Concentric Tube Heat Exchanger Research Articles

Heat recovery from hot water drainage: CFD simulation, energy efficiency and exergoeconomic analysis of concentric tube heat exchangers

This study investigates the performance and economic viability of a heat recovery concentric tube heat exchanger (HR-CTHE) integrated with water heating systems using either electricity or natural gas. The system recovers heat from hot water drainage to preheat cold water, thereby enhancing energy efficiency. Computational Fluid Dynamics (CFD) simulations are conducted, examining cold and hot water drain Reynolds numbers ranging from 1,000 to 20,000, hot water drain inlet temperatures from 303 K to 333 K, diameter ratios from 1.25 to 3, and inner diameters from 0.01 m to 0.05 m. Results indicate that at an inlet temperature of 333 K and a hot water Reynolds number of 20,000, the heat recovery rate reaches approximately 20,000 W, and the preheated cold water temperature can achieve 316 K. Exergetic efficiency is highest at 0.4392 for a diameter ratio of 1.25 and an inner diameter of 0.01 m. Economic evaluations using Net Present Value (NPV) and discounted payback period indicate that coupling HR-CTHE with electric heaters is more attractive, providing higher savings and quicker returns on investment compared to natural gas heaters. For instance, integrating HR-CTHE with electric water heaters yields a discounted payback period as short as 0.2 years. In contrast, for natural gas heaters, the payback period is around 2.2 years under similar conditions. The exergoeconomic analysis further demonstrates that natural gas heaters achieve cost-effectiveness only under high hot water Reynolds numbers and inlet temperatures, while electric heaters show significant benefits at moderate to high Reh. The study concludes with recommendations for optimizing HR-CTHE performance and cost-effectiveness, emphasizing higher hot water inlet temperatures, lower diameter ratios, and appropriate Reynolds numbers for both fluids.

Thermo-hydraulic performance of concentric tube heat exchangers with turbulent flow: Predictive correlations and iterative methods for pumping power and heat transfer

This research addresses the problem of predicting the thermo-hydraulic performance of concentric tube heat exchangers (CTHE) under turbulent flow conditions, a critical aspect in energy-efficient industrial systems such as HVAC, power generation, and chemical processing. Existing studies often lack accurate predictive methods for balancing heat transfer performance with pumping power requirements. To tackle this issue, novel correlations and an iterative Newton–Raphson method were developed for predicting pumping power and heat transfer rates. Three-dimensional CFD simulations of a water-to-water counter-flow CTHE were conducted, with Reynolds numbers ranging from 4000 to 8000 for both the hot and cold fluids. The simulations employed the Reynolds-Averaged Navier–Stokes (RANS) equations with the k−ω SST turbulence model. The results demonstrated that increasing the Reynolds number enhances both heat transfer rates and pumping power, with the cold fluid requiring consistently higher pumping power. New correlations were developed to predict pumping power, capturing the impact of both entry and fully developed flow regions. These correlations showed an average error of less than 2.33% when compared with the CFD data. The iterative Newton–Raphson method for predicting heat transfer rates demonstrated high accuracy, with an average error of 0.66% for heat transfer rate, 0.03% for hot fluid outlet temperature, and 0.01% for cold fluid outlet temperature. Additionally, we identified optimal operating conditions for efficient cooling and heating based on the heat capacity ratio (Cr). The novelty of this work lies in the development of new, highly accurate predictive correlations and iterative methods for optimizing CTHE performance, going beyond existing literature by providing comprehensive insights into the relationship between pumping power, heat transfer efficiency, and flow conditions.

Heat transfer and friction factor analysis for tomato puree flowing in a concentric-tube heat exchanger.

