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Sep 21 17

Fouling Results of Vipertex 1EHT tubes in Crude presented at the HTRI 2017 Global Conference & Annual Meeting of Stockholders Ottawa, ON, Canada | September 18 – 21, 2017

by vipertex

Results of a  fouling study that  took place with Shell Oil was presented at HTRI’s annual meeting. The study evaluated heat transfer, shear and the amount of fouling that occurred under fouling conditions using crude oil.

https://www.htri.net/events/185

 

Sep 21 17

Keynote Paper Presented at PRES17 a Process Engineering Conference on Vipertex Tubes

by vipertex

Results from a study that evaluated the performance of Vipertex tubes have been presented at PRES17 and also been published in Chemical Engineering Transactions (CET)

 

 CHEMICAL ENGINEERING TRANSACTIONS

 

VOL. 61, 2017

Guest Editors: Petar S Varbanov, Rongxin Su, Hon Loong Lam, Xia Liu, Jiří J Klemeš

Copyright © 2017, AIDIC Servizi S.r.l.
ISBN 978-88-95608-51-8; ISSN 2283-9216

Condensation and Evaporation Characteristics of Flows Inside Three Dimensional Vipertex Enhanced Heat Transfer Tubes

Results are presented here from an experimental investigation of condensation and evaporation heat transfer that compares the performance of three dimensional (3-D) enhanced heat transfer tubes to the performance of a smooth surface tube. The equivalent outer diameter of all the tubes was 12.7 mm with an inner diameter of 11.5 mm. Both the inner and outer surfaces of the 3-D tubes are enhanced by a primary enhancement and a background pattern made up by an array of dimples. Experimental runs were performed using R410A as the working fluid, over the quality range of 0.2 – 0.9. The test apparatus included a horizontal, straight test section with an active length heated by water circulated in a surrounding annulus. Constant heat flux was maintained and refrigerant quality varied.

For evaporation, the heat transfer coefficient ratio of the 3-D tubes (comparing the heat transfer coefficient of the enhanced tube to that of a smooth tube) is in the range of 1.1 – 1.80 for a mass flux rate that ranges from 80 to 180 kg/m2s. For condensation, the heat transfer coefficient ratio range is 1.1 – 1.75 for mass flux that ranges from 80 to 260 kg/m2 s. Frictional pressure drop values for the enhanced tubes show some variation. Heat transfer enhancement on the inner surface of the 3-D tubes increases the surface area and interfacial turbulence; producing flow separation, secondary flows and a higher heat flux from the wall to the working fluid.

Enhanced heat transfer tubes are important options to be considered in the design of high efficiency systems. A wide variety of industrial processes involve the transfer of heat energy during phase change and many of those processes employ old designs. These processes are ideal candidates for a redesign that could achieve improved process performance. These three dimensional enhanced tubes recover more energy and provide an opportunity to advance the design of many heat transfer products.

Aug 21 17

Vipertex EHT Tube Results Presented at ASME HT2017 Summer Heat Transfer Conference

by vipertex

Condensation and Evaporation results for 1EHT and 2EHT tubes have been presented at the ASME  Summer Heat Transfer Conference (HT2017)

 

HEAT TRANSFER CORRELATIONS FOR CONDENSATION IN THREE-DIMENSIONAL SURFACE ENHANCED HEAT TRANSFER TUBES

HT2017-4927

 

EXPERIMENTAL STUDY ON HEAT FLUX EFFECT ON EVAPORATION IN TWO DIMPLE-GROOVED TUBES

HT2017-4910

Apr 13 17

ASME Code Case Approval Using Vipertex Tubes

by vipertex

ASME Code Case 2877 details the design of heat exchangers using Vipertex tubes.

Apr 4 17

EVALUATION OF HEAT EXCHANGER DESIGNS USING ENHANCED HEAT TRANSFER TUBES

by vipertex

Presented at the 2017 American Society of Thermal and Fluids Engineers (ASTFE) Conference and 4th International Workshop on Heat Transfer (IWHT)

Enhanced heat transfer tubes are widely used in many areas in order to reduce cost and create a smaller application footprint. A numeric study was performed that predicts performance of industrially relevant heat exchangers using the Vipertex model 1EHT enhanced heat transfer tubes and compares them to the performance of heat exchangers that use smooth surface tubes. The Vipertex model 1EHT tubes can be employed to design more efficient heat exchangers while at the same time decreasing the required mass flow rate and allowing the heat exchangers to operate at lower flows; and if needed, they also can reduce the footprint of the heat exchange device. In addition several cases also compared performance to other enhanced tubes. Some of the low fin options performed better for some cases; while for other cases the 1EHT tube performed better. Vipertex 1EHT tubes produced the most consistent performing option for all the cases considered and demonstrate that it is a good overall tube choice for a wide range of conditions. Through the use of 1EHT enhanced heat transfer tubes, optimized design can reduce the number of tubes while maintaining design requirements. In some designs, the physical size of the heat exchanger can be reduced while maintaining design requirements. Additional case studies for a wider range of conditions will be the subject of future studies.

 

https://www.astfe.org/conferences/tfec2017/tfec2017_conference_technical_program.pdf

 

Feb 2 17

Paper published on the Vipertex 1EHT tube by authors from The Petroleum Institute and Isotherm Inc.

by vipertex

The following research paper has recently been published in Applied Thermal Engineering detailing results of the Vipertex 1EHT tube.

Volume 103,  2016, Pages 639-650.

