Increase In Heat Transfer Research Articles

INVESTIGATION OF THERMAL DISPERSION FOR STEADY AND PULSATING WATER FLOW IN METAL FOAM

The dispersion coefficient in metal foam is critical for analysis and design using the volume-averaged equations. This coefficient is hardly investigated for steady flow, and has not been reported for non-steady flows in metal foam. This paper presents experimental and numerical investigations on the thermal dispersion coefficient in a metal-foam rectangular channel for steady and pulsating water flow. The foam channel was asymmetrically heated from one side representing a heat sink. The heating was accomplished by applying a constant heat flux. For the steady-state investigation, Reynolds number based on the hydraulic diameter of the channel ranged from 365 to 1164. For this range, the experimental thermal dispersion was obtained and given in the form of a correlation. For the pulsating flow investigation, the flow frequency ranged from 0.07 to 0.17 Hz with a maximum velocity amplitude of 0.07 m/s. The thermal dispersion coefficient was obtained experimentally for the pulsating flow in metal foam, most likely for the first time. Results have shown that the velocity amplitude has a significant effect on the thermal dispersion coefficient, whereas the frequency has a limited effect. The dispersion coefficient for pulsating flow was significantly higher than that for steady-state flow, and the difference between the two increased with Reynolds number. This increase in dispersion for pulsating flow is responsible in part for the increased heat transfer.

Heat transfer augmentation through engine oil-based hybrid nanofluid inside a trapezoid cavity

Heat transfer occurs as a result of density differences caused by temperature changes. It has several industrial applications. To improve performance, one must investigate the heat transfer behaviour of the working fluid. Hence, the purpose of this work is to report a heat transfer analysis of a partially heated trapezoid cavity filled with a hybrid nanofluid. The temperature conditions of the cavity are such that the bottom boundary is partially heated, inclined side boundaries are kept at a lower temperature, and the upper boundary is kept adiabatic. A trapezoidal shape heated obstacle is considered in the cavity’s centre. The heat transfer and flow take place inside the cavity due to density variation. The mechanism is regulated by mass, momentum, and energy conservation, as well as related boundary constraints. The solutions are determined by the use of a numerical technique known as the Finite Element Method after the governing equations are transformed into non-dimensional form, which brings up physical parameters affecting the heat transfer and flow. The initial study is performed for three types of nanofluids with silver 𝐴𝑔 and magnesium oxide 𝑀𝑔𝑜 nanoparticles inside water 𝐻2𝑂, kerosene 𝐾𝑒, and engine oil 𝐸𝑂. The study revealed that the engine oil-based hybrid nanofluid produced an increased heat transfer rate. Simulation is performed using engine-based hybrid nanofluid with the range of physical parameters, such as Rayleigh number 𝑅𝑎 (105≤𝑅𝑎≤107), Hartmann number 𝐻𝑎 (0≤𝐻𝑎≤100) and nanoparticles volume fraction 𝜙 (0≤𝜙≤0.2). It is found that the heat transfer rate is enhanced by increasing the fraction of nanoparticles in the base fluid. Moreover, imposition of magnetic field has reverse impact on the fluid movement.

Multiphase Flow Regime Identification in Cryogenic Nitrogen using Electrical Capacitance Measurement Technology

Abstract Understanding and modeling multiphase flow is of vital importance to the design of next-generation cryogenic systems. While many experiments characterizing multiphase flow have been performed on Earth, the behavior of cryogenic systems still needs to be fully described in low gravity and microgravity conditions. As the necessity of cryogenic systems increases for in-space refueling operations, increased heat transfer efficiency, and in-situ resource utilization, the demand for better fluid models, instrumentation, and control systems also increases. In this paper, a capacitance-based flow regime identification algorithm is developed for use with cryogenic systems. Data is collected on a liquid nitrogen system for a wide array of flow regimes in a ½” tube. Quantitative parameters are developed that are able to determine the real-time multiphase flow regime and the algorithm is verified using accepted models, providing much that is needed for the foundation of a multiphase flow regime identification instrument with broad applications in fluid modeling, research, and cryogenic system feedback control.