The heat and momentum transfer of tomato puree through a concentric-tube heat exchanger over a range of generalized Reynolds number (0.05<Re<66.5) was experimentally and numerically analyzed. Thermophysical and rheological properties of tomato puree (12°Brix) were measured from 20 to 60°C. The velocity, pressure, and temperature were calculated using the computational fluid dynamics (CFD) software FLUENTTM with temperature-dependent transport properties. The thermal operation of the concentric-tube exchanger was satisfactorily predicted using CFD, indicating accurate measurement of tomato puree properties with temperature variations. A concordance was found between the calculated Fanning friction factor and generalized Reynolds with the experimental correlation. A modified Sieder-Tate correlation was established, which allows properly expressing the Nusselt number as a function of the Peclet number. Simple correlations for the mechanical work and the heat transfer rate as a function of the volumetric flow rate were derived. The thermal efficiency was high at low puree flow rates but decreased with higher rates. However, at high flow rates, ceased its decline, instead showing a slight improvement. The analysis confirmed higher heat transfer rates in the concentric-tube heat exchanger compared to a plain tube at low puree flow rates. The results offer valuable insights for assessing diverse operational conditions in dairy, beverage, sauce, and concentrated food industries. Additionally, they also enhance the analysis and design of concentric-tube heat exchangers. PRACTICAL APPLICATION: The knowledge of the rheological and hydrodynamical behavior of fluids in concentric-tube heat exchangers allows to explore a set of different operating conditions to improve the yield and effectiveness on the system heating/cooling design.

A correlation for U-value for laminar and turbulent flows in concentric tube heat exchangers

This paper introduces a novel empirical correlation designed to predict the overall heat transfer coefficient (U) in concentric tube heat exchangers. The study utilizes a comprehensive dataset of 2700 data points from CFD simulations, examining the impact of critical variables including hot and cold fluid Reynolds numbers (Reh, Rec), Prandtl numbers (Prh, Prc), and heat exchanger dimensions (tube hydraulic diameter Dh, annular space hydraulic diameter Dc, and overall length L). The analysis incorporates a range of fluid combinations in the tube and annular sections – air–air, air–water, water-air, and water–water – across Reynolds number ranges from 1000 to 20000, covering both laminar and turbulent flow regimes. The correlation was developed using the Adam optimizer to minimize the Weighted Mean Squared Error (WMSE), achieving an impressive convergence to an average prediction error of 6.7% compared to actual U values. The model categorizes flow into four distinct categories, each corresponding to a combination of flow patterns in the tube and annular spaces regimes – Laminar–Laminar, Laminar–Turbulent, Turbulent–Laminar, and Turbulent–Turbulent – integrating both hydrodynamic and thermal entry effects to enhance prediction accuracy. Rigorous error analysis revealed a median error of 5.18%, substantially outperforming existing models. Notably, 10% of the predictions deviate by less than 1%, with 90th percentile errors staying below 15%. Parameters were finely tuned through extensive numerical simulations, ensuring accurate application of the correlation across diverse operational conditions. The study concludes by highlighting the model’s potential to significantly enhance the design and efficiency of heat exchangers and proposes future enhancements to further improve its predictive accuracy.

Numerical investigation on thermohydraulic and exergy performance enhancement for triplex concentric tube heat exchanger using MXene nanofluids

Numerical investigation on thermohydraulic and exergy performance enhancement for triplex concentric tube heat exchanger using MXene nanofluids

Experimental study of graphene-based nanofluid dispersions stability for efficient heat transmission within a concentric tube heat exchanger

This study undertook the experimental enhancement of dispersion stability in graphene-based nanofluids to boost the performance of concentric counterflow heat exchangers. Emphasis was placed on the characterization and preparation of graphene suspensions by evaluating their dispersion properties in various solvents: water, ethanol, acetone, and dimethylformamide (DMF). The graphene powder underwent comprehensive analysis using X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier-transform infrared spectroscopy (FTIR). Subsequently, graphene suspensions were prepared and uniformly mixed using both a magnetic stirrer and an ultrasonic vibrator. The investigation confirmed that solvent type significantly influences the stability and solubility of the suspensions. Solutions of reduced graphene oxide (rGO) in water, ethanol, and DMF exhibited remarkable long-term stability, contrasting with those in acetone. Water emerged as the superior solvent for developing the thermal transport fluid. The addition of graphene resulted in a conductivity increase of approximately 48.15% at φ = 0.5% concentration, while the best thermal efficiency was attained at φ = 0.35% and a flow rate of 3 L/min. Furthermore, at lower flow rates, it is advisable to avoid higher concentrations to maintain optimal thermal efficiency.

