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Effect Of Thermal Contact Resistance On The Heat Transfer In Plate Finned Tube Heat Exchangers, D. Taler
Effect Of Thermal Contact Resistance On The Heat Transfer In Plate Finned Tube Heat Exchangers, D. Taler
Heat Exchanger Fouling and Cleaning VII
Plate fin-and-tube heat exchangers are made by inserting oval tubes through sheet metal strips with stamped holes and then expanding the tubes slightly to cause pressure at the tube-to-strip contacts. The gap between the fin base and the outer tube surface may be filled with air or corrosion products causing a decline in the ability of plate fins to transfer heat. The contact resistance must be accounted for in the design and performance calculations of heat exchangers. In this paper, the thermal contact resistance of the fin-to-tube attachment is estimated from the condition that the dimensionless correlations for the Colburn …
Low Fouling Crude Oil Preheaters: Scrap Your Existing Conventional Crude Oil Preheaters, Replace Them By Low Fouling Heat Exchangers And Save Money, D.G. Klaren, E.F. De Boer, D.W. Sullivan
Low Fouling Crude Oil Preheaters: Scrap Your Existing Conventional Crude Oil Preheaters, Replace Them By Low Fouling Heat Exchangers And Save Money, D.G. Klaren, E.F. De Boer, D.W. Sullivan
Heat Exchanger Fouling and Cleaning VII
In a time that crude oil prices are constantly higher than US$ 60 per barrel, low fouling heat exchangers can reduce total fouling cost in all crude oil preheat trains in the world with a throughput of 74 Mn bpd by 90%. For 2006, this is a reduction from approximately US$ 11 Bn to US$ 1.3 Bn and a saving on annual fouling cost of US$ 9.7 Bn. Besides this saving on fouling cost, substantial additional savings can be realized on energy by a more ‘energy efficient’ design of the crude oil preheat train. The advantages of the low fouling …
Intelligent Discrimination Model To Identify Influential Parameters During Crystallisation Fouling, M.R. Malayeri, H. Müller-Steinhagen
Intelligent Discrimination Model To Identify Influential Parameters During Crystallisation Fouling, M.R. Malayeri, H. Müller-Steinhagen
Heat Exchanger Fouling and Cleaning VII
The introduction of redundant independent variables into any function approximation model, or the neglect of important variables, may result in a correlation with poor prediction and reduced reliability. This paper demonstrates that a novel integrated model of neural networks and genetic algorithms can deal with this problem robustly with good accuracy, while be far less time-consuming compared to lengthy conventional models Furthermore, a redundant variable input was imposed to the model to discern if the approach could identify it among other important variables. Genetic algorithms were exploited as a powerful optimisation tool for the selection of best set of inputs …
Evaluation Of Heat Transfer Boundary Conditions For Cfd Modeling Of A 3d Plate Heat Exchanger Geometry, T.M. Pääkkönen, M. Riihimäki, R. Ylönen, E. Muurinen, C.J. Simonson, R.L. Keiski
Evaluation Of Heat Transfer Boundary Conditions For Cfd Modeling Of A 3d Plate Heat Exchanger Geometry, T.M. Pääkkönen, M. Riihimäki, R. Ylönen, E. Muurinen, C.J. Simonson, R.L. Keiski
Heat Exchanger Fouling and Cleaning VII
In this paper fluid flow and heat transfer are modeled in a corrugated 3D plate heat exchanger geometry with a commercial computational fluid dynamics (CFD) program, Fluent 6.1.22 (Fluent Inc., Lebanon), in order to find out the most realistic heat transfer boundary conditions for a plate heat exchanger. The built-in boundary conditions of Fluent available for this case are Heat flux, Convection and Constant wall temperature. The CFD models are verified with correlations and experimental data obtained by a flat plate test equipment of which parameters can be calculated analytically. Deficiencies are found in all the built-in heat transfer boundary …
Fluid Dynamic Gauging In Duct Flows – Experiments And Cfd Simulations, T. Gu, Y.M.J. Chew, W.R. Paterson, D.I. Wilson
Fluid Dynamic Gauging In Duct Flows – Experiments And Cfd Simulations, T. Gu, Y.M.J. Chew, W.R. Paterson, D.I. Wilson
