Enhanced Heat Transfer Surfaces Research Articles

Experimental investigations on a coupled metal hydride based thermal energy storage system

Thermal energy storage using coupled metal hydride reactors is attractive because it offers several advantages such as one-time hydrogen loading, high thermal storage density, compactness and possibility of simultaneous heating and cooling. This study presents experimental investigations on a coupled metal hydride based thermal energy storage system. Based on compatibility criteria of hydrides described in this work, LaNi4.25Al0.75 for thermal energy storage and La0.75Ce0.25Ni5 for hydrogen storage were chosen. The study employed two novel cartridge type coupled reactors with enhanced heat transfer surfaces. The effects of heat source and ambient temperatures on the system performance were investigated. The study reveals that coupled hydride systems with suitable pairs of hydrides can deliver high energy storage capacities at good thermal efficiencies. The heat output of 227.7 kJ was achieved with a heat transfer rate of 130.7 W at 55.7 % efficiency. The hydrogen storage alloy exhibited good compatibility with the energy storage alloy with fast hydrogenation and dehydrogenation. It also produced a cooling effect of 171.8 kJ while desorbing hydrogen.

Transient thermal performance enhancement of phase change material (RT82) through novel pin arrangements under varied gravity conditions

Phase change materials (PCMs) are an effective medium for thermal management of avionics because of their ability to absorb, store, and release high heat loads while operating within narrow temperature range in confined spaces. Despite hosting several benefits, PCM systems suffer from low thermal conductivity issue. Strategically placed fins in a volume filled with PCM has the potential to significantly improve the transient thermal performance of PCMs by improving the overall thermal conductivity and providing enhanced heat transfer surface area. Furthermore, avionics can be subjected to varying gravity conditions during flight that can have significant influence on the overall thermal performance of PCMs. This emphasizes the need to characterize the PCM performance under various gravity conditions that can impart different buoyancy induced effects in a confined system. To this end, numerical investigation to study the melting characteristics of PCM-fin configuration subjected to three different gravity conditions, i.e., (a) microgravity, (b) terrestrial gravity, and (c) hypergravity, is conducted. The influence of these three conditions on the performance of PCM-fin combination configuration is investigated and finally the temperature field, melt fraction, and melting time is reported. The performance of PCM-fin system is compared with the corresponding PCM-only configuration to highlight the benefits of adding fins under each investigated gravity condition.

Thermodynamic optimisation of solar thermal Brayton cycle models and heat exchangers using particle swarm algorithm

In this work, three variants of the Brayton cycle incorporating concentrated solar technologies and dual regenerative systems are modeled. The first variant employs reheat, intercooling, and regeneration, the second applies intercooling and regeneration while the third case involves regeneration only. With the application of the entropy generation method and particle swarm algorithm (PSA), processes with the largest irreversibilities are noted, minimized and the geometric parameters of participating components are optimized. Results show that irreversibilities occurring in the systems were largely due to finite temperature differences within components. In all cases, the solar receiver and intercooler are the dominant and modest sources of entropy generation respectively. The regenerative system entropy generation is highest in the first case while decreasing in the second and third cases respectively. An improvement in the exergy/availability was observed in the first case, as the first and second law efficiency peaks at 44.9% and 59.68% respectively. Though, with a lower second law efficiency than the former, its percentage network output is equal to the first case at 43%. The aspect ratio, hydraulic diameter, and length of the receiver were observed to vary to enhance greater heat capture and increase the turbine inlet temperature (TIT). The high temperature (HT) regenerator had its geometric properties of a higher magnitude than the low temperature (LT) system as the waste heat recovery is aided by an enhanced heat transfer surface area. In comparison with the single regeneration system, the network output of the dual model was about 33.5% with a significant reduction in the entropy generated, creating a trade-off between operating the system for more power or less generation of irreversibilities.