Numerical and experimental study to examine methods to increase the convectional heat transfer of recuperator tubes

The use of structured tubes in tube bundle recuperators is intended to improve the energy efficiency of gas-fired industrial furnace systems with central air preheating. Currently, smooth tubes as well as smooth tubes with internal twisted tape are commonly utilised. The increased surface area of structured tubes leads to an increased heat transfer between the off-gas and the combustion air. However, structuring leads to an increased pressure loss. The aim is to find an optimal operating range in which the pressure losses are still acceptable and the greatest increase of heat transfer compared to the reference will be achieved. Smooth tubes and also smooth tubes with twisted tapes are considered as reference systems in comparison to two concave structured tubes. CFD simulations were used to investigate the influence of the operating parameters of combustion air velocity and off-gas velocity on heat transfer according to industrial scale. The simulations have shown that the heat flow increases with the honeycomb depth and strongly depends on the operating conditions. Experimental measurements in a test bench were carried out to validate the model and confirm the positive influence of structuring on heat transfer.

Aspects of Dual Simulation for Modified Thermal Flux Advances in Non‐Newtonian Reiner–Philippoff Fluid Flow past a Shrinking Plate Embedded in a Porous Medium

This study investigates the effects of non‐Newtonian Reiner–Philippoff fluids on porous media, particularly in the context of steady radiative mixed convection flow and heat transfer near a shrinking plate surface in the presence of magnetohydrodynamics (MHD). The mathematical model is constructed using PDEs and transformed into ODEs via similarity transformations, with numerical solutions obtained using MATLAB’s bvp4c function. The results demonstrate that boundary layer separation occurs slowest for dilatant fluids and fastest for pseudoplastic fluids, with Newtonian fluids exhibiting moderate separation rates. Thermal radiation and media porosity parameters are found to reduce heat transfer by approximately 0.95% and 0.02%, respectively, while accelerating boundary layer separation. Conversely, magnetic effects and suction parameters increase heat transfer by about 0.08% and 4.25%, respectively, enhancing both fluid velocity and temperature. The mixed convection parameter indicates the possibility of dual solutions, with the opposing flow favoring this phenomenon more than the assisting flow. The time‐based stability analysis reveals that the first solution is stable, whereas the second solution is unstable. These findings provide significant insights into the behavior and control of Reiner–Philippoff fluids in practical applications involving porous media and magnetic fields.

Numerical Study and Structural Optimization of Impinging Jet Heat Transfer Performance of Floatation Nozzle

A floatation nozzle can effectively transfer heat and dry without touching the substrate, and serves as a vital component for heat transfer to the substrate. Enhancing the heat transfer performance, and reducing its heat transfer unevenness to the substrate play an important role in improving product quality and reducing thermal stress. In this work, the effects of key structural parameters of the floatation nozzle on the heat transfer mechanism are systematically investigated by means of a numerical simulation of computational fluid dynamics. The findings demonstrate that the secondary vortex structure induced by the floatation nozzle with effusion holes increases heat transfer performance by 254.3% compared with the nozzle without effusion holes. The turbulent kinetic energy and temperature distribution between the jet and the target surface are affected by the jet angle and slit width respectively, which change the heat transfer performance of the float nozzle in different degrees. Furthermore, to improve the comprehensive heat transfer performance of the floatation nozzle structure, taking into account the average heat transfer capability and heat transfer uniformity, the floatation nozzle’s design is optimized by the application of the response surface method. The comprehensive heat transfer performance is increased by 26.48% with the optimized design parameters. Our work is of practical value for the design of floatation nozzles with high heat transfer performance to improve product quality in industrial systems.

Design, Analysis and Optimization of Fin-and-Tube Type Heat Exchanger in Marine Diesel Engine

Despite diesel engine technology seems close to be ending with decrease of electrical vehicles, it still has potential in marine, heavy-duty, and industrial areas. Marine diesel engines are frequently encountered in yachts, towing boats, and sailing boats. The cooling fluid is sea water in marine engines. The engine coolant water is cooled by shell and tube heat exchangers. Charge air is cooled by fin-and-tube type heat exchangers. In this study, fin-and-tube type heat exchanger’s design and flow analysis were investigated for the prototype six-cylinder inline engine. Heat exchanger’s header geometry was optimized to increase heat transfer, and an acceptable header design was decided upon with the analysis results.

