Concentric Tube Heat Exchanger Research Articles

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 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.

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.

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.

On design and analysis of a concentric tube micro fin heat exchanger for applications of tire pyrolysis lube oil cooling

Concentric tube heat exchangers are widely used as lube oil coolers in large internal combustion engines. They are particularly preferred because of simple manufacturing, lower area, and better heat transfer characteristics. With the growing use of unconventional fuel-based lubricants, their design is continuously improved to achieve the required heat transfer characteristics. One of the emerging alternative oil is Tire Pyrolysis Oil (TPO) to minimize tire waste and achieve the waste-to-energy objective. The TPO is employed not only as diesel blended fuel but also as a lube oil because of its satisfactory tribological properties. The present work provides a detailed design and analysis of a concentric-tube micro-fin-based lube oil cooler for TPO applications. The design encompasses the thermal, hydraulic, and economic characteristics of the heat exchanger subjected to TPO, Ethylene Glycol (EG), and Crude Oil (CO). To achieve this a robust numerical model is developed and implemented using engineering equation solver software. The model is validated with experimental data first. Then a detailed parametric analysis is done to investigate the heat exchanger performance. It was observed that TPO offered a better heat transfer coefficient along with lesser power input and cost compared to EG and CO. For instance, in the case of a mass flow rate 0.1 kg/s, the heat transfer per unit pressure drop is highest for TPO with 5.86 m/sK followed by CO with 5.12 m/sK and EG with 0.3876 m/sK. Similarly, the annual operational cost is calculated as 27.7 k$, 31.4 k$, and ∼ 80.8 k$ for the TPO, CO, EG which shows the superiority of TPO as lube oil for engine applications. Based on thermal, hydraulic design and economic analysis, it is concluded that tire pyrolysis oil (TPO) is used in the concentric tube micro fin heat exchanger for applications of oil cooling.

Adaptive observer design for uncertain hyperbolic PDEs coupled with uncertain LTV ODEs; Application to refrigeration systems

The problem of estimating the temperatures and the heat transfer coefficient of a concentric tube heat exchanger coupled with a heater is considered in this work. Measurements collected from the extremities of the exchanger tube are used to estimate the heat distribution over the length of the exchanger, which induces a boundary estimation problem. This system, which is part of any standard cooling plant, is particularly challenging due to the distributed nature of its variables. It is modeled by a system of (2 × 2) hyperbolic PDEs, coupled with an ODE at the boundary. To solve the estimation problem, we consider a general class of systems consisting of a (2 × 2) hyperbolic system coupled with a set of nX linear time-varying (LTV) ODEs at the boundary. Both the PDE and the ODEs have uncertain parameters to be estimated. The objective is to estimate the PDE states, the ODE states, and the parameters simultaneously with no assumption on the ODEs stability. We design a Luenberger state observer, and our method is mainly based on the decoupling of the PDE estimation error states from that of the ODEs via swapping design. We then derive the observer gains from the Lyapunov analysis of the decoupled system after proving the boundedness of the swapping filters. We give sufficient conditions of the exponential convergence of the adaptive observer through differential Lyapunov inequalities (DLIs). Finally, we apply the developed theory on the coupled heat exchanger–heater model to evaluate the performance of the observer in numerical simulations.

Numerical investigations on a triple fluid heat exchanger with helical and sinusoidal coils

A modification is made in the existing concentric heat exchanger design to enhance its heat duty. A standard concentric tube heat exchanger is modified by considering two inner tubes with a combination of helical and sinusoidal coils. Numerical studies are performed in this triple fluid heat exchanger to assess its thermal performance by taking into account mass flow rate, fluid temperatures, heat transfer, which are governed by fundamental heat transfer equations. Computational fluid dynamics simulation methodology together with local and element-by-element method is applied with a MatLab computer code. Hot water and milk fluids are used as working fluids in helical and sinusoidal coils, respectively. Cooling water is used as shell side fluid. The attainment of high heat-load-per-unit-area and high surface-area-to-volume ratio is used as optimizing parameter in the simulations. The helical coil provides an increase in heat transfer rate and overall heat transfer coefficient increases by a percentage 13% for varying hot fluid flow rates, when it is compared with the sinusoidal coil. The pressure drop for the helical coil increases, exponentially compared to the sinusoidal coil, thereby it shows a higher pumping power for the helical coil.

Experimental Investigation of the Effect of Integrated Fins on Heat Transfer Rate of Double Pipe Heat Exchanger

In this paper, the effects of integrated fins on the thermal performance of the concentric tube heat exchanger with a variable flow rate of hot and cold water are discussed. The inner pipe is made of copper pipe of length = 800 mm, OD=30 mm, ID=26 mm, t=2 mm. the integrated fines of the geometry 1.25 mm and 1.5 mm pitch length, 1 mm of the depth of cut are considered in the study. The thermal performance of the heat exchanger with a flow rate of hot and cold fluids ranges from 0.014 kg s- 1 to 0.07 kg s-1 and the effects of parallel and counter flow direction are also discussed in detail. The experimental result confirms that the thermal performance of the concentric tube heat exchanger is more in the case of the tube with integrated fins and counter flow direction with the highest flow rate of water in the pipe and annulus of the heat exchanger.

Performance Evaluation of a Triple Concentric Tube Heat Exchanger Using Deionized Water and Oil-40

This study examines experimentally the performance of a horizontal triple concentric tube heat exchanger TCTHE made of copper metal using water as cooling fluid and oil-40 as hot fluid. Hot fluid enters the inner annular tube of the TCTHE in a direction at a temperature of 50, 60 and 70 oC and a flow rate of 20 l/hr. On the other hand, the cooling fluid enters the inner tube and the outer annular tube in the reverse direction (counter current flow) at a temperature of 25 oC and flow rates of 10, 15, 20, 25, 30 and 35 l/hr. The TCTHE is composed of three copper tubes with outer diameters of 34.925 mm, 22.25 mm, and 9.525 mm, and thicknesses of 1.27 mm, 1.143 mm, and 0.762 mm, respectively. TCTHE tube's length was 670 mm. Nusselt number, overall heat transfer coefficient, convective heat transfer coefficient (CHTC), friction factor and pressure drop were measured from the obtained experimental results and plotted in graphs against Reynold number and volumetric flow rate of water. These parameters appeared good results in the cooling process. Nusselt numbers increased linearly with DIW flow rate for both C1 and C2 reaching maximum values of 38.25 and 14.64 respectively. CHTC increased linearly with the DIW flow rate for both C1 and C2 reaching maximum values of 2934.3 and 871.7 respectively. Overall heat transfer coefficient of DIW reached maximum values of 296.36 and 251.4 at 35 l/hr for C1 and C2, respectively. Friction factor DIW in C1 and C2 decreased with the volumetric flow rate increases, reaching minimum values of 0.04 and 0.25 respectively. Pressure drop of DIW increased linearly with flow rate reaching maximum values of 81.4 and 4.31 for C1 and C2 respectively. This in turn leads to reduced TCTHE length and size leading to a decrease in the construction cost of the heat exchanger.