Faculty Publications
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Item Experimental and numerical investigation on conjugate effects in deep parallel microchannel using tio2 nanofluid for electronic cooling(Dalian University of Technology, 2018) Narendran, G.; Gnanasekaran, N.; Arumuga Perumal, D.A.The present study reports the numerical investigation of laminar forced convection based on TiO2 nanofluid in a rectangular copper microchannel surrounded by Aluminium block to examine the cooling effects for increased flow rates and particle concentration. The analysis involves the use of pure fluid and TiO2 nanofluid with the volume fractions of 0.01, 0.15, 0.20 and 0.25% for different flow rates. The study also examines the influence of conjugate heat transfer behavior of the microchannel using commercially available software FLUENT-15. © 2018 by the authors of the abstracts.Item A review on recent advances in microchannel heat sink configurations(Bentham Science Publishers, 2018) Narendran, G.; Gnanasekaran, N.; Arumuga Perumal, D.A.A qualitative observation has been undergone to review the various geometries of a microchannel that has been reported for the last two decades in literature majorly for the application of high power devices. Recent research on microchannel is more focused on numerical and experimental work with various configurations of the heat sink. In this paper, a comparative work on different flow geometries used in the microchannel and their influence on heat transfer and pressure drop is investigated with the brief representation of different working fluids used in microchannel heat sink for the purpose of electronic cooling and their associated performance characteristics with various examined parameters. Background: The microchannel cooling is an established cooling technique for high power electronic components which effectively enhances the performance of the high power devices. Objective: This article presents a general overview of microchannels with novel constructional bifurcations structures with related patents. Further, the influential parameter on thermal and flow characteristics with greater depth is also reviewed by authors. Methods: This review directs by presenting standard and benchmark investigation in the microchannel and different working parameters continued with recent studies. Further, it is addressed with the application of electronic cooling with latest patents using bifurcations and fractal microchannels. Result: The current situation of 3D cooling requires a robust cooling system to accommodate increased heat flux without compromising the packaging. Moreover, the recently developed patents also evolved with improved thermal load handling under constrained packaging. Conclusion: The advanced microchannel cooling with an optimized fluid handling system with effective packaging results in a highly effective heat dissipation system. © 2018 Bentham Science Publishers.Item Experimental analysis on exergy studies of flow through a minichannel using Tio2/Water nanofluids(Elsevier Ltd, 2018) Narendran, G.; Bhat, M.M.; Akshay, L.; Arumuga Perumal, D.A.The present study involves an experimental investigation on rectangular minichannel heat sink for processor cooling of a workstation. The thermal dissipation power of the corresponding system is 25 W. The heat sink is directly in contact to the processor core and subjected to continuous increase in heat flux to the sink depending on the system loading. Water and TiO2 nanofluid with volume fraction of 0.10%, 0.15%, 0.21% and 0.25% is used as the cooling fluid in the experiments with different volume flow rates with a pulsating pump in the range of 210–400 ml/min respectively. The observations were performed with the sink in both horizontal and vertical position in which heat sink is allowed to reach two different temperature limits of 40 °C and 55 °C above which it is subjected to cooling. The Increase in minichannel efficiency was noticed when flowrate increased from 210 ml/min to 280 ml/min with an increment of 53%, but it started to reduce when flow rate approaches 360 ml/min. The outlet exergy and pumping power increases as the flow rate increases to a limit. Furthermore, decrease in efficiency was noticed beyond flow rate of 360 ml/min and the highest outlet exergy was found at a flow rate of 360 ml/min for about 147.52 W. Additionally, exergy analysis is performed for pure fluid under different flow conditions were examined. Further the effect of nanofluid on pressure drop subjected to pulsating flow for varying volume concentrations is also presented. © 2018 Elsevier LtdItem Investigation on novel inertial minichannel to mitigate maldistribution induced high temperature zones(Elsevier Ltd, 2022) Narendran, G.; Gnanasekaran, G.Axial conduction in channels depends on inlet velocity and thermal conductivity of the working fluid. In the case of parallel channels, axial conduction depends on heat sink configuration and inlet velocity. That at increased flow rates, the parallel channel generates flow maldistribution and develops localized high temperature zones in the heat sink. Effective use of heat sink configuration to mitigate axial conduction is found in the literature; however, the axial conduction effects are not suppressed in the parallel channels. Henceforth, the present study provides experimental and numerical insight to evaluate the potential of ribs and inertial based