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Apr 4 16

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 experimental and numeric results of the Vipertex 1EHT tube.

Volume 101, 25 May 2016, Pages 38–46

Single phase heat transfer and pressure drop analysis of a dimpled
enhanced tube
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

A non-dimensional performance evaluation criterion (PEC) was used to assess the thermal-hydraulic performance of heat transfer enhancement achieved with the Vipertex 1EHT enhanced tube. Based on the experimental data, Nusselt number and friction factor estimation correlations were proposed for the enhanced tube. Simulations were carried out to obtain heat transfer and pressure drop characteristics of smooth and enhanced tubes, using commercial Fluent.

Sep 14 15

FLOW VISUALIZATION AND COMPARISON OF THE EVAPORATION HEAT TRANSFER COEFFICIENT FOR SMOOTH AND ENHANCED SURFACE 1EHT HORIZONTAL TUBES

by vipertex

Flow visualization of flows near a heat transfer tube and evaporation heat transfer results of Vipertex 1EHT tubes are compared to  Smooth Tubes have been presented  at ECCE10 (10th European Congress of Chemical Engineering).

 

Visualizations of Pool Boiling in Water for a 1EHT Tube –  Vectors indicating Flow Speed of Particles

smooth with vectors

 

Visualizations of Pool Boiling in Water for a 1EHT Tube –  Vectors indicating Flow Speed of Particles
cavities with vector

 

The evaporation heat transfer coefficient enhancement ratio (for the range considered for flows using R410a), for the 1EHT tube is approximately 1.4

 

 

Aug 31 15

Joint Paper Published with Shell Oil on the advantages of Vipertex 1EHT under fouling conditions

by vipertex

The results of a joint research project between Shell Oil and Rigidized Metals has recently been published in the Journal of Enhanced Heat Transfer. Heat Transfer advantages of the 1EHT tube for crude fouling conditions are discussed.

 

HEAT TRANSFER PERFORMANCE EVALUATION CRITERIA APPLIED TO A TEXTURED TUBE SURFACE FOR CRUDE OIL

Himanshu Joshi
Shell Global Solutions (US) Inc.
David Kukulka
Ridigized Metals Corp.
Srikanth Kummari
Shell India Markets Pvt. Ltd.

 

The evaluation shows that depending on the applied constraints, different benefits can be obtained using Vipertex tubes, inculding: – a heat duty increase of up to 19%, an 18-30% reduced flow rate to achieve the same heat duties, or a change in the geometry to achieve a 8-9% increase in heat transfer at the same pumping power.

 

 

Jul 30 15

COMPARISON OF THE EVAPORATION AND CONDENSATION HEAT TRANSFER COEFFICIENTS ON THE OUTSIDE OF SMOOTH, MICRO FIN AND VIPERTEX 1EHT ENHANCED HEAT TRANSFER TUBES

by vipertex

Published and Presented at HEFAT2015  11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, pp.803-812

July 2015

An experimental investigation was performed to evaluate condensation and evaporation  heat transfer on the outside of  a smooth tube, herringbone micro fin tube and the Vipertex 1EHT enhanced  heat transfer tube as a function of  mass flux. Heat transfer enhancement is an important factor in obtaining energy efficiency improvements in two phase heat transfer applications. Utilization of enhanced heat transfer tubes is an effective enhancement method that is utilized in the development of high performance thermal systems. Vipertex™ enhanced surfaces have been designed and produced through material surface modifications, creating flow optimized heat transfer tubes that increase heat transfer. Heat transfer processes that involve phase-change processes are typically efficient modes of heat transfer; however current energy demands and the desire to increase efficiencies of systems have prompted the development of enhanced heat transfer surfaces that can be used in processes involving evaporation and condensation.

Surface enhancement of the 1EHT tube is accomplished through the use of a primary dimple enhancement coupled with a secondary background pattern made up of petal arrays. Enhancement of the herringbone is accomplished through the use of microfins. Convective condensation heat transfer and pressure loss characteristics were investigated using R410A on the outside of: (i) a smooth tube (outer diameter 12.7 mm); (ii) an external herringbone tube (fin root diameter 12.7 mm); and (iii) the 1EHT tube (outer diameter 12.7 mm) for mass flux ranging from 8 to 50 kg/ (m2 s); at a saturation temperature of 318 K; with an inlet quality of 0.8 and an outlet quality of 0.1. For these conditions, both the 1EHT tube, and the herringbone tube did not perform as well as the smooth tube. This was an unexpected result.

Additionally the study also included a determination of the evaporation heat transfer coefficients using R410A on the outside of the same three tubes. The nominal evaporation temperature was 279 K; for a mass flux that ranged from 10 to 40 kg/m2 s; with an inlet quality of 0.1 and the outlet quality of 0.8.  Excellent heat transfer performance is demonstrated by the 1EHT tube showing an enhancement ratio of approximately 1.4. Evaporation heat transfer coefficient enhancement values for the herringbone tube ranges from 1.5 to 2.2. For the considered conditions, both the herringbone and 1EHT tubes have higher pressure drops than smooth tubes.