STUDY ON COOLING OF HIGH PERFORMANCE SIC FEATURES

High-performance electronic parts are vital features in almost all modern motorized machines. These silicon components are significantly minimised, especially in transportation branch. Concentration of performance requires perfect cooling conditions. A fluid flow cooling by an active cooling circuit with heat sinks is a commonly used principle. Sufficient cooling and uniform temperature field on heat transfer area are crucial parameters for the sustainable function of Silicon-Carbide components. Producer of electric vehicles induces research in the field of coolers due to the requirements of installed SiC features. This study uses advanced CFD methods to analyse the current state of commonly manufactured heat exchangers and provides new approaches by CFD optimisation in combination with 3D printed replacement parts. Approach based on 3D print also allows design inspiration in natural principles. Biomimetic inspiration shows a wide range of thousands of years lasting optimisation made by nature. Research in this field can help us with the evolution of enhanced heat transfer surfaces. Developed coolers were examined by CFD techniques. Simulations of heat transfer are verified by laboratory measurement of prototype heatsinks. These techniques are presented on the unique design of a heat sink which was simulated, manufactured, and measured. The study shows CFD approaches, describes details of prototype measurement, and also deals with negative issues of metal 3D print.

Metaheuristics applied to the optimization of a compact heat exchanger with enhanced heat transfer surface

• A combined geometry of louvered fins and vortex generators is numerically simulated. • Parametric study on the influence of 8 independent variables on j and f. • Independent optimization of all the variables involved in the VG geometry. The heat exchanger compactness is a key factor in several engineering applications, such as, in automotive applications that use enhanced heat transfer surfaces on the air side to improve the convective heat transfer coefficient. In this study, a combined geometry of louvered fins and vortex generators is numerically simulated to optimize the thermohydraulic behavior of a compact heat exchanger. The influence of eight parameters of the enhanced surface on its thermohydraulic performance is analyzed. The thermohydraulic performance is evaluated through the Performance Evaluation Criterion, which relates the Colburn factor and the friction factor, i.e., the heat transfer enhancement and the increment of the pressure losses of the actual model with respect to a reference one. A metaheuristic tool, based on the NSGA-II genetic algorithms, combined with multi-objective optimization technique, is applied. The objective functions used in the optimization are obtained with numerical methods and computational fluid dynamics techniques. As a novelty, the optimization was carried out individually and under non-stationary flow conditions, for a total of eight magnitudes associated with the vortex generators. The optimized geometry is able to enhance the convective heat transfer between 6.55% and 19.63%, with an increase in pressure losses varying from 10.95% to 20.67% depending on the Reynolds number.

Maximum benefits from the use of enhanced heat transfer surfaces

The paper presents a critical review of the performance evaluation criteria (PEC) developed by Webb (Webb, 1981). These criteria evaluate the benefits that could be obtained in heat exchangers if their surfaces and inserts are designed to enhance the heat transfer, particularly in two-fluid heat exchangers in single-phase flow. This study revealed that the imposed constraint for fixed pumping power in the comparison of the augmented channel with the reference one is a major obstacle to achieving greater benefit. Accordingly, the elimination of the constraint of fixed pumping power and the objective of reduced pumping power decreases substantially the criteria of Webb. A new constraint related to the fixed augmentation entropy generation number has been involved replacing the constraint of fixed pumping power. The pumping power can be left to increase until the augmentation entropy generation number is less than unity. The maximum benefit can be obtained when the augmentation entropy generation number reaches the value of unity. The use of greater in tube heat transfer enhancement (with the use of compound heat transfer enhancement techniques instead of simple ones), and with an enhanced outer tube surface of the augmented exchanger is a useful instrument to increase the benefits, only if the augmentation entropy generation number does not cross the frontier of unity.

On the design of Phase Change Materials based thermal management systems for electronics cooling

This work aims at explaining the effect of the operating conditions on the performance of passive electronic thermal management systems based on Phase Change Materials. The low thermal conductivity of the Phase Change Materials is usually felt as one of their major limitations that hinders the effective heat transfer capability of the whole passive system. However, the present study experimentally demonstrates that the real improvement due to the use of enhanced heat transfer surfaces depends upon the operating conditions. The experimental tests were run on a latent thermal management system based on a paraffin wax with a 70 °C phase change temperature embedded in two different samples: an aluminum 3D pyramidal periodic structure having a porosity of 0.95 and a cell dimension of 10 mm realized via additive manufacturing, and an empty sample used as reference. The system was experimentally tested under several working conditions to simulate the real operation of an electronic device, including complete melting/solidification cycle and intermittent operations at different ambient temperatures, in natural and forced convection. The main outcome of the present study is that, when considering the junction temperature, the use of the enhanced surface does not always lead to an improvement of the heat transfer performance especially during fast intermittent operations and thus the maximum effective thermal conductivity cannot be always considered the main design objective. A novel integrated design approach should include the properties of the Phase Change Material, the system requirements and the real operating conditions.