spillway channels to overcome the above mentioned problems in parallel channels. Especially, four different heat sink concepts were designed using copper material; normal channel, ribbed channel, ribbed inclined, and ribbed lifted. In which normal channel is experimented with and used as a reference, while the remaining channel types were investigated numerically. The factors such as maldistribution, thermal resistance, and pressure drop are considered to evaluate the impact of the ribs on inlet velocity. The ribbed inclined channel was found to perform better than other types and developed a 33 % lower center channel velocity than the normal channel. The temperature near the exit of the ribbed inclined channel was observed to be more even and the entire width of the minichannel was maintained at 47 °C, this trend was not noticed using other configurations. © 2022 Elsevier LtdItem EFFECTS OF NANOREFRIGERANTS FOR REFRIGERATION SYSTEM: A REVIEW(Begell House Inc., 2023) Kumar, A.; Narendran, G.; Arumuga Perumal, A.P.In this article various nanorefrigerants have been critically reviewed towards the performance enhancement of the refrigeration system. Research has been more focused on the different techniques to prepare nanorefrigerants. This paper is an attempt to summarize all aspects of nanorefrigerants such as preparation, thermophysical properties, hydrodynamic study, boiling heat transfer, and performance of nanorefrigerants. It also discusses the effects of different nanoparticles on ther-mophysical properties. Nanorefrigerants are a special category of nanofluid, advanced nanotech-nology-based refrigerants that are stable mixtures of nanoparticles and base fluid, which improve thermophysical properties such as heat transfer and pressure drop and bring compactness to the system. This article presents an overview of improving thermal performance by using different nanoparticle blends with different base refrigerants. Further, influential parameters of nanopar-ticles and thermal performance are discussed. This paper also discusses the effects of different nanoparticles such as Al2O3, TiO2, CuO, carbon nanotubes (CNTs), etc., on thermophysical prop-erties. The present situation requires a robust system and refrigerants for required performance. Some refrigerants cannot be used directly. So, this paper deals with using nanorefrigerants for better system performance such as coefficient of performance (COP) enhancement, compressor work reduction, and energy efficiency. It is seen that the use of nanorefrigerants, or nanotechnology-based refrigerants, results in highly effective cooling and thus enhances the thermophysical properties of refrigeration systems. © 2023 by Begell House, Inc. www.begellhouse.com.Item Integrated microchannel cooling for densely packed electronic components using vanadium pentaoxide (V2O5)-xerogel nanoplatelets-based nanofluids(Springer Science and Business Media B.V., 2023) Narendran, G.; Gnanasekaran, N.; Arumuga Perumal, D.A.; Moolayadukkam, M.; Nagaraja, H.S.The present study reports the implementation of novel nanoplatelets-based vanadium pent oxide (V2O5)-xerogel for the application of conjugate cooling in densely packed electronic devices. An integrated heat sink is made up of copper with a channel width of 490 µm and is shrink-fitted into aluminium block that acts as a heat spreader. V2O5-xerogel is synthesized by melt quenching process and characterized based on field emission scanning electron microscope, transmission electron microscope, and X-ray diffraction to analyse the surface morphology of the particles. Studies related to the stability of the nanofluids for different concentrations are discussed in this paper. Furthermore, a study on the effect of pulsating flow in microchannel is performed for different flow rates. As a result, a maximum enhancement of 17% in heat transfer coefficient was observed for the concentration of 0.4 mass% with a flow rate of 200 mL min-1 compared to a pure fluid. Finally, the results reveal that the xerogel is a potential working fluid for heat transfer applications involving microscale devices. © 2023, Akadémiai Kiadó, Budapest, Hungary.Item Experimental investigation on additive manufactured single and curved double layered microchannel heat sink with nanofluids(Springer Science and Business Media Deutschland GmbH, 2023) Narendran, G.; Mallikarjuna, B.; Nagesha, B.K.; Gnanasekaran, N.For the latest high density compact devices, thermal management is crucial for their effective heat dissipation and system reliability. In literature, microchannel heat sink has been established as one of the advanced heat transfer techniques to fulfill the cooling demands of high power electronic applications. However, maldistribution in microchannels causes flow induced high temperature zones (FITZ) which reduces the electrical performance owing to electrical-thermal instability of the integrated chips. One way to mitigate the FITZ is by allowing more coolant inlets in these zones. In the current study, this is achieved by redesigning double layer microchannel heat sink (DMCHS) specific to the FITZ of I-type microchannel configuration using additive manufacturing (AM). Two AM microchannels were tested, one is a single layer microchannel heat sink (MCHS) and another one is a curved double layer microchannel (C-DMCHS). The curved channels were introduced in the bottom channels of C-DMCHS to mitigate FITZ compared to conventional