Concentric Heat Exchanger Research Articles

Simulation of heat and pressure transfer in concentric heat exchangers for small industrial scale

Abstract A Heat exchanger is a tool in industry which aims to transfer energy from hot fluid to cold fluid. The amount of heat transferred is an important parameter of the design and performance of heat exchangers. Concentric tube is a type of heat exchanger that is widely used in industries such as material processing and food preparation. One way to get the value of heat transfered before manufacturing a heat exchanger is to carry out computational fluid dynamic simulations. This simulation will make it easier for us to understand the heat transfer phenomenon that occurs from hot fluid to cold fluid. The aim of this study is to calculate how much heat transfer and pressure drop there is in a laboratory scale cocentric tube type heat exchanger. We also get a picture of the pressure drop that occurs due to fluid friction with the inner pipe walls. Experiments and simulations carried out in this study will then be validated. Variations in flow rate on the tube and shell sides are applied. the greater the flow rate, the greater the transfer of heat. The same trend is shown by variations in pressure. The greater the pressure, the greater the pressure drop that occurs. In this study, the pressure drop from the heat exchanger inlet to the heat exchanger outlet was 0.015%.

Experimental Heat Transfer Analysis of a New Turbulator in a Concentric Heat Exchanger Tube: A Full Factorial Design Approach

Abstract People have been looking for alternative energy sources because current sources may be depleted. Furthermore, it is critical to utilize available energy sources as effectively as possible. Turbulators are among the topics to consider when it comes to energy efficiency. In practice, turbulators are often used in exchangers to enhance heat transfer. Putting newly constructed turbulators in determined locations of the constant surface temperature heat exchanger, velocity, temperatures, pressure, and flow measurements have been performed in the inlet and outlet. In the case of using different numbers of turbulators, their placement in different locations, their arrangement at different distances, and their use at different Reynolds, the changes in pressure drop, Nusselt number, friction factor, efficiency, exergy loss rate, and NTU were determined with the full-factor experimental design. When the test data were evaluated, it was seen that as the number of turbulators increased, the thermal efficiency, friction factor, and pressure loss also increased. Using turbulators in different numbers, at different positions, at different distances, and with different Reynolds numbers, the effect ratio on the pressure loss, Nusselt number, and friction factor parameters was detected. In the analyses made, the most efficient parameters on heat transfer were determined, respectively, as Reynolds number (64.55%), the position of turbulators (19.73%), the distance between turbulators (6.09%), and the number of turbulators (5.94%).

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.

Heat transfer enhancement of nanofluids in concentric cylindrical heat exchanger

Two models of heat transfer channels for concentric cylindrical heat exchangers with porous ribs are developed herein to optimize the transfer efficiency of the heat storage reactor channels. Rings and spiral ribs are added to the smooth circular tube inside the reactor. Spoiler holes are arranged in the ribs to reduce the stagnation area around the ribs. The effects of coolant (SiO2–H2O nanofluids), rib shapes, and the number of holes in the rib on the overall performance of the heat storage system were numerically investigated. Results revealed that the 0.5% mass fraction nanofluids are the most suitable working fluid for channel thermal transport in the simulated Reynolds number range. Both ring ribs and spiral ribs reinforce the heat exchange of the pipe to varying degrees. Spiral perforated ribs have superior heat transfer and drag reduction performance compared with ring ribs. The comprehensive performances of spiral ribs are always higher than those of ring ribs under all conditions.

Thermal performance study of heat exchanger by applying nanofluids

The current research proposes a numerical investigation in the triple tubular concentric heat exchanger (TTCHE). Numerical validations of the TTCHE's performance in parallel flow are made. Using the CFD commercial software ANSYS 19.2, temperature variations for the flow of three separate fluids normal-hot–cold (NHC) and cold-hot-normal (CHN) estimates are made through the triple tube's length. When water is supplied, hot fluid always runs through the middle tube, while cold and normal fluid alternately flows along the other tubes. The outside pipe, middle pipe, and inner pipe have respective diameters of 0.1015 m, 0.076 m, and 0.05 m; the tube is 4 m long. The thickness is 1.50 mm of each tube. Then, employing Al2O3 and TiO2 nanofluids in 0.01 %, 0.03 %, 0.05 %, and 0.07 % wt. fractions instead of normal fluid in both scenarios (CHN & NHC), the computed OHTC enhanced upto 19.89 % and 19 % by employing water based Al2O3 and TiO2 nanofluids. The results showed that the HTC increases as the wt. fraction of nanofluids increases. Compared to other arrangements, the NHC has better performance.