Thermocapillary convection modes and phase change heat transfer characteristics of three-dimensional metal foam composited phase change materials with different aspect ratios under microgravity

This work aims to investigate the flow, heat transfer and phase change characteristics of porous media composite phase change materials with different aspect ratios in the thermocapillary mode under microgravity. A three-dimensional hydrodynamic model of thermocapillary-enhanced phase change heat transfer in the composite is developed. The model considers the shear stress boundary conditions on the porous free surface, employing the enthalpy-porosity method and the Darcy–Forchheimer model to describe the phase change process and fluid flow within the porous matrix, respectively, and the local thermal non-equilibrium model to describe the transient heat energy transfer between the paraffin and copper foam. The effects of different Marangoni numbers (Ma), aspect ratios (AR), Darcy numbers (Da) and porosities (ε) on the phase change heat transfer are compared. The results show that the increase of Ma from 6 × 104 to 2 × 105 accelerates the thermocapillary effect, and positively affect the thermal transport inside the cavity. The total melting time of the composite is reduced by 22.6 %, the heat storage efficiency is improved by 31.1 %, and secondary vortices appear in the convection zone. The large AR is favorable to the development of thermocapillary convection, but it also causes the reduced temperature gradient and heat transfer area of the heat source as well as the increased heat transfer distance. Compared to AR = 1, the total melting time increased by 34.4 % and 46.9 % for AR of 1.95 and 2.25 at a larger Ma, while the heat storage efficiency decreased by 26.5 % and 33.7 %, respectively. For a fixed ε, the decrease in Da hinders the development of convection, thus weakening the heat transfer and storage performance of the composite, and also causes heat conduction to dominate the phase change process in advance.

Экспериментальное исследование осциллирующего течения в трубном пучке

Oscillating reciprocating flows are found in a variety of engineering applications. The mechanisms of oscillating flows have not been sufficiently studied. Oscillating flows can be created artificially to increase heat transfer equipment by intensifying heat transfer. Thus, this paper studies the flow and heat transfer characteristics of a tube bundle under the influence of oscillating flow. The assessment of heat transfer and the hydrodynamic flow pattern in a tube bundle during flow oscillations is carried out on the basis of experimental studies. Flow oscillations have been created by a pneumatic system that drove a pulsator. The time characteristic of the pressure drop of the tube bundle has been recorded using an oscilloscope and pressure drop sensors. To assess the dynamics of flow velocity, the high-speed shooting method is used. The heat exchange of a tube bundle has been determined by the electrical power expended to maintain a constant temperature on the tube side of the bundle. For the first time, heat transfer and the hydrodynamic flow pattern with asymmetrical flow oscillations in an inline tube bundle are studied experimentally. It is shown that the shape of oscillations of flow velocity and pressure drop depend on frequency. It has been found that with increasing frequency there is an increase in the values of flow velocity and pressure drop. It has been determined that for certain moments of time, the flow velocity and pressure drop during asymmetrical oscillations exceed symmetrical ones. It has been established that the heat transfer rate of a bundle increases by 1,7 times with an increase in frequency. It has been shown that asymmetrical oscillations are more effective in intensifying heat transfer than symmetrical ones by an average of 1,1 times. Analysis of the results obtained has showed the possibility of intensifying heat transfer in a tube bundle using oscillating flows. Thus, oscillating flows can be used to increase the efficiency of heat exchange equipment. The results obtained on the hydrodynamic flow pattern can be used in mathematical modeling of oscillating flows, which are necessary to expand the operating parameters of the study and determine the most effective ones.

Novel Cooling Strategy for a Hybrid Photovoltaic/Parabolic Dish Concentrator

In this paper, the thermo-optical performance using novel cooling strategy improvements for a hybrid photovoltaic/parabolic dish concentrator with a conical thermal receiver using a beam splitter filter (PV/PDC-CTR-BSF) is investigated. The study’s main goal is to improve the cooling effectiveness of the serpentine-shaped cooling duct by investigating the effect of the cross-section shape and positioning of the cooling duct under the PV panel. Typical cooling pipes have either a rectangular or circular cross-section and are usually attached to the back sheet of the PV panel using off-the-shelf adhesives that have very low thermal conductivity. With the advent of 3D printing technology, the back sheets could be 3D-printed with integral cooling ducts of different cross-sections at different locations and orientations within the back sheet that allow for increased heat transfer from the back sheet and thus improve PV/PDC-CTR-BSF’s thermos-optical performance. For this purpose, the study investigates and compares the thermal performance of four different cooling duct cross-sections that include: rectangular, semi-circular, semi-elliptical and triangular. For each of the cooling duct cross-sections, several positions and orientations, which include flush below the back sheet layer and embedded inside the back sheet but positioned at the bottom, middle and top of the back sheet, are examined. Numerical simulations using the commercial software ANSYS FLUENT(R2019) are performed to assess the performance of the cooling ducts and, in turn, the thermo-optical performance of the PV/PDC-CTR-BSF system. The semi-elliptical cross-section duct embedded in the middle of the back sheet was found to yield the best cooling performance since its rate of heat removal from the PV back sheet was found to be the highest.

