BITS Faculty Publications
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Item Research Article Investigation of Counterflow Microchannel Heat Exchanger with Hybrid Nanoparticles and PCM Suspension as a Coolant(MDPI, 2021-03) Bhattacharyya, SuvanjanA circular tube fitted with novel corrugated spring tape inserts has been investigated. Air was used as the working fluid. A thorough literature review has been done and this geometry has not been studied previously, neither experimentally nor theoretically. A novel experimental investigation of this enhanced geometry can, therefore, be treated as a new substantial contribution in the open literature. Three different spring ratio and depth ratio has been used in this study. Increase in thermal energy transport coefficient is noticed with increase in depth ratio. Corrugated spring tape shows promising results towards heat transfer enhancement. This geometry performs significantly better (60% to 75% increase in heat duty at constant pumping power and 20% to 31% reduction in pumping power at constant heat duty) than simple spring tape. This paper also presented a statistical analysis of the heat transfer and fluid flow by developing an artificial neural network (ANN)- based machine learning (ML) model. The model is evaluated to have an accuracy of 98.00% on unknown test data. These models will help the researchers working in heat transfer enhancementbased experiments to understand and predict the output. As a result, the time and cost of the experiments will reduce. The results of this investigation can be used in designing heat exchangersItem The Influence of Forced Convective Heat Transfer on Hybrid Nanofluid Flow in a Heat Exchanger with Elliptical Corrugated Tubes: Numerical Analyses and Optimization(MDPI, 2022-03) Bhattacharyya, SuvanjanThe capabilities of nanofluids in boosting the heat transfer features of thermal, electrical and power electronic devices have widely been explored. The increasing need of different industries for heat exchangers with high efficiency and small dimensions has been considered by various researchers and is one of the focus topics of the present study. In the present study, forced convective heat transfer of an ethylene glycol/magnesium oxide-multiwalled carbon nanotube (EG/MgO-MWCNT) hybrid nanofluid (HNF) as single-phase flow in a heat exchanger (HE) with elliptical corrugated tubes is investigated. Three-dimensional multiphase governing equations are solved numerically using the control volume approach and a validated numerical model in good agreement with the literature. The range of Reynolds numbers (Re) 50 < Re < 1000 corresponds to laminar flow. Optimization is carried out by evaluation of various parameters to reach an optimal case with the maximum Nusselt number (Nu) and minimum pressure drop. The use of hybrid nanofluid results in a greater output temperature, a higher Nusselt number, and a bigger pressure drop, according to the findings. A similar pattern is obtained by increasing the volume fraction of nanoparticles. The results indicate that the power of the pump is increased when EG/MgO-MWCNT HNFs are employed. Furthermore, the thermal entropy generation reduces, and the frictional entropy generation increases with the volume fraction of nanoparticles and Re number. The results show that frictional and thermal entropy generations intersect by increasing the Re number, indicating that frictional entropy generation can overcome other effective parameters. This study concludes that the EG/MgO-MWCNT HNF with a volume fraction (VF) of 0.4% is proposed as the best-case scenario among all those considered.Item Optimization of heat transfer in shell-and-tube heat exchangers using MOGA algorithm: adding nanofluid and changing the tube arrangement(Taylor & Francis, 2021-10) Bhattacharyya, SuvanjanThe purpose of this study is to assess the impact of a wide variety of parameters to maximize the heat transfer rate using nanofluid, baffles, different Reynolds numbers (Re), different tube arrangements, and various geometry dimensions using the multi-objective genetic algorithm (MOGA) algorithm. The ANSYS FLUENT software, the SIMPLE algorithm as well as single-phase approach are employed for simulations. The study was performed for volume fractions (φ) of 0% to 4% and 10,000 < Re < 20,000. The results are presented for rectangular and triangular arrangements of tubes. It is demonstrated that in the rectangular configuration, the average Nusselt number (Nuave) is 34.38 when number of baffles (NB) of 10, φ = 4%, Re = 20,000. For the same values of φ and Re, when NB = 10, Nuave is enhanced by 7.4% and 10.4% compared to the cases in which NB = 6 and 8, respectively. However, for the triangular arrangement of tubes, Nuave=35.15. For the same values of φ and Re, when NB = 