Numerical investigation on assessing the influence of diverse-shaped hybrid nanofluids on thermal performance of triple tube heat exchanger

The present study explored the effects of hybrid nanofluids, composed of water-based nanoparticles in various shapes (MWCNT-cylindrical, Al2O3-blade, Graphene-platelet, and Fe3O4-brick), within a triple concentric tube heat exchanger (TCTHX). Theoretical and computational modeling was conducted for the flow of hot water and hybrid nanofluids at varying inner annulus mass flow rates (0.1 kg/s to 0.5 kg/s and at a fixed temperature of 70 °C) in the TCTHX; their influence was analyzed by the energetic and exergetic performance and revealing the findings to enhance the heat transfer efficiency.The key finding of the work is that the thermal performance factor (TPF) of the brick-blade hybrid nanofluid in the TCTHX is 4.26, which is the maximum as compared to brick-platelet, brick-cylindrical, blade-platelet, blade-cylindrical, and platelet-cylindrical hybrid nanofluids for all mass flow rates. The brick-blade hybrid nanofluid is the most economical in the TCTHX system, followed by the brick-cylindrical hybrid nanofluid. Overall, the combination of brick-blade hybrid nanofluid performs best in the TCTHX system in terms of performance index, TPF, and CBR. Brick-platelet hybrid nanofluid is 7.20% less efficient than water at a mass flow rate of 0.1 kg/s. Platelet-cylindrical hybrid nanofluid exhibits 12.71% and 5.09% lower heat transfer rate and performance index than delaminated (DI) water at the lowest mass flow rate in the TCTHX system. Brick-platelet hybrid nanofluids show a reduced Nusselt number ratio for the tested mass flow rates. Entropy generation in blade-platelet hybrid nanofluid is 19.49% lower than in (DI) water.

An Experimental Investigation of the Effects of Using Hexagonal BN–Water Nanofluids on the Thermal Performance and Pressure Drop of a Concentric Tube Heat Exchanger

The thermal conductivity of recently produced hexagonal boron nitride (hBN)-containing nanofluids is comparatively higher than their viscosity, indicating that these materials belong to a relatively novel class. In this study, hBN–water nanofluids in stable and dispersed concentrations were used in parallel and counterflow experiments at volumes of 0.01%, 0.1%, and 1%, as well as at various flow rates and Reynolds numbers. When employing hBN–water nanofluid in a counter-flow heat exchanger instead of distilled water, the results showed a 16.7% increase in the overall heat transfer coefficient. The findings also showed that, in comparison to a counter-flow heat exchanger, employing hBN nanofluid as the cold fluid in a parallel-flow heat exchanger produced superior results in terms of an increase in heat transfer. The effects of nanofluid concentration on pressure drops were investigated through experiments conducted in both parallel- and counter-flow conditions.

Numerical Investigation on Flow and Heat Transfer characteristics of Pure Water in Concentric Triple Tube Heat Exchanger

In the current study, the investigation of heat transfer and fluid flow Characteristics of Pure water when pass through a triple tube heat exchanger (CTTHX). this investigation has been conducted across various Reynolds Number to gain insights into their performance also conducted a computational fluid dynamics (CFD) simulation using the ANSYS-FLUENT software. Result obtained was validated by comparing to empirical correlation data found in the existing literature. The investigation considered various operating variable as Reynolds Number and temperature across the inner, intermediate, and outer tubes. Specifically, the Reynolds Number of 2000 at 305 K, a range of 2000 to 4500 at 340 K, and 2000 at 295 K for the respective tubes. Key findings are that friction factor increase by 12.5% as compared to correlation in existing literature. And Nusselt number (Nu) increase by 50% in the range of Reynolds Number (Re) from 2000 to 4500.