Enhancement of pool boiling performance through an asymmetric dual V-groove microchannel structured surface

In pool boiling, microchannels on the heated surface change the bubble dynamics and consequently improve the heat transfer. In this study, two new microchannel configurations, i.e., asymmetric dual V-groove microchannels (VM) and orthogonally intersecting asymmetric dual V-groove microchannels (OIVM) have been introduced to study enhancement in pool boiling. The heat transfer enhancement due to the modified surfaces was established by comparing the heat transfer rates from the reference flat surface. Experiments have been performed using deionized water under saturation temperature at one atmosphere to evaluate the steady state heat transfer characteristics. The bubble dynamics and interface morphology at various heat flux levels have been captured using high-speed camera. The experimental observations have revealed that both the microchannel configurations exhibit a substantial improvement in heat transfer compared to that of flat surfaces. The OIVM surface demonstrates the highest rates of heat transfer and increase of 5.3 times in the maximum heat transfer coefficient (HTC) and 2.4 times in the critical heat flux (CHF) were observed compared to that of flat surfaces. Similarly, the VM surface demonstrates an improvement of 2.2 fold in HTC and 1.7 fold in CHF compared to the flat surface. Moreover, the OIVM surface demonstrates better heat transfer rates than that of modified surfaces investigated in the past studies. The increased heat transfer rate with the OIVM surface can be ascribed to large area for heat exchange, increased bubble initiation sites, bubble motion promoted macroconvection and efficient rewetting mechanism.

Experimental investigation of PCM melting with graphite/aluminum alloy “sandwich” plate of high thermal conductivity

This work proposed the “sandwich” structure of the graphite/aluminum alloy high thermal conductivity plate. The study is focused on the heat dissipation effect of graphite/aluminum alloy “sandwich” plate (GASP) in the phase change heat storage heat sink. Firstly, the equivalent thermal conductivity of the GASP was measured experimentally. Then melting experiments were performed with heating powers of 15 W, 20 W, and 30 W in the cavity with pure paraffin, aluminum alloy plate, and GASP. Phase and temperature field visualization are observed by the digital camera and infrared thermal imager combined with thermocouples at the vertical-mid plane inside the cavity, respectively. Visualized images revealed that the existence of the GASP dominates the melting direction of the paraffin perpendicular to the plate and shortens the melting distance of the paraffin. Melt fractions, absorbed energy, and Nusselt numbers can be obtained from experimental data based on the melting process. Furthermore, the melting enhancement ratio was defined and thermal control performance was investigated. Experiment results indicated that adding GASP increased the melting rate and decreased the melting time. The melting enhancement ratio decreased with raising the heating power which indicates GASP is more effective at lower heat flux. Meanwhile, the positive optimization of increasing heat transfer area on melting exceeds the negative effect of decreased Nusselt number.

Enhanced electrolytic immersion cooling for thermal crisis mitigation in high-energy–density systems

Motivated by the increasing need for effective cooling solutions in high-energy–density systems, this experimental study presents the two-phase cooling of a superheated SS 316L sample via immersion quenching in saturated deionized (DI) water at atmospheric pressure conditions with and without a DC electric field. We investigate the effect of the applied electric field, electrode polarity, and in-situ oxidation on quenching characteristics such as the cooling profile, vapour layer behaviour, minimum film boiling temperature (Tmin), and heat transfer rate. The cooling curves of samples quenched with the application of an electric field shift towards the left compared to the sample quenched without an electric field. The cathode sample at 200 V exhibits 33 % faster cooling than the bare sample (0 V). Overall, the in-situ oxidised SS 316L cathode sample at 200 V exhibits a 55 % reduction in film boiling duration, and Tmin increased from 268 °C to 322 °C compared to the bare sample (0 V). The visualisation studies highlight that the liquid–vapour interface experiences a series of oscillations followed by temporal collapse due to electrostatic attraction and electrolytic activity. The obtained results show that hydrogen-rich vapour bubbles increase heat transfer performance. The evolution of hydrogen and its adsorption at the sample surface reduces the activation energy for bubble nucleation and improves the bubble density via liquid pumping. These insights open the pathway for employing hydrogen bubbles for handling ultra-high thermal loads in high-energy density systems, and the specific case of a revised design of concentrating solar receiver is considered based on the present findings.