Experimental study of the impact of low concentration MgO-distilled water nanofluid on thermal performance of concentric tube counter flow heat exchanger

Experimental study of the impact of low concentration MgO-distilled water nanofluid on thermal performance of concentric tube counter flow heat exchanger

EVALUASI UNJUK KERJA ALAT PENUKAR KALOR JENIS CONCENTRIC DENGAN VARIASI KECEPATAN ALIRAN FLUIDA KERJA

Heat transfer is a science of heat transfer energy that is indispensable for analyzing the heat transfer process. One type of heat exchanger that is widely used is the Concentric heat exchanger. From the explanation of the theory that the influence of increasing the flow velocity of the cold fluid will affect the increase in the value of the performance of the heat exchanger. Therefore, this influence will provide an increase in heat transfer performance, especially at the heat transfer rate, (Q), heat transfer coefficient (U), and also heat transfer effectiveness (ε). By increasing the variation in the flow velocity of cold fluid by setting the temperature of the hot fluid (Thi) at 45°C and the temperature of the cold fluid (Tci) at 27°C and also made constant up to the highest velocity variation in the cold fluid. From the most minimum performance value at a cold fluid flow rate of 0.067 m/s to 0.134 m/s in the concentric heat exchanger type, performance values were obtained including the heat transfer rate (Q) from 714.09 Watts to 1111.51 Watts on the heat side and 619.89 Watts to 901.83 Watts on the cold side, for the heat transfer coefficient (U) a value of 337.90 W / m2 was obtained. C to 405.38 W/m2. C , and for the effectiveness (ε) which was originally 29% to 43%.

Simulation and optimization of square fin concentric tube heat storage exchanger

The square fin was used to improve the heat transfer rate of the concentric tube phase change heat exchanger. The effects of fin spacing, fin arrangement, and fin length on the melting process of phase change material (PCM) were studied. The influence and mechanism of non-uniform fin arrangement were discussed in detail. The liquid phase distribution and temperature distribution of PCM with time were analyzed. The results indicated that the heat exchanger with square fins can significantly improve the heat storage rate and shortened the complete melting time of PCM. Compared with heat exchangers without fins, the melting time of PCM in a 40 mm equidistant fin heat exchanger was shortened by 15.85%, and that in a 70 mm, non-uniformly spaced fin heat exchanger was shortened by 36.79%. Due to the different distances between the square fins and the outer boundary of the concentric tube, the temperature distribution near the square fin showed anisotropy, which enhanced the melting rate of PCM. The sensitivity order was fin arrangement > fin length > fin spacing. The research results can provide a reference for the design of phase change heat exchangers.

A comparative numerical analysis of concentric and hairpin heat exchanger for efficient energy storage using phase-change material

A comparative numerical analysis of concentric and hairpin heat exchanger for efficient energy storage using phase-change material

Performance optimization of a heat exchanger with coiled-wire turbulator insert by using various machine learning methods

