Concentric Tube Heat Exchanger Research Articles

Analysis of Shell and Double Concentric Tube Heat Exchanger Using CFD Application

This study focuses on CFD analysis in the field of the shell and double concentric tube heat exchanger. A commercial CFD package was used to resolve the flow and temperature fields inside the shell and tubes of the heat exchanger used. Simulations by CFD are performed for the single shell and double concentric tube.
 This heat exchanger included 16 tubes and 20 baffles. The shell had a length of 1.18 m and its diameter was 220 mm. Solid Works 2014, ANSYS 15.0 software was used to analyze the fields of flow and temperature inside the shell and the tubes. The RNG k-ε model was used and it provided good results. Coarse and fine meshes were investigated, showing that aspect ratio has no significant effect. 14 million elements were used in the mesh. A comparison was made between the profiles of temperature and velocity for the experimental and results of the model and it had an acceptable adaptation.

Analysis on thermal and flow behavior of triple concentric tube heat exchanger handling MWCNT-water nanofluids

Design of heat exchangers and heat transfer enhancement methods are struggling to meet out the cooling demand of present scenario. Many researchers suggested that the addition of nanosized solids particles into traditional base fluids resulting the higher heat transfer rate than the existing coolants and named the new fluids as nanofluids. In this investigation, the effect of microwave carbon nanotube (MWCNT)-water nanofluids on heat transfer rate, pressure drop and pumping power of a triple concentric tube heat exchanger are experimentally investigated and compared the results of MWCNT-water nanofluids with water. The MWCNT-water nanofluids were prepared by two step method at the volume concentrations of 0.2%, 0.4%, and 0.6%. The range of target fluid mass-flow rate is in the range of 0.026 to 0.039 kg per second and the constant heat flux condition is considered. On experimentation, it is noted that the effectiveness and presure drop of 0.6% MWCNT-water based nanofluids are 27% and 21% greater than water at the maximum mass-flow rate. The reason for improved heat transfer rate of nanofluids is because of higher thermal conductivity, Brownian motion, lower boundary-layer thickness, and lower specific heat capacity of nanofluids. Also found that the pumping power increases with increasing volume concentration and pumping power is 25% higher than water at the 0.6% nanofluids. Therefore, the MWCNT-water nanofluids are good choice for replacing water as coolant in triple concentric tube heat exchanger.

Multi-Objective Optimization of a Concentric Tube Heat Exchanger for Waste Heat Recovery in a Natural Gas Turbocharged Engine

Climate change and the growing demand for fossil fuels have encouraged researchers to provide more efficient engineering solutions for waste heat recovery in the industrial sector. The heat transfer between the exhaust gas and the thermal oil fluid in the concentric tube heat exchanger implies heat transfer irreversibility and high investment costs, which have been considered as objective functions to be minimized in this study. Therefore, the main objective of this article is to present the multi-objective optimization results applied to a concentric tube heat exchanger integrated to a GE Jenbacher turbocharged engine type 6, in which genetic algorithms are used to generate multiple solutions to the problem, choosing the best option through the Multiple-criteria decision technique known as TOPSIS. The CAD of the device has been recreated using the SolidWorks software, and the computational fluid dynamics (CFD) model has been made with the open-source tool OpenFOAM. The geometric configuration selected allows energy recovery, with a purchase equipment cost, and its entropy generation number (NGE), using Therminol-75 as thermal oil to exchange heat with the engine exhaust gases. This type of result provides the insertion of this equipment to the industrial sector because of the increase in the overall thermal efficiency of the natural gas engine.

Consequence of nanoparticle physiognomies on heat transfer characteristics of heat exchanger

ABSTRACT In this paper, the heat transfer coefficient and the heat transfer rate of a heat exchanger is evaluated by using nanofluids. The silicon carbide nanoparticles, milled and sonificated as nanofluids with volume fractions of 0.01499(%) and 0.01399(%) are used. The heat transfer characteristics of SiC(P)/water, SiC(M)/water, SiC(P)/EG, and SiC(M)/EG are measured in a concentric tube heat exchanger under laminar flow condition. The consequence of nanoparticle physiognomies and Reynolds number, on the heat transfer characteristics are evaluated. It has been found that the addition of milled nanoparticle in the base fluids enhances the heat transfer characteristics rather than the normal nanoparticle. The experimental results shows that the heat transfer coefficient rate of SiC(M) is higher than that of SiC(P) in both the case of water and EG. Further the Reynolds number and Nusselt number for SiC (M) was found higher than SiC (P), which is essential for heat transfer flow.