DMCHS. AM microchannels are compared for Nusselt number and friction factor characteristics with the conventional straight channels, and heat treated AM microchannels. From experimental observation, Ti64 3D printed microchannel with Graphene oxide (GO-0.12%) nanofluid developed 75.4% more pressure drop than the Ti64 heat treated microchannel. The results additionally show that the C-DMCHS delivered 26.5% lower FITZ temperature than MCHS. © 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.Item A smart and sustainable energy approach by performing multi-objective optimization in a minichannel heat sink for waste heat recovery applications(Elsevier Ltd, 2023) Narendran, G.; Jadhav, P.H.; Gnanasekaran, N.Minichannel heat sink is widely used in waste heat recovery systems for their compactness and ability to recover heat effectively from high heat flux applications. However, the heat recovery efficiency is constrained by the flow configurations resulting in flow maldistribution. Numerous neural network combined evolutionary algorithms have been used to reduce pressure drop and flow maldistribution factors in the literature. But it is very challenging to assign appropriate weights to these parameters with no physical significance between them for optimization studies. To overcome this, TOPSIS-based optimization studies have been used in the current work to reduce the flow maldistribution factor (ϕ) and increase the Nusselt number (Nu) with ribs and inclined structures. Four Minichannel designs are studied to assess the channel heat recovery efficiency from small-scale incinerators using water and Graphene oxide (GO) nanofluid for three different volume fractions of GO-0.02%, GO-0.07%, and GO-0.12%. The motive is to determine an optimal nanofluid volume fraction and a suitable Minichannel configuration for the given heat flux. The TOPSIS method handles five criteria, including the combination of weightage for the maldistribution factor and Nusselt number. For criteria I ((ϕ)min: (Nu)max = 0.0:1.0) maximum weightage is given to heat transfer, the ribbed channel has gained a higher performance score for GO-0.07% nanofluid volume fraction. For criteria V ((ϕ)min: (Nu)max = 1.0:0.0) maximum weightage is given to maldistribution reduction, the ribbed inclined channel has gained with significantly higher performance score for all the studied nanofluid volume fractions. Further, the study is extended to determine the heat recovery efficiency, and it is found that with the increase in mass flow rate and nanofluid volume fraction, the heat recovery efficiency increases significantly. In particular, the maximum heat recovery efficiency of 66% was obtained for ribbed Minichannel using GO-0.12% nanofluid. © 2023 Elsevier LtdItem Analyzing the impact of nanofluid flow rate and thermal conductivity on response time in a compact heat spreader-integrated microchannel heat sink(Springer Science and Business Media B.V., 2024) Narendran, G.; Gnanasekaran, N.; Arumuga Perumal, D.In microchannel-based cooling devices, the response time exhibits distinctive variations owing to the heterogeneous integration of the heat source and the heat sink. These variations accompanied by flow maldistribution attributes to local temperature gradients are often referred to as flow-induced high-temperature zones and develop an uneven temperature distribution in microchannel heat sinks. To explore this phenomenon, we have designed an experimental setup featuring an in-house rectangular microchannel with an integrated heat spreader. In this study, we use a nanofluid comprised of graphene oxide (GO) and water as the working fluid, aiming to understand the thermo-hydrodynamics of the heat sink for various channel aspect ratios. The experimental results show that the heat wave propagation in the heat spreader is highly directional and influenced by the nanofluids flow rate and thermal conductivity. The study demonstrated that bulk fluid diffusion of GO nanofluid increased the temperature of the heat spreader by 30%. In the case of working fluid temperature, it increased by 35% for water and 52% for GO-0.12%. © Akadémiai Kiadó Zrt 2024.Item NUMERICAL INVESTIGATION ON MULTISTAGE BIFURCATED RECTANGULAR MICROCHANNEL WITH ASYMMETRICAL HOTSPOTS USING NANOFLUID(Begell House Inc., 2025) Narendran, G.; Kumar, A.; Arumuga Perumal, D.A.The numerical investigation of multistage-bifurcated microchannels with asymmetric hotspots using TiO2 nanofluid has been studied. The latest multi-core processors generate an asymmetrical heat flux described as hotpots. In literature, compact heat sinks are used to mitigate hotspots to achieve the cooling demands in industrial applications The temperature in the microchannel heat sink increases along the fluid direction, resulting in higher temperatures at the outlet. One way is to introduce bifurcations near the microchannel exit to reduce the heatsink bottom temperature near the outlet. The effective use of bifurcations for asymmetric hotspot application with nanofluids has not been dealt with much. Subsequently, the study presents a numerical analysis in a multistage bifurcated microchannel with asymmetric hotspots. The analysis provides profound insight into hotspot influences over bifurcation stages and working fluid flow rate. It was found critically that the effect of bifurcations was more criti-cal on flow rate than to the asymmetric hotspot and nanofluids. © 2025 by Begell House, Inc.