Heat Exchanger Fouling and Cleaning VII
The technique of fluid dynamic gauging (FDG) has been developed to measure the thickness of deformable foulant deposits on solid immersed in liquid, in real time and in situ, with a precision of ± 10 micron. Suction is imposed across a gauging nozzle; the flow rate of liquid through the nozzle allows calculation of the proximity of the nozzle to the surface of the deposit. The technique has been demonstrated by Tuladhar et al. (2000) to work well in quasi-static situations, where the bulk liquid is not moving apart from the gauging flow, and in duct flows. FDG in the …
Fouling During The Use Of ‘Fresh’ Water As Coolant- The Development Of A ‘User Guide’, S. J. Pugh, G. F. Hewitt, H. Müller-Steinhagen
Fouling During The Use Of ‘Fresh’ Water As Coolant- The Development Of A ‘User Guide’, S. J. Pugh, G. F. Hewitt, H. Müller-Steinhagen
Heat Exchanger Fouling and Cleaning VII
IHS ESDU recently published its latest ‘User Guide’ to fouling in heat exchange systems, for systems with fresh water as the coolant. ESDU 07006 [1] is the third in a group, following the development of the Crude Oil Fouling User Guide [2] issued in 2000 and the Seawater Fouling User Guide [3] issued in 2004. ESDU 07006 was developed by IHS ESDU over a period of five years under the guidance of the Oil Industry Fouling Working Party, a collaborative team of oil refiners, heat transfer equipment and services suppliers and Universities. It provides designers and operators of cooling water …
Metallic Micro Heat Exchangers: Properties, Applications And Long Term Stability, J.J. Brandner, W. Benzinger, U. Schygulla, S. Zimmermann, K. Schubert
Metallic Micro Heat Exchangers: Properties, Applications And Long Term Stability, J.J. Brandner, W. Benzinger, U. Schygulla, S. Zimmermann, K. Schubert
Heat Exchanger Fouling and Cleaning VII
Micro heat exchangers, which until recently have been implemented only at laboratory scale, are now being available for industrial applications. They are well known for their superior heat transfer properties due to the large surface-to-volume ratio. But there are little data available on the long term stability of these devices. In this paper application several application examples for micro heat exchangers made of stainless steel are presented. The devices consist of stainless steel foils providing numerous micro channels generated by mechanical micromachining or wet chemical etching. A number of the foils are arranged in a specific way and bonded together. …
Influence Of Different Surface Materials On The Fouling Process In A Microstructured Heat Exchanger Under Laminar Regime, W. Benzinger, J.J. Brandner, U. Schygulla, K. Schubert
Influence Of Different Surface Materials On The Fouling Process In A Microstructured Heat Exchanger Under Laminar Regime, W. Benzinger, J.J. Brandner, U. Schygulla, K. Schubert
Heat Exchanger Fouling and Cleaning VII
Microstructure devices are well known for their excellent performance with regard to heat and mass transfer. Microstructured heat exchangers show significant advantages in comparison with conventional heat exchangers. The unique properties of a microreaction system show high overall heat transfer coefficients for example. Small characteristic dimensions are in the order of a few hundred μm (Schubert et al., 1998, 2001; Worz et al, 1998). Due to the small dimensions, an increased pressure drop is combined with excellent heat transfer properties. But the small channels are prone to fouling processes. The accumulation of crystalline deposits is a severe problem. An additional …
Hitran® Wire Matrix Inserts In Fouling Applications, J.M. Ritchie, P. Droegemueller, M.J.H. Simmons
Hitran® Wire Matrix Inserts In Fouling Applications, J.M. Ritchie, P. Droegemueller, M.J.H. Simmons
Heat Exchanger Fouling and Cleaning VII