Flow-Controlled Spray Cooling Approaches for Dynamic Thermal Management

Abstract Two-phase spray cooling is considered as one of the most promising thermal management techniques characterized by high heat transfer coefficient (HTC) and critical heat flux (CHF), as well as near-uniform temperatures on target surface. Normally, spray cooling systems feature steady flow rate and continuous spray, and are designed to satisfy the maximum expected heat load. However, if the heat load varies due to operating conditions, such as cold starts and pulsing power cycles, a spray cooling system uses excessive coolant most of the time, and causes low cooling efficiencies because of lower utilization of phase-change heat transfer and higher pumping power. This study aimed to investigate variable and intermittent flow spray cooling characteristics for dynamic thermal management. Variable flow spray cooling scheme requires control of pump input voltage (or speed), and intermittent flow spray cooling scheme requires control of solenoid valve duty cycle and frequency. Tests were conducted on a closed-cycle system with HFE-7100 dielectric coolant at varying liquid flow rate and subcooling conditions, and using smooth and enhanced heat transfer surfaces. Results, compared to a baseline performance from steady flow case, indicated that the variable flow spray cooling conditions achieve similar cooling performance at low and moderate heat fluxes, while the intermittent flow spray conditions result in high temperature penalty and much lower CHF.

Capillary-assisted evaporation characteristics of TiO2-CNT-Cu-nanocomposite-coated plates and finned plates

The present study involves the experimental investigation of capillary-assisted evaporation on nanocomposite-coated plates and finned structured plates, which were vertically installed on the refrigerant pool. To enhance the capillary action, i.e., climbing level of the thin refrigerant film, we proposed two approaches: 1) TiO2-CNT-Cu-nanocomposite-coated plate enhanced porosity and hydrophilicity as well as the thermophysical properties of the heat transfer surface. 2) Machined-finned structures were also developed on a bare copper plate to enlarge the contact area between the thin refrigerant film and the finned walls. A semi-flooded capillary-assisted evaporator was tested with the proposed enhanced heat transfer surfaces; herein, both the capillary-assisted evaporation and liquid natural convection evaporation occurred simultaneously. Results of wettability test on the nanocomposite-coated surfaces with distilled-water droplets revealed that the TiO2-CNT-Cu-nanocomposite-coated surface exhibited superhydrophilic characteristic. The experimental results illustrated that both the superhydrophilic surfaces achieved by the nanocomposite coating on the bare Cu plate and the finned plates enhanced the evaporation heat transfer by the formation of the liquid thin-film on the heat transfer surface. The filling level of the refrigerant pool for the semi-flooded evaporation test plate was also considered as the main factor for optimizing the capillary-assisted evaporation. As a result, the values of the peak evaporation heat transfer for all the tested plates were determined in terms of the filling levels. It was noteworthy that at a certain filling level, the upper body of the test plate was completely occupied by the highest height of the ultra-thin refrigerant film and the underbody was fully used for the liquid natural convection. The future work will include the evaporation mechanism of the evaporation heat transfer on the nanocomposite-coated on the machined-finned structures.

Numerical investigation on the effect of fin design on the melting of phase change material in a horizontal shell and tube thermal energy storage