CFD Simulation of Triangular Shape and Circular Shape Concentric Triple Tube Heat Exchanger

In the current study, the investigation of heat transfer and fluid flow Characteristics of Pure water when pass through an inner annulus triangular shape and circular shape triple tube heat exchanger (CTTHX). this investigation has been conducted across various Reynolds Number to gain insights into their performance also conducted a computational fluid dynamics (CFD) simulation using the ANSYS-FLUENT software. Result obtained was validated by comparing to empirical correlation data found in the existing literature. The investigation considered various operating variable as Reynolds Number and temperature across the inner, intermediate, and outer tubes. Specifically, the Reynolds Number of 2000 at 305 K, a range of 2000 to 4500 at 340 K, and 2000 at 295 K for the respective tubes. Key findings are that friction factor of triangular shape is increase by 10.5% and for circular shape by 2.69% as compared to correlation in existing literature. And Nusselt number (Nu) for triangular shape increase by 39.19% and for circular shape by 13.30% as compared to correlation in the range of Reynolds Number (Re) from 2000 to 4500. The effectiveness was increased by 16.67% and 7.6% for triangular shape and circular shape respectively as compared to existing literature.

Numerical Analysis of the Unsteady Mixed Convection of a Nanofluid in a Concentric Tube Heat Exchanger

In the present work, a numerical investigation of the unsteady mixed convection and entropy generation of a nanofluid in an annular cylindrical space is presented using the Buongiorno’s two-phase flow model. It deals with a concentric tube heat exchanger where the inner cylinder rotates with a constant frequency and is maintained at hot temperature, while the outer cylinder is cold. The aim of the present investigation is to highlight the effects of some parameters on the hydrodynamic, thermal and mass behavior of the considered nanofluid as well as on the system irreversibility, namely: the inertia (1 ⩽ Re ⩽ 20), the buoyancy (0 ⩽ Ri ⩽ 5), the mass diffusion (0.1 ⩽ Le ⩽ 10) and the vertical positions of the inner cylinder (-0.4 ⩽ H ⩽ 0.4). Moreover, at specific parameters, an optimal position in terms of heat transfer has been determined. The flow of the nanofluid is two-dimensional and governed by the equations of continuity, momentum, energy as well as volume fraction conservation. After performing a finite element method mesh test and validation with the literature, the Nusselt number and the entropy generation are discussed. The results show that the heat transfer rate and entropy generation increase with increasing values of Richardson and Reynolds number, especially when positioning the inner cylinder in the lower part. On the other hand, the nanoparticles migration under the thermophoretic diffusion decrease with the increase of the Lewis number, which consequent decrease of the heat transfer rate.

The evaluation of the performance of the heat exchanger of a triple concentric tube configuration with ionic liquid (imidazolium) and MWCNT ionanofluid

In this study, a triple concentric tube heat exchanger (TCTHE) was designed. It had three copper concentric tubes. Their thicknesses were 0.762 mm, 1.143 mm, and 1.27 mm. The diameters were 9.525 mm, 22.25 mm, and 34.925 mm, respectively. The tube’s length was 670 mm. The cooling medium used was the ionic-liquid (IL) 1-Ethyl-3-methylimidazoliumtetra-flouraborate [EMIM][BF4] and the ionanofluid (INF) prepared of 0.5% Multi walled carbon nanotubes (MWCNT) in [EMIM][BF4], while oil forty stock was the hot fluid, to investigate TCTHE performance. The volumetric flow rate (VFR) of the cooling medium was 20-55 l/hr, with a 25-27 °C temperature (temp). VFR of the hot fluid was constant and equal 20 l/hr. The inlet oil temp was 50, 60, and 70 oC, respectively. The type of flow was countercurrent. The heat transfer was investigated by calculating different parameters for the cooling medium. There was an improvement in the Nusselt number (NU) of INF of 5% compared to the IL. A 75% increase in the friction factor of INF was found compared to that of IL. A 95% increase in the pressure drop was calculated in the inner tube using INF compared with that of IL. The overall heat transfer coefficient (U) was enhanced by 3% using INF in comparison with IL. Fi-nally, U showed some improvement, resulting in increased heat transfer. In conclusion, using the prepared INF lead to improve the heat transfer in the TCTHE.