Heat transfer based flowmeter for high temperature flow rate measurements: Design, implementation and testing

The present work deals with the design, implementation and testing of a new heat transfer-based flowmeter. The suggested flowmeter allows the measurement of flow rates in applications involving hot fluid flows, mainly gas flows. The suggested flowmeter operates by circulating a cold fluid (water) of a known flow rate and temperature in a concentric tube heat exchanger in an opposite direction to the main flow of hot fluid of unknown flow rate. The flowmeter enables, from temperature measurements and the energy balance of the exchanger, the determination of the unknown flow rate. It was shown that the suggested flowmeter can reach accuracies greater than 90% depending on different parameters. The flowmeter's precision was shown to be increased with the increase of both cold and hot flow rates. The suggested flowmeter can be enhanced when the fluid temperatures are within the optimal range of operation which are achieved and specified by the design parameters.

Heat Transfer Enhancement of a Concentric Tube Heat Exchanger with Circumferential Circular Staggered Fins

Heat Transfer Enhancement of a Concentric Tube Heat Exchanger with Circumferential Circular Staggered Fins

Thermal Analysis and Performance Evaluation of Triple Concentric Tube Heat Exchanger

Triple concentric-tube exchanger (TCTHE) is an improved version of double concentric tube heat exchanger (DCTHE). Introducing an intermediate tube to a DCTHE provides TCTHE and enhances the heat transfer performance. Recognizing the need of experimental results, extremely scarce in the literature and essential to validate theoretical analyses, the aim of this work is to investigate thermal behavior of TCTHE. The present study includes design, development and experimental analysis of TCTHE for oil (ISO VG 22) cooling application required for industrial purposes. It comprises of water (cooling fluid) flowing through innermost tube as well as outer annulus and oil (hot fluid) flows through inner annulus. The experimental studies of the temperature distribution for three fluids along the length and heat transfer characteristics for TCTHE under insulated condition for counter current flow mode are carried out and discussed. The effect of change in oil (hot fluid) temperatures is analyzed keeping water inlet temperatures same at various operating conditions. The experiments have been conducted by varying flow rate of one of the fluids at a time and keeping other two fluid flow rates constant. The results are expressed in terms of temperature variation for all three fluids along the length. The effect of change in hot fluid inlet temperature is expressed in terms of heat transfer rate variation with respect to Reynolds number. The variation of non-dimensional parameters as temperature effectiveness and thermal conductance with respect to Reynolds number is also presented in this paper. Theoretical studies are carried out for evaluation of heat transfer rate using empirical correlations. Experimental validation is carried out for degree of cooling at different Reynolds numbers with theoretical analysis.

Heat transfer augmentation of internal flow using twisted tape insert in turbulent flow

Heat transfer augmentation of turbulent single-phase flow in a concentric tube heat exchanger with short-length twisted tape inserts was numerically examined herein. The twisted tape length ratios were 0.25, 0.5, 0.75, and 1.0. The twisted tape was comprised of an aluminum strip with a constant thickness, a pitch, and a width of 0.7, 35, and 12.6 mm, respectively. This study was conducted for heat exchangers with/without twisted tape inserts. The Reynolds numbers ranging from 4,500 to 18,500 were applied. The analyses showed an improvement in heat transfer and friction factor in each of the tube systems, and the results were used to determine the system that delivered the best performance. The correlations of Gnielinski and Petukhov were also used for validating the predicted Nusselt number and friction factor for the plain tube. The results indicated that heat transfer augmentation was elevated as the tape-length ratio increased. The respective highest average Nusselt number and friction factor obtained in this study were 0.51 and 2.84 times greater than that of the plain tube.

Experimental study on Al2O3 /H2O nanofluid with conical sectional insert in concentric tube heat exchanger

ABSTRACT A parallel flow heat exchanger containing conical sectional inserts with three different pitch ratio (i.e., 1, 2, and 3) in a different orientation to the flow direction of the working fluid had been fabricated. Al2O3 with different volume concentration, i.e., 0%, 2%, and 4% nanoparticles (90 nm size) were added to De-ionized water as the working fluid. The combined effect of the Nanofluid and the inserts in different orientations was studied. It was concluded that the insert, flow direction, and Nanofluid volume concentration provided most augmented heat transfer and enhanced the thermal properties.

Effective Overall Heat Transfer Coefficient Solver in a Triple Concentric-Tube Heat Exchanger

A relation for calculation of the effective overall heat transfer coefficient in a triple concentric-tube heat exchanger is proposed. The relation of the effective overall heat transfer coefficient is obtained based on total thermal resistance and it is applied within a case study for thermal analysis of two triple concentric-tube heat exchangers with different geometries, hot fluids and operating conditions. Through case study it is found that the values of effective overall heat transfer coefficient can be obtained with acceptable errors, up to 3 % for both heat exchangers.