Abstract It has previously been proven that fins can significantly enhance the thermal performance of latent heat thermal energy storage (LHTS) units. Nevertheless, the magnitude of improvement, especially in a horizontal LHTS, is still less than that required to address some of the existing challenges in solar energy applications. The tendency of the phase change material (PCM) at the bottom of the horizontal storage to remain solid because of the absence of convection currents to promote heat transfer must be tackled practically for this technology to be viable in different thermal applications. Thus, the fin configuration around the circumference of the horizontal storage must be optimised to enhance the melting rate and therefore improving efficiency. In the present paper, the thermal performance during the melting process for PCM (RT-50) in a horizontal LHTS unit was studied numerically with a view to optimizing the fin configuration. The baseline case of bare heat transfer fluid (HTF) tubes was compared with finned surfaces with four different fin angles ( θ = 72 o , 60 o , 45 o and 30 o ) with four different heights (0.2, 0.4, 0.6 and 0.8 of the hydraulic radius of the annulus (Rh)). The average temperature of the PCM, its liquid fraction, and velocity distribution during the melting process were investigated. The numerical results showed that increasing fin height (using a fixed fin configuration: θ = 72 o ) significantly improved the thermal performance of the horizontal LHTS. When the fin height was varied from 0 (bare HTF tube) to 0.8 of Rh, a shortening of the total melting time by approximately 50% was observed. For this fin height 0.8 Rh, it was shown that having a smaller angle between the fins, with all of them mounted below the horizontal axis of the LHTS unit, led to significant enhancement in the thermal performance of the storage. This is because the enhanced heat transfer surfaces are targeted to the regions of the LHTS unit where heat transfer is poorest in the bare tube configuration, as mentioned above. Thus, the total PCM melting time was reduced by 6.7%, 14.3%, 16.7% and 10.0% when the fin angle was changed respectively from 72o to 60o, from 60o to 45o, from 45o to 30o, and finally from 30o to 15o.

A general and rapid method for performance evaluation of enhanced heat transfer techniques

Evaluation of the comprehensive performance of different heat transfer technologies and selection the best enhanced surface to meet the requirements are of great significance for efficient energy recovery. In this paper, based on the previous research results from our group, a rapid multi-criterion comprehensive evaluation method of enhanced heat transfer surfaces was first proposed; it realizes the rapid evaluation of heat transfer performance under the condition of equal flow rate, equal pressure drop and equal pump power constraints. Three baselines divide evaluation plot into six zones, namely zone 1 (non-energy-saving zone), zone 2 (relative energy-saving zone), zone 3 (value-added energy-saving zone), zone 4 (ideal energy-saving zone), zone 5 (pure energy-saving zone), and zone 6 (simple energy-saving zone). A simplified evaluation plot was then developed to overcome the dependence on the correlations of the reference surface. Next, the prediction results of the evaluation plot under the condition of variable minimum flow cross-section area, variable total heat transfer area, variable equivalent diameter, and variable tube bundle arrangement were compared with the traditional method to verify the applicability and accuracy of the evaluation plot. Finally, numerical simulations and engineering application of typical heat transfer surfaces were conducted to compare the energy-saving effectiveness of different enhanced surfaces and to analyze the effect of geometry and operation parameters on comprehensive performance. The results showed that the evaluation chart established in this paper can be successfully applied to the comprehensive comparison of multiple evaluation criteria and has a high prediction accuracy. Compared with the common evaluation methods, this method has excellent practicability and visualization, and contributes to the rapid development of new enhanced surfaces and efficient utilization of energy.

Multi-Dimensional Performance Evaluation of Heat Exchanger Surface Enhancements

Enhanced heat transfer surfaces allow more energy-efficient, compact and lightweight heat exchangers. Within this study, a method for comparing different types of enhancement and different geometries with multiple objectives is developed in order to evaluate new and existing enhancement designs. The method’s objectives are defined as energy, volume, and mass efficiency of the enhancement. They are given in dimensional and non-dimensional form and include limitations due to thermal conductivity within the enhancement. The transformation to an explicit heat transfer rate per dissipated power, volume, or mass is described in detail. The objectives are visualized for different Reynolds numbers to locate beneficial operating conditions. The multi-objective problem is further on reduced to a single-objective problem by means of weighting factors. The implementation of these factors allows a straightforward performance evaluation based on a rough estimation of the energy, volume, and mass importance set by a decision maker.

Experimental study on single phase operation of microjet augmented heat exchanger with enhanced heat transfer surface

The article presents experimental investigations on a prototype heat exchanger. Presented research is focused on combined active and passive enhancement techniques of surface modification and microjet impingement. The results were compared to reference plate heat exchanger without microjet impingement.The Wilson plot method was applied to determine the heat transfer coefficients in the single phase operation. The heat exchanger was capable of exchanging 300 W of thermal energy at LMTD of 40 K. The obtained overall heat transfer rates reach 600 W/m2.Introducing knurled surface resulted in ∼10% increase heat transfer area, and similar enhancement in transferred heat in reference to plate heat exchanger geometry. Knurled surface decreased heat transfer in combination with a multi-jet impingement in comparison to a smooth surface. A possible explanation of that effect is that the flow in wall jet region is disrupted by the knurled surface and directed in the bulk of the fluid. Initiating mixing with colder fluid, thicker thermal boundary layer, and affecting local temperature distribution.