Improving the thermal performance of the heat exchanger through simultaneous utilization of novel magnetic turbulators and helical coil wire turbulators

In this study, the effect of simultaneously using two active and passive methods, namely the magnetic turbulator and the helical coil wire (HCW) turbulator, on the hydrothermal parameters of a double tube heat exchanger is being evaluated for the first time. The results are also being compared with those of a simple heat exchanger, a heat exchanger equipped with a magnetic turbulator, and a heat exchanger with a HCW turbulator insert. Finally, the most optimal option is selected using TEF. Tests have been conducted using different pitch ratios of the HCW turbulator (ranging from 2.5 to 10) and fluid flow rates (ranging from 0.5 to 4 l/min). According to the results, the usage of the HCW turbulator, magnetic turbulator, and the simultaneous use of both turbulators increases heat transfer by 237 %, 262 %, and 491 %, respectively. Additionally, the pressure drop in the presence of these two methods is 3.8 times that of a simple heat exchanger. Furthermore, with the help of TEF, the heat exchanger armed with both turbulators is chosen as the optimal option, achieving a TEF of 3.78.

Experimental study on mechanical, damping and corrosion properties of Inconel 718 hard-faced stainless steel 304 using cold metal transfer

Cold Metal Transfer process is used to hard-face the Inconel 718 alloy onto the Stainless Steel 304 material. The optimized parameters from the Bead on Plate trials were determined as a wire feed rate of 7 m/min, deposition speed of 15 cm/min, welding current, and voltage of 175 A and 14.9 V, respectively. Hard-facing is carried out with the sinewave weaving technique along 30 % of overlapping beads. The analysis is focused on revealing the hard-faced specimens' microstructural, mechanical, and electrochemical corrosion properties. The hard-face layer exhibits grains of mixed modes, including columnar, cellular, and fine equiaxed grains. The increased heat transfer disintegrates grain formation and reduces secondary arm spacing development. SEM-Elemental mapping shows the reduction of Niobium (3.61 %) segregation and laves formation. The overlay layer has a maximum hardness of 343.1 HV0.5 over the base substrate with 204 HV0.5. The impact test reveals the hard-faced layer absorbs more energy (26.3 %) than the substrate. Dynamic Mechanical Analysis results indicate overlay layer enhancing damping properties. The electrochemical corrosion test findings suggest that the hard-faced layer's high corrosion potential (Ecorr = 8.533 mV) corresponds to a high corrosion resistance. Phase and intermetallic formations, distribution of elements, fractured and corrosive surface morphologies are analyzed using SEM, EDX, and elemental mapping results.

Numerical study of falling film flow and heat transfer on the horizontal tube with a porous coating layer

Porous surfaces often exhibit exceptional performance in liquid spreading and heat transfer, making them promising candidates for enhancing falling film heat transfer on solid surfaces. This paper delves into the flow and heat transfer characteristics occurring within falling films on horizontal tubes coated with a porous layer. To achieve this, a three-dimensional numerical model that couples the Volume of Fluid (VOF) method with porous media considerations was employed. The investigation comprehensively covers film spreading behavior, flow patterns, film velocity, film thickness, temperature distribution, and heat transfer coefficients, for both plain and porous tubes. Furthermore, we delve into the effects of key parameters, such as porosity, layer thickness, and material properties, on the overall heat transfer process. The results demonstrate the accuracy of our model in reproducing film thickness and heat transfer coefficients within falling films on horizontal porous tubes. When comparing plain tubes to porous ones, some key differences emerge. Specifically, the liquid film on porous tubes spreads more slowly, leading to increased film thickness and fewer occurrences of dry patches. Additionally, porous tubes result in lower film velocity and a more uniform temperature field compared to plain tubes. Interestingly, the findings reveal that smaller porosities yield thicker films and higher heat transfer coefficients, particularly when the porosity is below 0.4. Moreover, thicker porous layers result in thinner films, higher wetting ratios, and increased heat transfer coefficients. Among the materials we tested, aluminum and copper porous layers exhibit the highest heat transfer performance, while steel demonstrates the lowest.