Microfins, surface roughness and three dimensional enhanced surfaces are often incorporated on the surface of tubes in order to enhance heat transfer performance. Under many conditions, enhanced surface tubes can recover more energy and provide the opportunity to advance the design of many heat transfer products. Enhanced heat transfer tubes are widely used in refrigeration and air-conditioning applications in order to reduce cost and create a smaller application footprint. A new type of enhanced heat transfer tube has been created using dimples/protrusions with secondary petal arrays; therefore it is important to investigate the heat transfer characteristics of the new Vipertex 1EHT enhanced surface tube and compare it to other tubes.

 

Feb 17 15

A General Correlation for Condensation Heat Transfer in Micro-Fin for Herringbone and Dimple-Texture Tubes

by vipertex

Published  ICNMM2015

InterPACKICNMM2015-48198

Session 5-5-1

A General Correlation for Condensation Heat Transfer in Micro-Fin for Herringbone and Dimple-Texture Tubes

 

An experimental investigation was performed to evaluate the condensation characteristics inside smooth, herringbone and dimple-texture (Vipertex 1EHT) tubes with the same outer diameter (12.7 mm) using R22 and R410a refrigerants, for a mass flux range from 81 to 178.5 kg/m²s. The condensation saturation temperature is 47℃; with an inlet quality of 0.8 and an outlet vapor quality of 0.2. Results indicate that the condensation heat transfer coefficient of the herringbone tube was approximately 3 times that of the smooth tube for R22 and a factor of 2.3 for R410a. Multipliers for the dimple tube heat transfer coefficient is approximately 2 times that of a smooth tube for R22 and 1.8 for R410a. Four previously reported correlations are used to compare heat transfer coefficient measurements in the plain tube; while a new equation is proposed to predict the heat transfer coefficient in the herringbone tube.

Keywords: dimple enhanced tube, Herringbone tube, Condensation, Heat Transfer Coefficient, Correlation.

Feb 17 15

Evaporation Heat Transfer Characteristics on the Outside of Horizontal Smooth, Herringbone and Enhanced Surface 1EHT Tubes

by vipertex

Published  ICNMM2015

InterPACKICNMM2015-48199

Session 6-2-5

Evaporation Heat Transfer Characteristics on the Outside of Horizontal Smooth, Herringbone and Enhanced Surface 1EHT Tubes

 

Abstract

An experiment investigation was performed using R410A in order to determine the single-phase and evaporation heat transfer coefficients on the outside of (i) a smooth tube; (ii) herringbone tube; and (iii) the newly developed Vipertex enhanced surface 1EHT tube; all with the same external diameter (12.7 mm). The nominal evaporation temperature is 279 K, with inlet and outlet qualities of 0.1 and 0.8. Mass fluxes ranged from 10 to 40 kg/m²s. Results suggest that the 1EHT tube has excellent heat transfer performance but a higher pressure drop when compared to a smooth tube. Evaporation heat transfer coefficient for the 1EHT is lower than the herringbone tube and the pressure drop is almost the same.

Keywords: enhanced surface heat transfer tube, herringbone tube, evaporation, pressure drop, heat transfer

 

Feb 17 15

Condensation Heat Transfer Characteristics on the Outside of Horizontal Smooth, Herringbone and Enhanced Surface 1EHT Tubes

by vipertex

Published and presented  ICNMM2015 

InterPACKICNMM2015-48196

Session 5-5-1

 

Condensation Heat Transfer Characteristics on the Outside of Horizontal Smooth, Herringbone and Enhanced Surface 1EHT Tubes

 

Abstract

Heat transfer enhancement plays an important role in improving energy efficiency and developing high performance thermal systems. Phase-change heat transfer processes   take place in thermal systems; typically heat transfer enhanced tubes are used in these systems and they are designed to increase heat transfer coefficients in evaporation and condensation. Enhanced heat transfer tubes are widely used in refrigeration and air-conditioning applications in order to reduce cost and create a smaller footprint of the application. A new type of enhanced heat transfer tube has been created using dimples/protrusions and secondary petal arrays has been developed, therefore it is important to investigate the condensation heat transfer characteristics of the Vipertex 1EHT enhanced surface tube and compare it to other tubes.

Convective condensation heat transfer and pressure loss characteristics were investigated for R410A on the outside of: (i) a smooth tube (outer diameter 12.7 mm); (ii) an external herringbone tube (fin root diameter 12.7 mm); and (iii) the 1EHT tube (outer diameter 12.7 mm) for very low mass fluxes. Data was obtained for values of mass flux ranging from 8 to 50 kg/ (m2 s); at a saturation temperature of 318 K; with an inlet quality of 0.8 and an outlet quality of 0.1. In a comparison of heat transfer at a low mass flux, both the 1EHT tube and the herringbone tube did not perform as well as the smooth tube.

Microfins, roughness and dimples are often incorporated into the inner surface of tubes in order to enhance condensation heat transfer performance. Under many conditions, enhanced surface tubes can recover more energy and provide the opportunity to advance the design of many heat transfer products.

