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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.

 

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.

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