Design of a heat exchanger of three concentric tube layer on contrary flow

Heat exchangers is a device that produces heat transfer from one fluid to another fluid. This study was conducted to design and build triple concentric tube heat exchangers with counterflow which is used to reduce the temperature of the hot fluid. The hot fluid flows in the annulus section on the second copper tube, then the cold fluid each flows through the first copper tube and annulus portion to the third copper tube. The hot fluid which is water with temperature 60ºC, to heat fluid used water heater with power 1000 watt while cold fluid which is air with temperature 25ºC. These four concentric tube heat exchangers with a total length of the first 2.57 m copper tube with 1½ inch diameter. The second copper tube is 2.22 m in diameter of 1 inch. The copper tube is 1.74 m long with a diameter of 1 ¾ inch. The fluid in and out fluid temperature gauges on the heat exchanger can be measured thermocouple which are then processed by software instacall and Tracerdag from a computer through the data acquisition module.

Local wall heat transfer coefficient measurement in a packed bed of cylinders using infrared (IR) thermography technique and application of random packing of cylindrical particles inside concentric tube heat exchangers with water as working medium

Heat transfer enhancement is challenging area in which different techniques are utilized to dissipate the generated heat during operation. Packed beds are devices which enhance heat transport while being compact and are used in several applications such as energy storage, heat exchange devices, catalysis, food processing etc. In the present study, the behavior of wall heat transfer coefficient with randomized packing of equal aspect ratio cylinders is investigated. In this work, the local wall heat transfer coefficient is calculated from local wall temperature data obtained using infrared (IR) thermography in packed beds with randomized packing of cylinders under steady state conditions with water as the working fluid. The randomized packing of cylinders is done inside a concentric tube heat exchanger and the heat transfer enhancement is studied. Experiments are conducted for bed to equivalent particle diameter ratio 2 using random packing of mono-dispersed glass cylinders (dcyl = 6 mm and lcyl = 6 mm). The local wall temperatures are measured using an infrared (IR) camera while the fluid flow takes place through the packed beds. In literature, it is found that wall region contribution to heat transfer is above 90%. The comparison of enhancement in heat transfer for both packing of spheres and cylinders inside concentric tube heat exchangers is done and it is observed that the random sphere packing is superior to cylinder packing.

CFD Application on Shell and Double Concentric Tube Heat Exchanger

This work is concerned with the design and performance evaluation of a shell and double concentric tubes heat exchanger using Solid Works and ANSY (Computational Fluid Dynamics).
 Computational fluid dynamics technique which is a computer-based analysis is used to simulate the heat exchanger involving fluid flow, heat transfer. CFD resolve the entire heat exchanger in discrete elements to find: (1) the temperature gradients, (2) pressure distribution, and (3) velocity vectors. The RNG k-ε model of turbulence is used to determining the accurate results from CFD.
 The heat exchanger design for this work consisted of a shell and eight double concentric tubes. The number of inlets are three and that of outlets are also three for all the fluids that pass through the heat exchanger.
 A comparison was made for the numerical and experimental results and it was found that the percentage error for the hot oil outlet temperature was (6.8%) and the percentage error was (- 21%) for cold water outlet temperature.

Computational Fluid Analysis of Triple Concentric Copper Tube Heat Exchanger

Computational Fluid Analysis of Triple Concentric Copper Tube Heat Exchanger

Thermo-fluid dynamic design optimization of a concentric tube heat exchanger

Thermo-fluid dynamic design optimization of a concentric tube heat exchanger

The heat transfer enhancement of concurrent flow and counter current flow concentric tube heat exchangers by using hexagonal boron nitride/water nanofluid

Heat exchangers are used in many applications including chemical, oil, and gas power generation, refrigeration, pharmaceuticals, and food processing. Because of their widespread usage, they have various types to serve at different working conditions. Increasing the performance of heat exchangers has become a very interesting field of study since the efficiency of various industrial and domestic systems depend on them. In this study, a coaxial double tube experimental set-up was prepared, and the effect of using nanohexagonal boron nitride nanofluid as hot working fluid on the heat transfer performance increase was investigated. The experiments were carried out in concurrent flow and counter flow conditions for various hot fluid-flow rates to obtain the heat transfer coefficients. Nanohexagonal boron nitride obtained in powder form was used to prepare the nanofluid by a two-step method. The 4 kg nanofluid containing 2% nanohexagonal boron nitride with 0.5% Triton X-100 as a surfactant in terms of mass ratio was prepared for the experiments. Heat transfer experiments were carried out three times by using the prepared nanohexagonal boron nitride/water nanofluid and pure water as hot fluid to reach more precise results. In the result of this study, the total heat transfer coefficient showed an average improvement of 48.78% for the concurrent flow heat exchanger, while an average improvement of 0.36% was observed in the counter flow conditions compared to the base fluid. This study shows the potential of application of nanohexagonal boron nitride/water nanofluid in heat management applications.