Keywords: enhanced surface tube, condensation, heat transfer

 

 

 

Feb 17 15

Condensation and evaporation heat transfer characteristics in horizontal smooth, herringbone and enhanced surface EHT tubes

by vipertex
  1. Published in      International Journal of Heat and Mass Transfer

Full bibliographic details:               International Journal of Heat and Mass Transfer, Vol 85c,  (2015) pp. 281-291

DOI information:              10.1016/j.ijheatmasstransfer.2015.01.115

http://www.sciencedirect.com/science/article/pii/S0017931015001337

 

 

Condensation and evaporation heat transfer characteristics in horizontal smooth, herringbone and enhanced surface EHT tubes

 

Abstract

An experimental investigation was performed to evaluate convective condensation and evaporation of R22, R32 and R410A inside a smooth tube (inner diameter 11.43 mm), a herringbone tube (fin root diameter 11.43 mm) and a newly developed enhanced surface EHT tube (inner diameter 11.5 mm) at low mass fluxes. The inner surface of the EHT tube is enhanced by dimple/protrusion and secondary petal arrays. For condensation, the heat transfer coefficient of the herringbone tube is 2.0 to 3.0 times larger than a smooth tube and the EHT tube is 1.3 to 1.95 times that of the smooth tube. The heat transfer enhancement ratios of the herringbone tube and the EHT tube are larger than their respective inner surface area ratios. Mass flux has a non-monotonic relation with the condensation heat transfer coefficient in the herringbone microfin tubes; this was especially evident for R32 and R410A. For evaporation, the EHT tube provides the best evaporation heat transfer performance for all the three refrigerants; this is mainly due to the heat transfer enhancement produced from the larger number of nucleation sites, increased interfacial turbulence, boundary layer disruption, flow separation and secondary flow generation caused by the dimple and petal arrays. The evaporation heat transfer coefficient of the herringbone tube is only slightly higher than that of the smooth tube. Overall, the EHT tube provides increased heat transfer enhancement for both condensation and evaporation.

Keywords: Herringbone tube, condensation, evaporation, heat transfer enhancement

 

 

 

 

Feb 17 15

Comparison of Tubeside Condensation and Evaporation Characteristics of Smooth and Enhanced Heat Transfer 1EHT Tubes

by vipertex

This has been recently published  in Applied Thermal Engineering

http://www.sciencedirect.com/science/article/pii/S1359431115000915

reference:  http://dx.doi.org/10.1016/j.applthermaleng.2015.01.066

 

Comparison of Tubeside Condensation and Evaporation Characteristics of Smooth and Enhanced Heat Transfer 1EHT Tubes

David J. Kukulka*, Rick Smith, Wei Li

 

Results are presented here from an experimental investigation that was performed to evaluate the inside condensation and evaporation heat transfer of R410A, R22 and R32 that took place in a 12.7 mm (0.5 in) O.D. horizontal copper tube at low mass fluxes. Tubes considered in this evaluation consisted of a smooth tube (inner diameter 11.43 mm) and a newly developed enhanced surface Vipertex™  1EHT tube. Heat transfer enhancement is an important factor in obtaining energy efficiency improvements in a variety of heat transfer applications. Utilization of enhanced heat transfer tubes is often utilized in the development of high performance air conditioning and refrigeration systems. Vipertex™ has designed and produced these surfaces through three dimensional material surface modifications which produces flow optimized, enhanced heat transfer tubes that increase heat transfer. Heat transfer enhancement plays an important role in improving energy efficiencies and developing high performance thermal systems. This study details the evaluation of the in-tube evaporation and condensation that takes place in these tubes over a wide range of conditions.

The test apparatus utilized included a straight horizontal test section with an active length heated by water circulated in the surrounding annulus. Constant heat flux was maintained and refrigerant quality varied. In-tube evaporation measurements of R22, R32 and R410A are reported for evaporation at 10 OC with mass flow rates in the range of 15 to 40 kg/h. Single phase measurements are reported for mass flow rates from 15 kg/h to 80 kg/h. Condensation tests were conducted at a saturation temperature of 47OC, with an inlet quality of 0.8 and an outlet quality of 0.1. In a comparison to smooth tubes, the average heat transfer coefficients for the Vipertex 1EHT tube exceeded those of a smooth tube. Average evaporation and condensation heat transfer coefficients for R22, R32 and R410A in the 1EHT tube are approximately two times greater than those of a smooth tube.

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. Many of those processes employ old technology; this makes those processes ideal candidates for a redesign using enhanced surfaces that would produce improved process performance. Vipertex 1EHT enhanced tubes recover more energy and provide an opportunity to advance the design of many heat transfer products.

Keywords:  Enhanced Heat Transfer Surfaces, Enhanced Tubes, Condensation, Evaporation, Three Dimensional Heat Transfer Surfaces

Nov 26 14

Lots of improvements on the way!

by vipertex

As we continue to grow our business and our team within Vipertex, we want to be sure we are always bringing you the most up-to-date information on our products, testing, services and solutions. That said, you may have noticed the redirect of our website to now reside within our parent company, Rigidized Metals Corporation.

In the coming weeks and months, we plan to bring you an updated, more informative website with an even wider range of offerings and services that our products can provide. We thank you for your patience!