Advances in triple tube heat exchangers regarding heat transfer characteristics of single and two-phase flows in comparison to double tube heat exchangers part 1

Abstract Triple concentric-tube heat exchangers are used widely in refrigeration, drying, energy storage, chemical systems, and the food industry. To handle excessive temperature differences, the heat transfer area, as an option, the heat exchanger’s length, is necessary to be increased. Triple tubes have a significant advantage in this regard in comparison to double ones. The target of this review is to discuss the most recent publications, including the single-phase flows in these heat exchangers, focusing on the heat transfer and hydrodynamic characteristics, and to classify them with various contemporary aspects. The operating conditions, enhanced surfaces, and sizes, as well as the geometrical parameters, are categorized as being part of experimental, numerical, and analytical research. The studies indicate that the heat transfer characteristics of triple concentric-tube heat exchangers are better than those of double tube heat exchangers. In single-phase studies, the convective and overall heat transfer coefficients, Nusselt number, heat transfer rate, and effectiveness are greater in triple heat exchangers than in double heat exchangers, and the heat exchanger length required to achieve the same heat transfer performance is shorter in triple heat exchangers than in double heat exchangers. Heat transfer surface area increases by adding a concentric third tube. Advanced surfaces enhance heat transfer compared to smooth surfaces and flow turbulence in comparison to smooth surfaces. Heat transfer from triple-one enhanced surfaces is not well-analyzed. Design and use of triple ones as a double one’s alternative should advance shortly.

Advances in triple tube heat exchangers regarding heat transfer characteristics of single and two-phase flows in comparison to double tube heat exchangers part 2

Abstract Triple concentric-tube heat exchangers are often used in a variety of industries, including HVAC, food and beverage manufacturing, and chemical processing. They may also be utilized in applications requiring thermal homogeneity, such as food and pharmaceutical production. They are appropriate for a number of applications since they may be constructed to withstand a range of temperatures and pressures. The purpose of this study is to examine the most current papers, covering single- and two-phase flows having pure and nanofluids with a particular emphasis on the heat transfer and hydrodynamic properties. The use of advanced surfaces improves heat transfer with respect to smooth surfaces, and the use of nanofluids has a positive influence on heat transfer characteristics with the increase in nanoparticle volume concentration since nanoparticles rise thermal conductivity, heat transfer area, and Brownian motion. The practical calculation methodologies, proposed correlations for calculating the Nusselt number and friction factor in triple ones are shown. There are insufficient studies to comment on pressure drop features, and correlations for Nusselt numbers and friction factors that are only known for single-phase flows. The research indicates that the heat transfer characteristics of triple concentric-tube heat exchangers surpass those of double tube heat exchangers. Important progress is supposed to occur for the design and utilization of triple ones as a substitute for double ones soon. Finally, there are a limited number of experimental two-phase flow studies in triple ones. It is essential to work on this topic to meet the important lack in open sources.

