Performance Evaluation Criteria in Heat Transfer Enhancement

Saha, Sujoy Kumar; Ranjan, Hrishiraj; Emani, Madhu Sruthi; Bharti, Anand Kumar

doi:10.1007/978-3-030-20758-8

Cited by 10 publications

(6 citation statements)

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“…In our study, we have used objective functions and constraints such as (a) same inlet diameter of the device/smooth pipe; (b) same length of the device/smooth pipe; and (c) same pumping power required for the device/smooth pipe operation for reduced flow rates. The derivation for the arrived formula can be referenced in Webb and Kim and Saha et al The formula has been commonly used for evaluation of reactor designs where both heat transfer and pumping power are to be considered. ,, where Nu is the Nusselt number and f is the frictional factor.…”

Section: Computational Modelmentioning

confidence: 99%

Passive Mixer cum Reactor Using Threaded Inserts: Investigations of Flow, Mixing, and Heat Transfer Characteristics

Khalde

Ramanan

Sangwai

et al. 2019

Ind. Eng. Chem. Res.

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Significant efforts have been and are being spent on developing intensified tubular reactors for continuous manufacturing of fine and specialty chemicals. In this work, we have proposed a new design of passive mixer-cum-reactor for process intensification and development of continuous processes. The mixer/reactor consists of threaded inserts with cone-shaped ends, placed concentrically in the tube such that fluid flows through the annular region between the inserts and the tube. The proposed design is easy to fabricate, maintain, and overcomes the limitations of scale up/scale down compared to most of the commercial passive mixers. The split and recombine of flow around inserts, the swirling effect generated by threads, change in the swirl direction due to change in the direction of screw threads, and pinching effect/expansion at the cone-cone shaped ends realize desired enhancements in mixing and heat transfer. A detailed computational study has been carried out on the mixer-cum-reactor to characterize flow, mixing and heat transfer at different operating conditions using a verified and validated CFD model. Various designs and configurations of threaded inserts were considered: 5-channel, 7-channel and 9-channel, smooth surface (no threading) and smooth surface-extended rear end inserts. The flow, mixing and heat transfer were characterized over the Reynolds number range of 100 to 1600. Structure of the generated swirling flow, effect of pinching/expansion, direction reversal of flow, tracer fraction, temperature and path lines were investigated systematically to gain new insights. Threaded inserts could achieve excellent mixing (>99 % of mixing intensity) and heat transfer (7 times smooth inserts and 20 times without inserts). The presented results will provide a sound basis for selecting appropriate threaded inserts for intensifying mixing and heat transfer in tubular reactors. The work also provides a useful starting point for further work on multiphase flows in a tubular reactor with threaded inserts.

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Section: Computational Modelmentioning

confidence: 99%

Passive Mixer cum Reactor Using Threaded Inserts: Investigations of Flow, Mixing, and Heat Transfer Characteristics

Khalde

Ramanan

Sangwai

et al. 2019

Ind. Eng. Chem. Res.

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“…There are two basic cooling methods to control the temperature generated during the charge/discharge cycle of batteries: active (air cooling and liquid cooling) and passive (PCM and heat pipe) [7]. Active methods require some external power input to achieve an advancement in the heat transfer rate [8]. The equipment required for this method increases the cost, weight, and complexity of the system.…”

Section: Introductionmentioning

confidence: 99%

Combined Utilization of Cylinder and Different Shaped Alumina Nanoparticles in the Base Fluid for the Effective Cooling System Design of Lithium-Ion Battery Packs

2023

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It is important to consider the thermal management of lithium-ion batteries to overcome their limitations in usage and improve their performance and life cycles. In this study, a novel cooling system for the thermal management of lithium-ion battery packs is proposed by using an inner cylinder in the cooling channel and different-shaped nanoparticles in the base fluid, which is used as the cooling medium. The performance improvements in a 20 Ah capacity battery are compared by using a water–boehmite alumina (AlOOH) nanofluid, considering cylinder-, brick-, and blade-shaped nanoparticles up to a solid volume fraction of 2%. The numerical analysis is conducted using the finite element method, and Reynolds numbers between 100 and 600 are considered. When the efficacy of the coolants utilized is compared, it is apparent that as the Reynolds number increases, both cooling media decrease the highest temperature and homogenize the temperatures in the battery. The utilization of the cylinder in the mini-channel results in a 2 °C temperature drop at Re = 600 as compared to the flat channel. A boehmite alumina nanofluid with a 2% volume fraction reduces the maximum temperature by 5.1% at Re = 200. When the shape effect of the nanofluid is examined, it is noted that the cylinder-shaped particle improves the temperature by 4.93% as compared to blade-shaped nanoparticles and 7.32% as compared to brick-shaped nanoparticles. Thus, the combined utilization of a nanofluid containing cylindrical-shaped nanoparticles as the cooling medium and a cylinder in the mini-channel of a battery thermal management system provides an effective cooling system for the thermal management of the battery pack. The outcomes of this work are helpful for further system design and optimization studies related to battery thermal management.

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“…Thus, optimization of channel cross-sectional geometry is employed in this work. No viscous dissipation is considered, and Performance evaluation criteria (PEC) are used in order to determine heat transfer enhancement under defined constraints [7,10], and are sometimes coupled to second-law analyses [11]. This work complements other investigations by the same authors which dealt with other micro-geometries or boundary conditions [12][13][14], considered viscous dissipation [15,16] or electro-osmotic effects [17][18][19].…”

Section: Introductionmentioning

confidence: 99%

“…The velocity and temperature fields are computed to obtain the Poiseuille and Nusselt numbers, which are in turn employed in the objective functions of the PEC, following the same approach as [9][10][11][12][13], in order to estimate the influence of the geometry of the cross-section. Results for a selection of PEC are shown and commented.…”

Section: Introductionmentioning

confidence: 99%

Performance Evaluation Criteria for Triangular Microchannels with Smoothed Corners

Suzzi

Lorenzini

2022

J. Phys.: Conf. Ser.

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The manufacturing capabilities available today for microchannels make it possible to produce in a comparatively easy, quick and cheap way several cross-sections, possibly allowing modifications of the macro-geometry. Another way is smoothing the corners of polygona cross-sections: this eliminates low-gradient areas and increases transport phenomena, i.e. frictional losses and heat transfer. Several ways of assessing the relative performance of the new shape in comparison to the original have been suggested over the years, among which are Performance Evaluation Criteria (PEC), as proposed by Bergles and Webb. PEC are based on a first-law analysis and aim at extremising the thermal power, heat exchange area, inlet temperature difference or pumping power under varying constraints. In this work equilateral triangular microchannels with uniform wall temperature are considered, through which a liquid flows in fully-developed, steady laminar regime. The cross-sectional area has its corners progressively rounded, and the velocity and temperature profiles are determined, in order to compute the Poiseuille, Nusselt and Stanton numbers, which are then employed in computing the objective functions for some PEC.

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Performance Evaluation Criteria in Heat Transfer Enhancement

Cited by 10 publications

References 0 publications

Passive Mixer cum Reactor Using Threaded Inserts: Investigations of Flow, Mixing, and Heat Transfer Characteristics

Passive Mixer cum Reactor Using Threaded Inserts: Investigations of Flow, Mixing, and Heat Transfer Characteristics

Combined Utilization of Cylinder and Different Shaped Alumina Nanoparticles in the Base Fluid for the Effective Cooling System Design of Lithium-Ion Battery Packs

Performance Evaluation Criteria for Triangular Microchannels with Smoothed Corners

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