Heat transfer and pressure drop correlations for laminar flow in an in-line and staggered array of circular cylinders

Enhanced heat transfer surfaces based on cylindrically shaped pin fins with wire diameters in the range of 100 µm were analyzed. The design is based on a high pin length to diameter ratio in the range of 20–100. Correlations for thermal and fluid dynamic characteristics of these fine wire structures are not available in literature. An in-line and staggered arrangement of pins were simulated for a variety of operational and geometrical conditions with a two-dimensional computational thermal and fluid dynamics model. Correlations for Nusselt number and friction factor with respect to Reynolds number and geometry were derived thereby. Reynolds numbers based on the wire diameter are in the range of 3–60. The correlations for the Nusselt number and friction factor can predict 93% and 97% of the simulated data within ±10%.

Experimental investigation and comparative performance analysis of a compact finned-tube heat exchanger uniformly filled with a phase change material for thermal energy storage

In the present paper, a latent heat storage system using a heat-transfer enhancement technique has been built and tested. The potential of using a natural phase change material of Moroccan provenance for energy storage was studied by experimental analysis. The enhanced heat transfer surface of the compact finned-tube heat exchanger presents geometric complications. Therefore, a new method based on equivalent circular fin efficiency for the calculation of the effective heat transfer surface area was developed and applied to the system under study. In order to carry out the performance analysis for this innovative system, charging and discharging experiments were conducted for different heat transfer fluid flow rates. It was found that increasing the flow rate from 0.2 to 1 l/min divides melting time by 2.5 and solidification time by four. The average effectiveness was calculated for each flow rate and was proven to decrease during charging from 0.95 for a flow rate of 0.2 l/min to 0.63 for 1 l/min. Likewise, increasing flow rate from 0.2 to 1 l/min for discharging process decreases heat exchanger effectiveness from 0.99 to 0.7. The combination of the effectiveness-number of transfer units method with the procedure that was developed to compute the effective heat transfer area lead to derive an empirical correlation. This equation was used to compare the finned-tube compact storage system with other heat and cold storage units. The comparison showed that the present system displayed satisfactory results. The second use of the correlation was to design, through a case study, a heat storage system suitable for solar domestic hot water production in a residential building.

Comparison of Heat Exchanger Designs Using Vipertex 1eht Enhanced Heat Transfer Tubes

A numeric study was performed that compares the performance of heat exchangers using the Vipertex 1EHT enhanced heat transfer tubes 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 1EHT 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 1EHT tube predicted over performance when compared to a smooth tube design. Vipertex 1EHT tubes produced higher performance and more efficient designs.

Thermodynamic properties of Al2O3 nanolubricants: Part 1—Effects on the two-phase pressure drop

In vapor compression cycles, a small portion of the oil circulates with the refrigerant throughout the system components and penalizes the heat transfer as well as increases the pressure losses. Nanolubricants—lubricants with dispersed nanoparticles—are expected to provide enhancements in heat transfer. While solubility and miscibility of refrigerants in polyolester lubricant are well-established knowledge, there is a lack of information regarding if and how nanoparticles dispersed in the lubricant affect these two properties. This article presents the experimental data of solubility and miscibility of three types of Al2O3 nanolubricants with refrigerant R410A. The nanoparticles were dispersed in polyolester lubricant by using three different surfactants. The data identified optimum combinations to achieve stable and uniform dispersions. The associated viscosity was also measured. The viscosity was about 2.6 higher at 5°C. The nanolubricants had also lower refrigerant R410A solubility with respect to polyolester oil, and surfactants slightly affected the viscosity and solubility properties of the nanolubricants. Finally, this article presents data of pressure drop for two-phase flow boiling in a horizontal tube with internally enhanced heat transfer surfaces and discusses the effect of the nanoparticles on the pressure drop of the mixture. Nanolubricant did not increase the two-phase pressure drop with respect to polyolester lubricant, and at low and medium mass flux, the pressure drop of nanolubricant were lower than the corresponding two-phase pressure drop of refrigerant R410A and polyolester oil mixture. Two correlations from the literature predicted well the pressure drop data of the refrigerant R410A and polyolester oil mixture of the present work, while their accuracy for the nanolubricant mixture was slightly over ±20%.

