
T. Soni ◽  
S. Jindal ◽  
N. L. Panwar
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Water Flow Rate ◽  
Cooling Water ◽  
Gas Flow Rate ◽  
Design Improvement ◽  
Cooling Water Flow Rate ◽  
Bio Oil ◽  
Shell And Tube ◽  
Tube Condenser

AbstractIn this study, the design improvement was done in a shell and tube condenser for improved heat transfer and condensation of bio-oil vapour. The developed condenser has split shell and segmental baffles, which divide the shell in various zones and condensate collection points. The fast pyrolysis of wheat straw was done and the bio-oil vapour condensate collected from various outlets located at bottom of condenser shell. From experimental results it was found that production of bio-oil increased from 10.2 to 20.8% with increase in cooling water flow rate from 1000 to 2500 L/h; but, further increasing it beyond 2500 L/h provide marginal effects on production of bio-oil. The production of bio-oil increased from 15.2 to 20.7% as sweep gas flow rate was increased from 20 to 40 L/min at 2500 L/h of cooling water flow rate. But, further increase in sweep gas flow rate beyond 40 L/min resulted in to decrease in production of bio-oil. The novelty of this work is development of improved condenser with segmental baffles, which help in fractional condensation of bio-oil vapour, split shell for cleaning of outer surface of the cooling water tubes and compact design of condenser for optimal condensation of bio-oil.

The Performances of Internal Helical-Rib Roughness Tubes Under Fouling Conditions: Practical Cooling Tower Water Fouling and Accelerated Particulate Fouling

2003 ◽  
Vol 125 (4) ◽  
pp. 746-748 ◽  
Author(s):  
Wei Li
Keyword(s):  
Cooling Tower ◽  
Particulate Fouling

This paper addresses fouling in a family of seven copper helically ribbed tubes. Series of semi-theoretical linear fouling correlations for long term combined precipitation and particulate fouling (PPF) in cooling tower systems and for accelerated particulate fouling were developed.

Inundation Effect and Its Elimination in Shell and Tube Condenser

2010 ◽  
Author(s):  
Zhixian Ma ◽  
Jili Zhang ◽  
Dexing Sun
Keyword(s):  
Tube Bundle ◽  
Test Tube ◽  
Smooth Tube ◽  
Active Length ◽  
Hfc 134A ◽  
Enhanced Tubes ◽  
Tube Bundles ◽  
Enhanced Tube ◽  
Shell And Tube ◽  
Tube Condenser

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.

Mitigation of Particulate Fouling by Ozonation

2003 ◽  
Vol 125 (1) ◽  
pp. 147-150 ◽  
Author(s):  
Bang-Yenn Wu ◽  
S. H. Chan
Keyword(s):  
Heat Transfer ◽  
Calcium Carbonate ◽  
Cooling Tower ◽  
Cooling Water ◽  
Reynolds Numbers ◽  
Fouling Resistance ◽  
Low Reynolds Numbers ◽  
Particulate Fouling ◽  
High Reynolds ◽  
Deposit Layer

Heat transfer surface fouling introduces a major uncertainty into the design and operation of cooling water systems. Fouling caused by calcium carbonate CaCO3 typically occurs on heat transfer surfaces. Ozone has been successfully used for more than 90 years as a disinfectant in drinking water. Recently, it has been proposed to use ozone for cooling tower water treatment. In this research, the effectiveness of mitigation of calcium carbonate particulate fouling by ozone was studied systematically. The experimental results show that, at low Reynolds numbers, though the ozonation retards the initial calcium carbonate particulate fouling rate, the retardation led to a non-porous deposit layer and a higher asymptotic fouling resistance. However, at high Reynolds numbers, ozonation was found to reduce the asymptotic fouling resistance.

Simulation model of a screw liquid chiller for process industries using local heat transfer integration approach

2005 ◽  
Vol 219 (2) ◽  
pp. 95-107 ◽  
Author(s):  
C. V. Le ◽  
P. K. Bansal ◽  
J. D. Tedford
Keyword(s):  
Heat Transfer ◽  
Simulation Model ◽  
Cooling Water ◽  
Local Heat Transfer ◽  
Load Ratio ◽  
Local Heat ◽  
Process Industries ◽  
Integration Approach ◽  
Shell And Tube ◽  
Tube Condenser

This paper presents a system simulation model of an oil-injected screw liquid chiller, where the refrigerant shell and tube heat exchangers are modelled following local heat transfer integration approach. All major components of the system are modelled in a modular format such as an oil-injected screw compressor, a shell and tube condenser, a flooded evaporator, and a high side-float valve. The simulation results are validated with the experimental data of a multiple-chiller plant at a process industry. The validated results show that the part-load ratio and the glycol-water temperature at the evaporator inlet affect the system performance considerably as compared to the temperature of cooling water entering the condenser.