In present study, heat transfer augmentation and pressure loss in a double pipe concentric type heat exchanger with a coiled-wire turbulator inserted in it, are discussed in terms of regression analysis by using various Machine Learning (ML) methods. The non-dimensional design parameters in question are; the Reynolds number (Re), the thickness (e/d), the pitch (p/d) and the length (l/d) of the coiled-wire. Nusselt number (Nu), friction factor (f) and thermal performance factor (η) are the extracted results of the experiments, namely the outputs of the system.In the regression analysis four well-known methods are applied; Supported Vector Regression (SVR), Gaussian Process Regression (GPR), Random Forest (RF) and Multilayer Perceptron Network (MLP) (a kind of Artificial Neural Network (ANN)). The Multi Linear Regression (MLR) method is also applied to the results for comparison. The regression coefficient (R2), mean square error (MSE), mean absolute error (MAE) and root mean square error (RMSE) are the performances obtained by each method.The findings demonstrated that, among the suggested techniques, the MLP and GPR models in particular can be effective tools for calculating Nusselt number, friction factor and thermal performance factor for the selected heat exchanger. The R2 values for Nusselt number, friction factor and thermal performance factor in the MLP model are respectively found to be 1, 0.95 and 0.98. In terms of all performance criteria, the order from best to worst-performing method is as follows: MLP, GPR, SVR and RF. In addition, it was observed that all four methods applied give better results than MLR does.

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.

Numerical and experimental investigation for enhancing thermal performance of a concentric heat exchanger using different scenarios

Purpose Heat exchangers (HEs) which provide heat transfer and transfer energy through direct or indirect contact between fluids have an essential role in many processes as a part of various industries from pharmaceutical production to electronic devices. Using nanofluid as working fluid and integrating different types of turbulators could be used to upgrade the thermal effectiveness of HEs. Recently, to obtain more increment in thermal effectiveness, hybrid nanofluids are used that are prepared by mixing two or more various nanoparticles. The purpose of this experimental and numerical study is investigating different scenarios for improving the effectiveness of a concentric U-tube type HE. Design/methodology/approach In the numerical section of this study, different turbulator modifications, including circular and quarter circular rings, were modeled to determine the effect of adding turbulator on thermal performance. In addition, Al2O3/water and SiO2/water single and Al2O3–SiO2/water hybrid nanofluids were experimentally tested in an unmodified concentric U-tube HE in two different modes, including counter flow and parallel flow. Al2O3–SiO2/water hybrid nanofluid was prepared at 2% (wt./wt.) particle ratio and compared with Al2O3/water and SiO2/water single type nanofluids at same particle ratios and with distilled water. Findings Numerical modeling findings exhibited that integrating turbulators to the concentric tube type HE caused to raise in the effectiveness by improving heat transfer area. Also, experimental results indicated that using both hybrid and single type nanofluids notably upgraded the thermal performance of the concentric U-tube HE. Integrating turbulators cannot be an effective alternative in a concentric U-tube type HE with lower diameter because of raise in pressure drop. Numerically achieved findings exhibited that using quarter circular turbulators decreased pressure drop in comparison with circular turbulators. According to the experimental outcomes, using hybrid Al2O3–SiO2/water nanofluid leads to obtain more thermal performance in comparison with single type nanofluids. The highest increment in overall heat transfer coefficient of HE by using Al2O3–SiO2/water nanofluid achieved as 58.97% experimentally. Originality/value The overall outcomes of the current research exhibited the positive impacts of using hybrid nanofluid and integrating turbulators. In this empirical and numerical survey, numerical simulations were performed to specify the impact of applying different turbulators and hybrid nanofluid on the flow and thermal characteristics in a concentric U-tube HE. The achieved outcomes exhibited that using hybrid nanofluid can notably increase the thermal performance with negligible pressure drop in comparison with two different turbulator modifications.

Enhancing Heat Transfer Performance: Nanofluids Application in Helical Microfin Tube Concentric Heat Exchangers

This manuscript explores the application of nanofluids in helical microfin tube concentric heat exchangers and investigates the potential for improved heat transfer performance. Helical microfin tubes offer enhanced heat transfer characteristics due to increased surface area and improved fluid mixing. When combined with nanofluids, which are base fluids with suspended nanoparticles, the thermal conductivity and convective heat transfer properties can be further enhanced. The objective of this present work is to investigate experimentally on heat transfer enhancement Al2O3/distilled water (0.05 vol.%) flowing through a helical microfin concentric heat exchanger in both parallel and counter flow in the vertical direction. The result is revealed that Al2O3/water nanofluids has enhanced thermal evaluation performance to water as base fluid. Counter flow might exhibit a more balanced performance, with a moderate enhancement in heat transfer while considering the pressure drop compared to parallel flow.