10, Nuave is enhanced by 5.7% and 11.4% compared to the cases in which NB = 6 and 8, respectively. Also, the triangular arrangement has about 2.1% more thermal efficiency than the rectangular one when NB, φ, and Re are maximum. Unlike the smaller figure for tubes mounted in the heat exchanger to transfer heat compared to other studies, the addition of nanofluid and using baffles lead to employing the heat exchanger for practical applications. However, a larger number of baffles causes a higher pressure drop. Hence, the optimization is performed using MOGA to reduce the pressure dropItem Computational heat transfer analysis of a counter-flow heat exchanger with fins(RDME, 2015) Bhattacharyya, SuvanjanA numerical work has been conducted to examine laminar flow and heat transfer characteristics in a two-dimensional isothermal-fluxed circular-duct fitted horizontal with finned tapes. The computations are based on the finite volume method with the SIMPLE algorithm implemented. This paper reports the Computational Fluid Dynamics (CFD) modelling studies on heat transfer, friction factor and thermal performance of a counter-flow heat exchanger equipped with two types of tube insert including fins. The principle of heat transfer enhancement in the core flow of tube has been proposed to improve the temperature uniformity and heat transfer enhancement in the boundary flow of tube. The studied the temperature profile and velocity profile was obtained by the fins inserts with an inclined angle of 90°. The results have also revealed that the difference between the heat transfer rates obtained from two models with fins and without fins. The CFD predicted results were used to explain the observed results in terms of swirl intensity.Item Investigation of Counterflow Microchannel Heat Exchanger with Hybrid Nanoparticles and PCM Suspension as a Coolant(Hindawi Publishing Corporation, 2021) Bhattacharyya, SuvanjanThe effect of the hybrid suspension on the intrinsic characteristics of microencapsulated phase change material (MEPCM) slurry used as a coolant in counterflow microchannel heat exchanger (CFMCHE) with different velocities is investigated numerically. The working fluid used in this paper is a hybrid suspension consisting of nanoparticles and MEPCM particles, in which the particles are suspended in pure water as a base fluid. Two types of hybrid suspension are used (Al2O3 + MEPCM and Cu + MEPCM), and the hydrodynamic and thermal characteristics of these suspensions flowing in a CFMCHE are numerically investigated. The results indicated that using hybrid suspension with high flow velocities improves the performance of the microchannel heat exchanger while resulting in a noticeable increase in pressure drop. Thereupon, it causes a decrease in the performance index. Moreover, it was found that the increment of the nanoparticles’ concentration can rise the low thermal conductivity of the MEPCM slurry, but it also leads to a noticeable increase in pressure drop. Furthermore, it was found that as the thermal conductivity of Cu is higher than that for Al2O3, the enhancement in heat transfer is higher in case of adding Cu particles compared with Al2O3 particles. Therefore, the effectiveness of these materials depends strongly on the application at which CFMCHE is employed.Item Applications of Heat Transfer Enhancement Techniques: A State-of-the-Art Review(Intechopen, 2020-06) Bhattacharyya, SuvanjanThe fundamentals of heat transfer and its applications, the classification of heat transfer technology and different heat transfer techniques, and the needs for augmentation and its benefits and the different combinations of two or more inserts and integral roughness elements for heat transfer augmentation purpose have been introduced and discussed in this chapter. It is shown that most of the compound techniques performed better than the individual inserts for heat transfer enhancement. This chapter has also been dedicated to understanding the basic concepts of vortex generators for heat transfer enhancement in plate-fin heat exchangers. The performance of transverse, longitudinal, and wing-type vortex generators has been discussed as well.Item Heat and Fluid Flow Analysis and ANN-Based Prediction of A Novel Spring Corrugated Tape(MDPI, 2021-03) Bhattacharyya, SuvanjanA circular tube fitted with novel corrugated spring tape inserts has been investigated. Air was used as the working fluid. A thorough literature review has been done and this geometry has not been studied previously, neither experimentally nor theoretically. A novel experimental investigation of this enhanced geometry can, therefore, be treated as a new substantial contribution in the open literature. Three different spring ratio and depth ratio has been used in this study. Increase in thermal energy transport