Fouling characteristics are dictated largely by the properties of the thermal and hydrodynamic boundary layers. As a result, fouling mitigation strategies must take into account the conditions in this region. hiTRAN® wire matrix tube inserts are a useful tool in altering the conditions near the tube wall, especially in the laminar and transition flow regions. This review paper considers Particle Image Velocimetry (PIV) and Laser Doppler Velocimetry (LDV) measurements, which were employed in order to show the hydrodynamic differences between plain tubes and those containing inserts. Measurements indicate that the wall shear rate in tubes containing hiTRAN® inserts operating in …
Biofouling Control In Heat Exchangers Using High Voltage Capacitance Based Technology, R. Romo, M. M. Pitts, N. B. Handagama
Biofouling Control In Heat Exchangers Using High Voltage Capacitance Based Technology, R. Romo, M. M. Pitts, N. B. Handagama
Heat Exchanger Fouling and Cleaning VII
Biofouling in industrial heat exchangers and piping systems is common in water from all sources. Problems generated by biofouling such as corrosion, sludge deposition and scale formation have a costly impact on industrial equipment and productivity. This paper describes an electronic approach using High Voltage Capacitance Based technology (HVCB) to control biofouling in industrial heat exchangers, focusing upon biofilm removal and the prevention of biofilm formation. Four different application case studies are presented in this paper in which the HVCB technology was used to control biofouling. The applications include an evaporative cooling wall in a greenhouse in Oracle, Arizona; a …
Cleaning Monitoring Using Controlled Nano-Vibrations, A. Pereira, J. Mendes, L.F. Melo
Cleaning Monitoring Using Controlled Nano-Vibrations, A. Pereira, J. Mendes, L.F. Melo
Heat Exchanger Fouling and Cleaning VII
The monitoring of fouling and cleaning has become very important in order to optimize production cycles, to increase the quality of the final product and to reduce environmental impacts. The aim of the study here presented was to use the MSS – Mechatronic Surface Sensor, to detect the cleaning end-point of hair shampoo removal under different cleaning conditions. It was found that this new monitoring tool was able to clearly identify when the equipment was cleaned, producing different cleaning curves for different cleaning conditions.
Electrochemical Impedance And Digital Image Methods To Detect Initial Deposition Of Microorganisms, H. Men, S. W. Mu, Z. W. Lu, Y. L. Chen, S.R. Yang, Y. P. Jia, S. X. Cao
Electrochemical Impedance And Digital Image Methods To Detect Initial Deposition Of Microorganisms, H. Men, S. W. Mu, Z. W. Lu, Y. L. Chen, S.R. Yang, Y. P. Jia, S. X. Cao
Heat Exchanger Fouling and Cleaning VII
Microorganism in industrial cooling water can cause corrosion and biofouling. Electrochemical impedance method and digital image method (DIM) were used to detect quantitatively iron bacteria and heterotrophic bacteria. Microorganism growth and metabolism can change the impedance of culture medium. The detection time of impedance variation lie in the function relationship with the logarithm of bacteria concentration. 7-million-pixel CCD sensor was used to shoot the shape of microorganism in order to count the number. Compared with most probable number (MPN) method, the detection time of electrochemical impedance is shortened. The DIM reduces the bacteria counting time and the inaccuracy associated with …
Slag Monitoring System For Combustion Chambers Of Steam Boilers, J. Taler, D. Taler
Slag Monitoring System For Combustion Chambers Of Steam Boilers, J. Taler, D. Taler
Heat Exchanger Fouling and Cleaning VII
The computer based boiler performance system, presented in this paper, has been developed to provide a direct and quantitative assessment of furnace and convective surface cleanliness. Temperature, pressure and flow measurements and gas analysis data are used to perform heat transfer analysis in the boiler furnace and evaporator. Power boiler efficiency is calculated using an indirect method. The on-line calculation of the exit flue gas temperature in a combustion chamber allows for an on-line heat flow rate determination, which is transferred to the boiler evaporator. Based on the energy balance for the boiler evaporator, the superheated steam mass flow rate …