CFD analysis of heat transfer enhancement in a concentric tube counter flow heat exchanger using nanofluids (SiO2/H2O, Al2O3/H2O, CNTs/H2O) and twisted tape turbulators

A concentric tube, counter flow heat exchanger with nanofluids under turbulent flow conditions has been examined using a computational fluid dynamics model. The proposed model consists of Twisted Tape Turbulators (TTT) on the annular side and inside the tube along with different nanofluids. Twisted Tape Turbulators produce a swirl motion within the fluids to increase heat transfer. Al2O3/H2O, SiO2/ H2O, and CNTS/ H2O nanofluids (with varying volume concentrations of 1 %, 2 %, and 3 %) with the turbulent flow (Reynold number Re = 2000 to 10000) were considered to determine three major parameters i.e., heat transfer rate (Q), overall heat transfer coefficient (U) and Nusselt number (Nu). This study resulted in 6.03 %, 16.74 %, and 6.74 % enhancement of overall heat transfer coefficient (U) with a 3 % volume concentration of CNTS/H2O nanofluid, Al2O3/H2O nanofluid, and SiO2/H2O nanofluid, respectively, when equated to without twisted tape tabulators. This analysis shows the maximum value of Nusselt number as 143,136.68 and 140.12 for CNTS/H2O, Al2O3/H2O, and SiO2/H2O, respectively, for the twisted tape tubular arrangement. It is concluded that when using twisted tape turbulator, the heat transfer rate (Q), overall heat transfer coefficient (U), and Nusselt Number (Nu) increase with increasing Reynolds number (turbulent flow conditions) and volume concentrations of nanofluid.Novelty statement: Twisted Tape Turbulators (TTT) arrangement with different concentrations and types of nanofluids combined are infrequent in the study of concentric tube heat exchanger with turbulent flow to obtain enhanced heat transfer.

Comparison study on two LT-PV/T systems with different tubular condensers

The concentric double-tube heat exchanger (CDTHE) proposed in our previous work addresses the limitations of the combined application of conventional loop thermosyphon photovoltaic/thermal (LT-PV/T) systems. Based on this, a novel non-concentric multi-tube heat exchanger (NMTHE) as the condenser of the LT-PV/T system was proposed in this paper, which improves the performance of system by reducing the flow resistance of the working fluid. Experimental platform was built to explore the performance difference between CDTHE-LT-PV/T and NMTHE-LT-PV/T system. Experimental results show that compared with the CDTHE-LT-PV/T system, the thermal efficiency, the electrical efficiency, the primary energy-saving efficiency and the exergy efficiency of NMTHE-LT-PV/T system relatively increase by 17.76%, 2.1%, 10.05% and 3.64%. Mathematical models for two systems are established and verified. Then the performance of the two systems under different solar radiation and ambient temperature is explored. Besides, the all-day performance of the two systems on typical winter days in four cities at different latitudes is predicted. The results show that the NMTHE-LT-PV/T has more prominent advantages in northern China at higher latitude. Furthermore, the influences of some structural parameters and operating setup on the performance of NMTHE-LT-PV/T system are discussed.

FLUID FLOW ANALYSIS OF CONCENTRIC HEAT EXCHANGER WITH DIFFERENT NANO FLUIDS AND MASS FLOW RATES

In this article, the overall performance of water and other nano fluids mixed with base fluid water in a twin pipe warmth exchanger is investigated. At quantity fractions of 0.35 percentage, the nano fluids are Silicon Oxide and silver nano fluid. The traits of nano fluids are decided the usage of theoretical calculations, which can be then utilised as inputs for analysis. CATIA parametric software program is used to create a 3D model of the dual pipe heat exchanger (plain and coil insert tube). CFD research of a dual pipe warmth exchanger with water, silicon oxide, and silver nano particle at diverse mass float fees of zero.32, zero. Fifty two, 0.72,zero.Ninety two, and 1.12 kg/sec is performed. Theoretical calculations on the twin pipe warmness exchanger had been additionally finished.