Crystallization Fouling With Enhanced Heat Transfer Surfaces

The aim of this paper is to demonstrate that a simple stirred batch cell can be used to study the effects of surface shear stress (among other process parameters) on fouling from saturated calcium salt solutions. For otherwise identical operating conditions, the overall fouling rate on a smooth mild steel surface was found to be reduced either when fine wires were attached to it or when helical threads were incorporated into the surface, either in the form of a continuous helical groove or in the form of a raised helix. The raised helical surface was more effective in reducing fouling than the helical groove. The results confirm the general effect that fouling rates can be reduced by increasing the surface shear stress through surface enhancement. A simple mathematical model has been developed to take into account the dynamic change in bulk concentration as crystallization fouling occurs. In all cases, the overall fouling resistance increased asymptotically toward a constant value and could easily and accurately be described quantitatively by the new analytical model. The variations of shear stresses on the various surfaces were determined from computational fluid dynamics simulations using the commercial package Comsol 4.2.

The Role of Pinnae Flapping Motion on Elephant Metabolic Heat Dissipation

The oscillatory rotational motion of the elephant pinna is considered a key mechanism in metabolic heat dissipation. Limited experimental investigations have revealed that the flapping of the elephant's pinna is responsible for surface heat transfer enhancement. The objective of the present experimental and computational work is to investigate the physics of the flow induced by the pinna's motion and its effects on the heat transfer. This was accomplished by designing, fabricating and testing two full-size laboratory models of elephant pinnae: one rigid and one flexible, both instrumented with small size thermocouples for time-dependent surface temperature measurements. A constant heat flux is applied to both sides of each model which is rotated about a fixed edge with a frequency of 2 rad/s in an infinite domain at ambient conditions. Of interest is the study of the impact of the flexural strength of the model's material on surface heat transfer. Additional computer simulations of the flow and thermal fields revealed a hooked-shape vortex tube around the free edges of the flapping pinna. This result is confirmed by the flow visualization with smoke particles. Both experimental and computational results exhibit local surface temperature profiles characterized by a transient unsteady periodic variation followed by a steady periodic phase. Flow visualization indicated significant interaction between the vortical structures shed off the edge and the flexible model's boundary layer. It has been found that the cooling of the flexible model is enhanced by 30%.

Heat transfer evaluation of an enhanced heat transfer tube bundle

Demands to increase performance of modern heat exchange systems are constantly being made. Typical requirements include the removal of larger amounts of energy or the development of process units that occupy a smaller unit footprint. Vipertex™ 1EHT enhanced surfaces have been designed and produced through material surface modifications in order to create flow optimized heat transfer tubes which increase heat transfer with only a modest increase in the friction factor. Considerations in the development of the enhanced, three dimensional 1EHT enhanced heat transfer surfaces include: maximization of heat transfer; minimization of operating costs; and/or a minimization of the rate of surface fouling. This study details the performance of a horizontal oriented 1EHT enhanced surface tube bundle and compares heat transfer results to a horizontal bundle of smooth tubes for single phase and two phase conditions. Results for the 1EHT bundle show an increase in the overall heat transfer coefficient up to 200% when compared to the heat transfer performance of a smooth tube bundle using typical fluids (n-Pentane, p-Xylene and water); for midpoint shellside Reynolds number values in the range of 2010–20,400; with effective mean temperature difference (EMTD) values between 8.6 °C and 65.7 °C. More nucleation sites are produced on the 1EHT tube surface than on an equivalent length of unenhanced commercial tube. Results from this bundle study indicate that the 1EHT enhanced tube surface is well suited for applications where nucleate boiling is significant. Enhanced heat transfer tube bundles using the 1EHT tubes are capable of producing efficiency increases making 1EHT tubes an important alternative to be considered in the design of high efficiency processes. Vipertex 1EHT tube bundles recover more energy and provide an opportunity to advance the design of many heat transfer products.