Innovative algorithmic approach of determining the overall heat transfer coefficient of concentric tube heat exchangers

Heat exchanger analysis is regarded to be challenging due to the numerous parameters influencing the overall heat transfer coefficient. Errors in estimating convective heat transfer coefficients often arise from the geometric complexity of heat exchangers and varying flow regimes. The current work proposes a novel iterative method for calculating the overall heat transfer coefficients of concentric tube heat exchangers based on the Reynolds number of the two fluid streams. The approach is validated using numerical simulations performed with ANSYS-FLUENT, focusing on Reynolds numbers ranging from 4000 to 8000 for both hot and cold streams. The proposed method yields a maximum percentage of error between the CFD results and the correlation of just 1.2% for all Reynolds number combinations studied. The mean squared error (MSE) decreases by approximately 9% when 25 data points are used for the correlation fitting process compared to using only 5 data points. A comparison with existing literature correlations reveals a strong agreement within ±5% difference, demonstrating the accuracy and reliability of the developed correlation in predicting the overall heat transfer coefficients in concentric tube heat exchangers over the investigated range of Reynolds numbers.

Morphing optimization of flow and heat transfer in concentric tube heat exchangers

Concentric tube heat exchangers are vital in various industrial applications, including chemical, process, energy, mechanical, and aeronautical engineering. Advancements in heat transfer efficiency present a significant challenge in contemporary research and development. This study concerns optimizing flow and heat transfer in concentric tube heat exchangers by morphing the tube's walls. The adjoint shape optimization approach is implemented in a fully turbulent flow regime. The effect of inner tube deformation on flow physics and heat transfer is examined. The results show that morphing can lead to a 54% increase in the heat transfer rate and a 47% improvement in the overall heat transfer coefficient compared to straight concentric tube designs. Moreover, the thermal-hydraulic performance factor is calculated to account for the relative increase in heat transfer when the optimal and initial designs are operated under the same pumping power. A thermal-hydraulic performance factor of 1.2 is obtained for the new design, showing that the heat transfer enhancement caused by morphing the tube's walls outweighs the increase in pumping power. The physics of a radial flow, resulting from an adverse pressure gradient in an annular region caused by the successive inner tube deformation, significantly augments heat transfer. This study shows morphing can lead to higher thermal efficiencies, and numerical optimization can assist in achieving this goal.

Experimental and numerical analysis of heat transfer enhancement inside concentric counter flow tube heat exchanger using different nanofluids

The aim of this paper is to study experimentally and numerically heat transfer enhancement and friction factor inside a counter flow concentric tube heat exchanger using different volume fractions of CuO, Al2O3, and TiO2 nanofluids. Using nanofluids increases the thermal conductivity and conductive heat transfer coefficients compared to the base fluids. Increased heat transfer coefficients reduce the required tube length leading to reduced pressure drop in heat exchangers. Nanofluids have a high specific surface area, and therefore more heat transfer surface between particles and fluids is available. A standard k-ε turbulence model based on two equations was used in this investigation to solve the momentum and energy equations of nanofluids. The results were presented for Reynolds number range between 2000 and 12,000 and two different volume fractions of 0.05 and 0.2%, respectively. The numerical results illustrated that all the tested nanofluids exhibited better heat transfer coefficients compared with pure water. Particularly, CuO nanofluid illustrated the highest performance index for both concentrations. The performance index varied from 4.25, 3, and 2.5 to 1.5 for CuO, Al2O3, and TiO2 nanofluids, respectively, for the whole range of Reynold numbers. The results of this investigation may be used in designing heat exchangers-based nanofluids that can be used in many energy applications such as solar, energy production systems, and any industrial process.

Thermoeconomic and environmental impacts of vortex generator-equipped multi-drain heat recovery systems under various renewable sources