Detailed evaluation of a heat exchanger in terms of effectiveness and second law

In this study, experiments were conducted to investigate the effects of semicircular strip turbulators placed in the inner tube of a concentric heat exchanger on its exergy loss rate (E*) and effectiveness (e). The Reynolds number (Re), pitch (p), diameter (d), thickness (t) and arrangement style (a) were the design parameters for the study. The changes in these parameters had significant effects on exergy loss rate and effectiveness compared to the results found with the smooth empty tube. The results of the study are given graphically as the change in the exergy loss rate and the change in effectiveness with the number of transfer units (NTU). The largest exergy loss rate and effectiveness values were found to be 0.263 and 0.556, respectively. It was concluded that the effectiveness of the heat exchanger increased with increasing NTU, while the exergy loss rate is decreased. Since the increase in effectiveness will mean an increase in heat transfer, it can also cause an increase in irreversibility. For this reason, multi-performance characteristics have been determined since evaluating the effectiveness together with the exergy loss rate caused by irreversibility will provide more realistic results. Thus, the optimum parameter combination was found, where the maximum effectiveness and the smallest exergy loss rate values were obtained. Finally, the artificial neural network (ANN) model of the study was created and the hyperparameters of the model were determined by the Bayesian optimisation method. In the created ANN model, MSE and R values of effectiveness and exergy loss rate were found as 5.3238e-04, 2.18177e-06 and 0.963, 0.998, respectively. According to these results, it has been confirmed that the proposed ANN model can be used successfully in the modelling of the heat exchanger.

Performance improvement of metal hydride hydrogen storage tanks by using phase change materials

In metal hydride based hydrogen storage tanks, heat transfer fluid (HTF) has been extensively used to continuously transfer the reaction heat for promoting the reaction via heat exchangers. In this study, the phase change material (PCM) is integrated with the tank to enhance heat transfer and recycle the reaction heat. A novel storage tank with a simple concentric straight-tube heat exchanger surrounded by PCM is put forward to improve the hydrogen storage performance. A numerical model is built to track the transfer and reaction process. By comparison, the new tank shows better heat transfer and storage performance, and the hydrogen absorption time is shortened by 60.2% than that of the tank without PCM. For the new tank, the optimal amount of PCM is obtained, based on which the increased absorption pressure could effectively accelerate the heat discharge and reaction rate during the absorption process. However, the increased inlet velocity of HTF has a limited improvement effect on heat transfer and reaction performance. Furthermore, on the PCM side of the tank, the addition of fins and increasing the thermal conductivity of PCM had little effect on the performance of the tank.

Novel Numerical Modeling of Concentric and Lateral Capillary Tube Suction Line Heat Exchangers

Novel Numerical Modeling of Concentric and Lateral Capillary Tube Suction Line Heat Exchangers

Performance Examination of Concentric Tube Spiral Coil Heat Exchanger for Heat Transfer Analysis

Hot fluid passes through the inner tube and cold fluid flows through the outer tube in an experimental study of a Concentric Tube Spiral Coil Heat Exchanger conducted in a Counter Current method. The temperature data was recorded while the flow rates in the inner tube and Annulus were altered five times each. To get total heat transfer coefficients as well as heat transfer coefficients for the inner tube and annulus, the Wilson Plot method is utilised. The Nusselt Number gained from the experiment was compared to the Nusselt Number obtained through the development of a mathematical model using Regression Analysis. The inner Nusselt Number was linked to Dean Number, while the Annulus Nusselt Number was linked to Modified Dean Number and a new Dimensionless Number called "M Number." The experimental data was well-fitting with the Theoretical one. The hydrodynamics (pressure drop) and heat transfer properties of the concentric tube spiral coil heat exchanger were also examined.