 

Geometric optimization for thermal–hydraulic performance of dimpled
enhanced tubes for single phase flow

Ming Li, Tariq S. Khan, Ebrahim Al Hajri
Department of Mechanical Engineering, The Petroleum Institute, Abu Dhabi, United Arab Emirates

 

Zahid H. Ayub         Isotherm Inc., Arlington, USA

 

Enhanced surfaces have larger heat transfer surface area and offer increased turbulence level hence allowing higher heat exchange performance. In this study, numerical simulations are conducted to simulate geometric design optimization of enhanced tubes for optimal thermal–hydraulic performance. The simulations are validated with experimental data. Two and three dimensional steady incompressible turbulent flow in dimpled enhanced tube is numerically studied using realizable k– e method. The pressure– velocity coupling is solved by Semi-Implicit Method for Pressure Linked Equations Consistent (SIMPLEC) algorithm. Results show that dimples on tube surface present high heat transfer performance. Compared to staggered configuration, the in-line dimples arrangement provided better overall heat exchange characteristics.
The geometric parameters like dimple shape, depth, pitch and starts are found to have significant effects on overall heat exchange performance while the dimple diameter has insignificant effect on thermal performance.

 

Jan 10 17

Vipertex Tubes Produced under ASTM 1098

by vipertex

A new ASTM standard has recently been approved to produce Vipertex EHT tubes .
It is titled Standard Specification for Welded Austenitic Alloy Steel Boiler, Superheater, Condenser, and Heat Exchanger Tubes with Textured
Surface(s)
This allows the Vipertex tubes to be produced to the roughly the same standards as ASTM 249

Dec 7 16

Vipertex 2EHT Results Published in the Journal of International Communications in Heat and Mass Transfer Journal

by vipertex

Results from a study that evaluated the performance of 2EHT tubes has just been published in a heat transfer journal.

Title:Experimental study on condensation and evaporation flow inside horizontal three dimensional enhanced tubes

Journal title:  International Communications in Heat and Mass Transfer Journal.  Volume 80, Page 30-40, 2017.

 

Experimental investigations of tube side condensation and evaporation in two 3-D enhanced heat transfer (2EHT) tubes were compared to the performance of a smooth surface copper tube. The equivalent outer diameter of all the tubes was 12.7 mm with an inner diameter of 11.5 mm. Both the inner and outer surfaces of the 2EHT tubes are enhanced by longitudinal grooves with a background pattern made up by an array of dimples/embossments. Experimental runs were performed using R410A as the working fluid, over the quality range of 0.2–0.9. 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 1.11–1.43 (with an enhanced surface area ratio of 1.03) for mass flux rate that ranges from 80 to 200 kg/m s.  For condensation, the heat transfer coefficient ratio range is 1.1– 1.16 (with an enhanced surface area ratio of 1.03) for mass flux that ranges from 80 to 260 kg/m s. Frictional pressure drop values for the 2EHT tubes are very similar to each other. Heat transfer enhancement in the 2EHT tubes is mainly due to the dimples and grooves in the inner surface that create an increased surface area and interfacial turbulence; producing higher heat flux from wall to working fluid, flow separation, and secondary flows. A comparison was performed to evaluate the enhancement effect of the 2EHT tubes using a defined performance factor and this indicates that the 2EHT tubes provides a better heat transfer coefficient under evaporation conditions.

 

Nov 10 16

Comparison of heat exchanger designs using Vipertex 1EHT enhanced heat transfer tubes

by vipertex

A numeric study was performed that compares the performance of heat exchangers using the Vipertex  enhanced heat transfer tubes (model 1EHT) to the performance of heat exchangers that use smooth surface tubes. Heat transfer enhancement is an important factor in obtaining energy efficiency improvements in all heat transfer applications. Surface enhancement of the 1EHT tube is accomplished through the use of the primary dimple enhancement and the secondary background pattern made up of petal arrays. Utilization of enhanced heat transfer tubes is an effective method that is utilized in the development of high performance thermal systems. Vipertex™ enhanced surfaces, have been designed and produced through material surface modifications that produce flow optimized heat transfer tubes that increase heat transfer. Current energy demands and the desire to increase efficiencies of systems have prompted the development of enhanced heat transfer surfaces.

Enhanced heat transfer tubes are widely used in many areas (refrigeration, air-conditioning, petro-chemical, chemical, etc.) in order to reduce cost and create a smaller application footprint. A new type of enhanced heat transfer tube has been created; therefore it is important to investigate relevant heat exchanger designs using the Vipertex enhanced surface tube in industrial applications and compare that performance to other tubes. Results include design characteristics and performance predictions using the design simulations produced using HTRI Exchanger Suite (2016). Performance for all cases considered using the Vipertex tube predicted over performance when compared to a smooth tube design. Vipertex tubes produced higher performance and more efficient designs.

 

 

Published and Presented at the 22nd International Congress of Chemical and Process Engineering CHISA 2016 and the 19th Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction PRES 2016

Chemical Engineering Transactions, 2016, Vol 52, Pg 115,  DOI: 10.3303/CET1652020

Apr 4 16

Comparison of condensation and evaporation heat transfer on the outside of smooth and enhanced 1EHT tubes

by vipertex

Recent results on the condensation and evaporation on the outside of the Vipertex 1EHT has been published in Applied Thermal Engineering, doi:10.1016/j.applthermaleng.2016.03.036.

Comparison of condensation and evaporation heat transfer on the outside of smooth and enhanced 1EHT tubes

 

Results are presented here from an experimental investigation that evaluated the outside condensation and evaporation heat transfer that took place on a 12.7 mm (0.5 in.) OD horizontal copper tube. Evaporation conditions include a mass flux that ranged from 10 to 40 kg/m2 s; with an inlet quality of 0.1 (±0.05); outlet quality of 0.8 (±0.05); and a nominal evaporation temperature of 279 K.  Average evaporation heat transfer coefficients for R22 and R410A on the 1EHT tube are in the range of one to four times greater than those of a smooth tube.