Numerical treatment for the desirability of Hall current and activation energy in the enhancement of heat transfer in a nanofluidic system

The growing attractiveness of Artificial Neural Networks (ANNs) derives from their exceptional effectiveness in handling difficult and exceptionally nonlinear mathematical ideas. In complicated disciplines such as fluid mechanics, biological computation, and the field of biotechnology ANNs provide a diverse computing framework that is extremely valuable. This article's major aim is to harness the capabilities of the Levenberg-Marquardt technique with backpropagation intelligent neural networks (LM- BPINNs) to study there is still a lack of clarity regarding the mechanics underlying the increased heat transfer caused by dispersed nanoparticles. The using proposed LM-BPINNs to improve the heat transmission use activation energy and Hall current phenomena in nanofluid (HTAHCNF). The data set is obtained by using Lobatto-III. A method and then ANNs is applied. The LM- BPINNs technique is applied by utilizing reference datasets, with 80% of the dataset devoted to training, 10% to testing, and 10% to verification. The precision/accuracy and converging of developed LM- BPINNs are validated based on the obtained reliability via efficient fitness achieved on mean squared error (MSE), comprehensive regression analysis, and appropriate error histogram visualizations. A diminished MSE indicates that the model's predictions are more reliable. The outcome is consistent with getting a minimal absolute error close to zero, exhibiting the effectiveness of the proposed approach.

Cascading latent heat thermal energy storage in parabolic trough solar collector as a promising solution: An experimental investigation

Solar energy system can be considered as a reliable energy source if it connects to a latent heat thermal energy storage (LHTES) system using phase change materials (PCMs). To tackle the low thermal conductivity coefficient of PCMs, the cascaded latent heat storage (CLHS) configuration is a promising solution. This study aims to illustrate the improvement of CLHS setup comparing with non-cascaded arrangement, performing a whole-scale experimental investigation. A compact parabolic trough collector (PTC) unit equipped with a LHTES module is designed and constructed for a residential purpose. Experimental results reveal that the average thermal efficiency of PTC is 73.5 %. Three paraffin waxes with melting ranges of (64–68 ℃), (57–60 ℃) and (46–48 ℃) are injected in three same series of shell-tube heat exchangers. For comparing cascaded and non-cascaded PCM performance, three experimental series, namely (Exp.1, Exp.2 and Exp.3) are performed. The experimental findings show that the deployment of the CLHS configuration improves the latent heat storage of non-CLHS-Exps.1, 2, and 3 by more than 10, 47, and 5 %, respectively. In addition, CLHS system has a potential to increase the exergy storage of non-CLHS setup by up to 27.4 %. Furthermore, impact of increasing heat transfer fluid (HTF) flow rate is examined and it is observed that the melting process is shortened by almost 39 %. Accordingly, increasing flow rate improves energy stored in PCMs1, 2, and 3 by 60 %, 59.62 %, and 72.04 %, respectively. Consequently, the latent thermal exergy storage of the PCM experiences a twofold increase. Conducting an experimental evaluation of thermal performance of the storage module integrated with PTC setup can be valuable, particularly in the realm of residential applications.

Optimized Design of Shell and Tube Heat Exchanger with Segmental Baffles

Heat exchangers are the apparatus which is widely used in various industries. They transmit heat among two or more fluid streams. Theoretical analysis done by Kern’s method has been done on Shell and tube heat exchanger with segmental baffle and then experimented in CFD to check Heat Transfer rate and pressure drop with varying number of baffles which is 6, 8 and 10, and by keeping all the rest of parameters constant. It is found that as the number of baffles increase heat transfer rate increases also pressure drop is increases significantly. To optimize model in next step, CFD analysis is has been done by varying baffle cut to 25%, 35% and 45% by keeping same number of baffles which found best in heat transfer rate in earlier Kern’s method. Other parameters like velocity, temperature, pressure and baffle numbers are kept constant. Results obtained from numerical solution are analysed extensively to get the effect of baffle cut on heat transfer rate and pressure drop on shell side. The pressing need of the heat exchanger industry, the tradeoff optimization between the pressure drop and the heat transfer coefficient has been studied to provide an idea to get effects of the change in two parameters, namely, baffle spacing and baffle cut simultaneously and observe how these two will affect the performance of an STHX. An attempt to find the optimum geometric configuration has been carried out with number of baffles. Increasing baffles for same length of shell and baffle cut increases from 25% to 35%, heat transfer rate increases. It is beneficial in elucidating that a higher heat transfer coefficient can be obtained for fewer baffles when coupled with the appropriate baffle cut. So selection of correct optimized shell and tube heat exchanger. The work is carried out for copper tube bundles and steel shell. So optimization of baffle cut with correct number of baffles and reduction in pressure drop studied with CFD tool.

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.