coefficient is noticed with increase in depth ratio. Corrugated spring tape shows promising results towards heat transfer enhancement. This geometry performs significantly better (60% to 75% increase in heat duty at constant pumping power and 20% to 31% reduction in pumping power at constant heat duty) than simple spring tape. This paper also presented a statistical analysis of the heat transfer and fluid flow by developing an artificial neural network (ANN)-based machine learning (ML) model. The model is evaluated to have an accuracy of 98.00% on unknown test data. These models will help the researchers working in heat transfer enhancement-based experiments to understand and predict the output. As a result, the time and cost of the experiments will reduce. The results of this investigation can be used in designing heat exchangers.Item Numerical Investigation of Thermohydraulics Performance in Elliptical Twisted Duct Heat Exchanger(Springer, 2016) Bhattacharyya, SuvanjanHeat transfer behaviour in twisted elliptical duct swirl generator is investigated numerically. Twisted geometry is a widely used technique for heat transfer enhancement. This work presents the investigation of a elliptical twisted duct (ETD) for turbulent heat transfer in air using computational fluid dynamics (CFD) modelling. In the present paper, transition—SST model which can predict the change of flow regime from laminar through intermittent to turbulent has been used for numerical simulations. While the aspect ratio of major and minor axes of the elliptical duct is 0.5, the pitch length (Y) is varied between 0.5 and 1.0. The results indicate that the smaller pitch length yields a higher heat transfer value with relatively lower performance penalty. The transition from laminar to turbulent regime is observed between Reynolds numbers of 1000–3500 for all cases. For all investigated cases, heat transfer enhancement (η) tends to increase with the increase of Reynolds number. This result is useful for the design of solar thermal heaters and heat exchangers.Item Turbulent Flow Heat Transfer through a Circular Tube with Novel Hybrid Grooved Tape Inserts: Thermohydraulic Analysis and Prediction by Applying Machine Learning Model(MDPI, 2021-03) Bhattacharyya, SuvanjanThe present experimental work is performed to investigate the convection heat transfer (HT), pressure drop (PD), irreversibility, exergy efficiency and thermal performance for turbulent flow inside a uniformly heated circular channel fitted with novel geometry of hybrid tape. Air is taken as the working fluid and the Reynolds number is varied from 10,000 to 80,000. Hybrid tape is made up of a combination of grooved spring tape and wavy tape. The results obtained with the novel hybrid tape show significantly better performance over individual tapes. A correlation has been developed for predicting the friction factor (f) and Nusselt number (Nu) with novel hybrid tape. The results of this investigation can be used in designing heat exchangers. This paper also presented a statistical analysis of the heat transfer and fluid flow by developing an artificial neural network (ANN)-based machine learning (ML) model. The model is trained based on the features of experimental data, which provide an estimation of experimental output based on user-defined input parameters. The model is evaluated to have an accuracy of 98.00% on unknown test data. These models will help the researchers working in heat transfer enhancement-based experiments to understand and predict the output. As a result, the time and cost of the experiments will reduce.Item Fluid Flow and Heat Transfer in a Heat Exchanger Channel with Short-Length Twisted Tape Turbulator Inserts(Springer, 2018-09) Bhattacharyya, SuvanjanThe thermohydraulic characteristics of turbulent flow of air (Pr 0.7) through circular tube with short-length and full-length twisted-tape turbulators inserts have been studied experimentally. Also, heat transfer performance for different values of the twist ratio, tape thickness ratio and diameter ratio are investigated for Reynolds numbers within the range 6000–20,000. The full-length twisted tape enhances heat transfer more than those of short-length twisted tapes. Heat transfer and pressure drop tests were carried out in brass channels. The channel with twisted tape inserts specifies that the use of tapes augments heat transfer mostly, which is complemented by a greater friction penalty. The thermohydraulic performance of the problem under study has been assessed. It is observed that by using full-length twisted tape at constant pumping power, up to 27% heat duty rises in comparison with short-length twisted tape. Similarly, by using full-length twisted tape at heat duty, up to 33% pumping power increases in comparison with short-length twisted tape.