scholarly journals CONDENSATION OF WATER VAPOR IN A VERTICAL TUBE CONDENSER

2015 ◽  
Vol 55 (5) ◽  
pp. 306 ◽  
Author(s):  
Jan Havlík ◽  
Tomáš Dlouhý
Keyword(s):  
Heat Transfer ◽  
Water Vapor ◽  
Stream Flow ◽  
Flow Analysis ◽  
Cooling Water ◽  
Vertical Tube ◽  
Operating Conditions ◽  
Shell And Tube ◽  
Tube Condenser ◽  
Condensation Heat Transfer Coefficient

<p>This paper presents an analysis of heat transfer in the process of condensation of water vapor in a vertical shell-and-tube condenser. We analyze the use of the Nusselt model for calculating the condensation heat transfer coefficient (HTC) inside a vertical tube and the Kern, Bell-Delaware and Stream-flow analysis methods for calculating the shell-side HTC from tubes to cooling water. These methods are experimentally verified for a specific condenser of waste process vapor containing air. The operating conditions of the condenser may be different from the assumptions adopted in the basic Nusselt theory. Modifications to the Nusselt condensation model are theoretically analyzed.</p>

Masonry: the brittle or plastic material?

2019 ◽  
pp. 22-28
Keyword(s):  
Plastic Material ◽  
Experimental Studies ◽  
Point Of View ◽  
Plastic Properties ◽  
Plastic Deformations ◽  
Base Materials ◽  
Stress States ◽  
Creep Deformations ◽  
Structural Point

The results of experimental studies of masonry on the action of dynamic and static (short-term and long-term) loads are presented. The possibility of plastic deformations in the masonry is analyzed for different types of force effects. The falsity of the proposed approach to the estimation of the coefficient of plasticity of masonry, taking into account the ratio of elastic and total deformations of the masonry is noted. The study of the works of Soviet scientists revealed that the masonry under the action of seismic loads refers to brittle materials in the complete absence of plastic properties in it in the process of instantaneous application of forces. For the cases of uniaxial and plane stress states of the masonry, data on the coefficient of plasticity obtained from the experiment are presented. On the basis of experimental studies the influence of the strength of the so-called base materials (brick, mortar) on the bearing capacity of the masonry, regardless of the nature of the application of forces and the type of its stress state, is noted. The analysis of works of prof. S. V. Polyakov makes it possible to draw a conclusion that at the long application of the load, characteristic for the masonry are not plastic deformations, but creep deformations. It is shown that the proposals of some authors on the need to reduce the level of adhesion of the mortar to the brick for the masonry erected in earthquake-prone regions in order to improve its plastic properties are erroneous both from the structural point of view and from the point of view of ensuring the seismic resistance of structures. It is noted that the proposal to assess the plasticity of the masonry of ceramic brick walls and large-format ceramic stone with a voidness of more than 20% is incorrect, and does not meet the work of the masonry of hollow material. On the basis of the analysis of a large number of research works it is concluded about the fragile work of masonry.

Improvement Of Curvilinear Diagrams Of Concrete Deformation

2019 ◽  
pp. 99-104
Keyword(s):  
Reinforced Concrete ◽  
Peak Load ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Deformation Model ◽  
Reinforced Concrete Structures ◽  
Significant Difference ◽  
Deformation Diagrams

Problems when calculating reinforced concrete structures based on the concrete deformation under compression diagram, which is presented both in Russian and foreign regulatory documents on the design of concrete and reinforced concrete structures are considered. The correctness of their compliance for all classes of concrete remains very approximate, especially a significant difference occurs when using Euronorm due to the different shape and sizes of the samples. At present, there are no methodical recommendations for determining the ultimate relative deformations of concrete under axial compression and the construction of curvilinear deformation diagrams, which leads to limited experimental data and, as a result, does not make it possible to enter more detailed ultimate strain values into domestic standards. The results of experimental studies to determine the ultimate relative deformations of concrete under compression for different classes of concrete, which allowed to make analytical dependences for the evaluation of the ultimate relative deformations and description of curvilinear deformation diagrams, are presented. The article discusses various options for using the deformation model to assess the stress-strain state of the structure, it is concluded that it is necessary to use not only the finite values of the ultimate deformations, but also their intermediate values. This requires reliable diagrams "s–e” for all classes of concrete. The difficulties of measuring deformations in concrete subjected to peak load, corresponding to the prismatic strength, as well as main cracks that appeared under conditions of long-term step loading are highlighted. Variants of more accurate measurements are proposed. Development and implementation of the new standard GOST "Concretes. Methods for determination of complete diagrams" on the basis of the developed method for obtaining complete diagrams of concrete deformation under compression for the evaluation of ultimate deformability of concrete under compression are necessary.

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