Characterization of a triple concentric-tube heat exchanger with corrugated tubes using Artificial Neural Networks (ANN)

This work presents a model of Artificial Neural Networks (ANNs) capable of accurately predicting the heat transfer rate and pressure drop in a triple concentric-tube heat exchanger (TTHX) with corrugated and non-corrugated inner tubes and involving a fluid typically used in the food industry. Pitch and depth are varied in the case of corrugated tubes. The ANN model was developed and validated using a huge databank including 181 experimental datasets. The best training algorithm is the Bayesian regulation. A back-propagation algorithm, which is considered to be the most common learning method for ANNs, is used in the training and testing of the network. Different network configurations were tested, and the optimum ANN configuration consisted of a network with two hidden layers with 15 and 21 nodes in the first and second layer, respectively. The ANNs results were found to be in good agreement with the experimental data, with the absolute average relative deviation (AARD) being below 1.91% for the heat transfer coefficient and below 3.82% for the pressure drop, respectively. The simplicity of the developed ANN model and its low levels of error for a huge experimental databank are some of the key features of the model.

Exergy transfer characteristics analysis of turbulent heat transfer enhancement in surfactant solution

This paper presents an exergy transfer analysis for turbulent drag reducing surfactant solution flow with and without heat transfer enhancement devices which employ static or dynamic mixers. Heat transfer and pressure drop measurements were performed at an inlet temperature of 297.7–298.2 K in pipe flow with a concentric tube heat exchanger. The environmental temperature in the analysis was set to be 288.2 K in assumption of a cooling system. The experimental range of the Reynolds number was 1.0×104 to 4.2×104. Adding surfactant to a water flow decreases the exergy transfer Nusselt number, Nue, owing to the heat transfer reduction and increases the exergy transfer efficiency, ηeff, by a maximum of 9.3% at high Reynolds numbers at moderate fluid transport distance owing to the drag reduction. Also the secondary flow caused by the enhancement devices increases Nue. The proposed flow performance curve which provides ηeff for an arbitrary Nue shows that ηeff in viscoelastic fluid flow compared to Newtonian fluid flow is small independently of the fluid transport distance, and that the installation of heat transfer enhancement devices has a positive effect on energy-saving in certain ranges of Reynolds numbers and fluid transport distances.

Investigation of thermohydraulic performance of triple concentric‐tube heat exchanger with CuO/water nanofluid: Numerical approach

AbstractIn this study, numerical investigation of CuO/water nanofluids in a triple concentric‐tube heat exchanger has been carried out using a commercial CFD software. The primary objective of this study is to conduct a heat transfer and pressure drop characteristics of water‐based CuO nanofluids under turbulent flow regime. Reynolds number for the nanofluid has also been considered in the range of 2500 to 10,000 with a nanoparticle volume concentration of 0% to 3%. The effects of flow rate, volume concentration of nanoparticles, and flow arrangement on heat transfer performance of nanofluid have been studied for four flow arrangements. The comparison of the performance with and without nanofluid has been done. It was found that thermal performance and overall effectiveness increased with the increase in Reynolds number and volume concentration of nanoparticles in all the four flow arrangements for the considered range of operating parameters.

Experimental investigation on effect of random packing with uniform sized spheres inside concentric tube heat exchangers on heat transfer coefficient and using water as working medium

Concentric tube heat exchangers are used extensively by the energy industry. In the present study, the behavior of overall heat transfer coefficient with randomized packing of uniformly sized spheres inside the concentric tube heat exchangers is investigated at the laboratory scale. In this work, the heat transfer coefficient on the tube side is calculated using the experimental measured hot and cold fluid temperature differences, mass flow rates of hot and cold fluid. The correlations of are used to calculate the convective heat transfer coefficient (ho) on the annular side and tube side of the concentric tubes packed with uniform sized spheres. However, the logarithmic mean temperature difference is the assumption made for the temperature difference across the packed bed. The calculated overall heat transfer coefficient using correlation and experimental measured one are in very good agreement for a given heat load. The reduction in length in comparison to heat exchangers without packing is found to be ∼95%. A packed bed heat exchanger design methodology is presented.