In response to escalating energy demands, intensifying climate change concerns, and growing environmental degradation, the incorporation of renewable energy sources has gained traction across diverse sectors and regions. Concomitantly, scientists and engineers have recognized the potential of heat recovery systems in mitigating energy consumption, fostering further investigations into their practical applications. This study introduces an innovative design, integrating vortex generators into a concentric tube heat exchanger for heat recovery from a multi-drain water system that serves 48 accommodations. The design's sustainability is assessed by evaluating its economic, and environmental implications when paired with various renewable energy sources. Specifically, the aim is to quantify both cost and environmental savings engendered by implementing this design in a multi-drain application for a building with 48 accommodations.A numerical investigation elucidates the effects of flow rate variations on heat transfer, overall heat transfer, and thermal enhancement factors. Four types of renewable energy input - solar, wind, biomass, and hydropower - along with one storage system (pumped storage) are analyzed. The study reveals that the design implementation results in an elevation of cold water temperature between 3.5 and 7.5 °C. Furthermore, daily environmental savings for solar, wind, biomass, hydropower, and pumped storage are estimated to be 0.783 €, 0.339 €, 0.141 €, 0.027 €, and 1.356 €, respectively. Conversely, daily economic savings are calculated to be 3.62 €, 2.49 €, 5.05 €, 3.62 €, and 6.70 € for each corresponding energy source. This research underscores the viability of the proposed design in fostering sustainability through both environmental preservation and economic efficiency.

Power generation of annular thermoelectric generator with silicone polymer thermal conductive oil applied in automotive waste heat recovery

The annular thermoelectric generator (ATEG) matches the shape of the exhaust pipe. To improve the power generation efficiency of the ATEG in automobiles, a scheme is proposed to use a silicone polymer-based thermal conductive oil to transfer heat from the exhaust. Based on this concept, a new type of concentric tube heat exchanger is designed. A finite element model of the new system is established by considering temperature gradients, temperature dependence, and fluid resistance characteristics. Numerical simulations are performed to investigate the effects of exhaust parameters, thermal oil parameters, and heat exchanger structure on thermoelectric performance. The findings demonstrate a 15.2% increase in maximum output power of the new generator compared to a conventional ATEG, accompanied by a 19% decrease in the optimal thermoelectric module area. Furthermore, the net power first increases and then decreases with increasing thermal oil mass flow rate. The thermal oil mass flow rate can be adjusted in real-time based on fluctuations in exhaust parameters to achieve peak net output power. Finally, optimal fitting relationships between the heat exchanger dimensionless diameter and the total diameter, as well as between exhaust parameters and the optimal thermal oil mass flow rate, are obtained through parameter analysis and derivation.

Experimental Analysis of GO-Al2O3/Water Nanofluid in A Concentric Tube Heat Exchanger

Isı değiştiricileri, ısıtma ve soğutma sistemleri gibi birçok endüstriyel uygulamada sıklıkla kullanılmaktadır. Isı değiştiricilerin ısıl performanslarının arttırılması için, çalışma akışkanının termofiziksel özelliklerini iyileştirecek nano boyutlu parçacıklar eklenmesi iyi bir çözüm olabilir. Bunun yanında, son yıllarda hibrit nanoakışkanlar olarak bilinen iki veya daha fazla farklı nanopartikül kullanılarak elde edilen nanoakışkanların ısıl performanslarında daha yüksek iyileştirme elde edildiği görülmektedir. Bu deneysel çalışmada grafen oksit (GO) – alüminyum oksit (Al2O3)/su hibrit nanoakışkanı GO-Al2O3 /su hibrit nanoakışkan kullanılarak, borulu bir ısı değiştiricisinin termal veriminin arttırılması amaçlanmıştır. Bu kapsamda GO-Al2O3 /su hibrit nanoakışkanı, ısı değiştiricide iki farklı modda (paralel ve karşıt) olarak denenmiş ve sonuçlar karşılaştırılmıştır. Kullanılan GO-Al2O3 /su hibrit nanoakışkanının konsantrasyon oranı %1 olarak seçilmiştir. Bu çalışmanın deneysel sonuçları, ısı değiştiricide GO-Al2O3 /su hibrit nanoakışkanının kullanılmasının ısıl performansı önemli ölçüde iyileştirdiğini göstermiştir. GO-Al2O3 /su hibrit nanoakışkanının %1 konsantrasyon oranında kullanıldığı sistemde toplam ısı transfer katsayısında paralel ve karşıt akışlı durumda sırasıyla %9.8 ve %10.7 artış değerleri kaydedilmiştir.