Symmetry

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31 pages, 6671 KiB

Open AccessArticle

First and Second Law Thermodynamic Analyses of Hybrid Nanofluid with Different Particle Shapes in a Microplate Heat Exchanger

by Kunal Sandip Garud, Seong-Guk Hwang, Taek-Kyu Lim, Namwon Kim and Moo-Yeon Lee

Symmetry 2021, 13(8), 1466; https://doi.org/10.3390/sym13081466 - 10 Aug 2021

Cited by 6 | Viewed by 1928

Abstract

The improvement in the quantitative and qualitative heat transfer performances of working fluids is trending research in the present time for heat transfer applications. In the present work, the first and second law analyses of a microplate heat exchanger with single-particle and hybrid [...] Read more.

The improvement in the quantitative and qualitative heat transfer performances of working fluids is trending research in the present time for heat transfer applications. In the present work, the first and second law analyses of a microplate heat exchanger with single-particle and hybrid nanofluids are conducted. The microplate heat exchanger with single-particle and hybrid nanofluids is analyzed using the computational fluid dynamics approach with symmetrical heat transfer and fluid flow analyses. The single-particle Al₂O₃ nanofluid and the hybrid Al₂O₃/Cu nanofluid are investigated for different nanoparticles shapes of sphere (Sp), oblate spheroid (OS), prolate spheroid (PS), blade (BL), platelet (PL), cylinder (CY) and brick (BR). The first law characteristics of NTU, effectiveness and performance index and the second characteristics of thermal, friction and total entropy generation rates and Bejan number are compared for Al₂O₃ and Al₂O₃/Cu nanofluids with considered different-shaped nanoparticles. The OS- and PL-shaped nanoparticles show superior and worse first and second law characteristics, respectively, for Al₂O₃ and Al₂O₃/Cu nanofluids. The hybrid nanofluid presents better first and second law characteristics compared to single-particle nanofluid for all nanoparticle shapes. The Al₂O₃/Cu nanofluid with OS-shaped nanoparticles depicts maximum values of performance index and Bejan number as 4.07 and 0.913, respectively. The first and second law characteristics of the best combination of the Al₂O₃/Cu nanofluid with OS-shaped nanoparticles are investigated for various volume fractions, different temperature and mass flow rate conditions of hot and cold fluids. The first and second law characteristics are optimum at higher hot fluid temperature, lower cold fluid temperature, lower hot and cold fluid mass flow rates. In addition, the first and second law characteristics have improved with increase in volume fraction. Full article

(This article belongs to the Special Issue Heat Transfer in Engineering)

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19 pages, 3986 KiB

Open AccessFeature PaperArticle

Numerical Investigations on Heat Transfer Characteristics of Single Particle and Hybrid Nanofluids in Uniformly Heated Tube

by Kunal Sandip Garud and Moo-Yeon Lee

Symmetry 2021, 13(5), 876; https://doi.org/10.3390/sym13050876 - 14 May 2021

Cited by 28 | Viewed by 3159

Abstract

In the present study, the heat transfer characteristics, namely, heat transfer coefficient, Nusselt number, pressure drop, friction factor and performance evaluation criteria are evaluated for water, Al₂O₃ and Al₂O₃/Cu nanofluids. The effects of Reynolds number, volume [...] Read more.

In the present study, the heat transfer characteristics, namely, heat transfer coefficient, Nusselt number, pressure drop, friction factor and performance evaluation criteria are evaluated for water, Al₂O₃ and Al₂O₃/Cu nanofluids. The effects of Reynolds number, volume fraction and composition of nanoparticles in hybrid nanofluid are analyzed for all heat transfer characteristics. The single particle and hybrid nanofluids are flowing through a plain straight tube which is symmetrically heated under uniform heat flux condition. The numerical model is validated for Nusselt number within 7.66% error and friction factor within 8.83% error with corresponding experimental results from the previous literature study. The thermophysical properties of hybrid nanofluid are superior to the single particle nanofluid and water. The heat transfer coefficient, Nusselt number and pressure drop show increasing trend with increase in the Reynolds number and volume fraction. The friction factor shows the parabolic trend, and the performance evaluation criteria shows small variations with change in Reynolds number. However, both friction factor and performance evaluation criteria have increased with increase in the volume fraction. The 2.0% Al₂O₃/Cu with equal composition of both nanoparticles (50/50%) have presented superior heat transfer characteristics among all working fluids. Further, the heat transfer characteristics of 2.0% Al₂O₃/Cu hybrid nanofluid are enhanced by changing the nanoparticle compositions. The performance evaluation criteria for 2.0% Al₂O₃, 2.0% Al₂O₃/Cu (50/50%), 2.0% Al₂O₃/Cu (75/25%) and 2.0% Al₂O₃/Cu (25/75%) are evaluated as 1.08, 1.11, 1.10 and 1.12, respectively. Full article

(This article belongs to the Special Issue Heat Transfer in Engineering)

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15 pages, 4040 KiB

Open AccessArticle

Energy Saving and Economic Evaluations of Exhaust Waste Heat Recovery Hot Water Supply System for Resort

by Nghia-Huu Nguyen, Dong-Yeon Lee, Kunal Sandip Garud and Moo-Yeon Lee

Symmetry 2021, 13(4), 624; https://doi.org/10.3390/sym13040624 - 08 Apr 2021

Cited by 1 | Viewed by 2238

Abstract

The objective of this study is to investigate the energy savings and economics of the hot water supply system for the luxury resort. The hot water was generated using the waste heat from the exhaust gas heat (EGH) of internal combustion engine (ICE) [...] Read more.

The objective of this study is to investigate the energy savings and economics of the hot water supply system for the luxury resort. The hot water was generated using the waste heat from the exhaust gas heat (EGH) of internal combustion engine (ICE) installed at the luxury resort. The capacity and characteristics of waste heat source, flow demand and supply system of hot water were surveyed, and data is collected from the real system. The new heat exchanger system which utilizes the EGH to produce the hot water is designed considering the dew point temperature and the back pressure of exhaust gas system. The results show that the proposed system could supply hot water at a temperature of 55 °C corresponding to the present resort demand of 6 m³/h using EGH of ICE at 20% load. The proposed system could achieve the saving of 400 L/day in diesel oil (DO) fuel consumption and the payback time of new system could be evaluated as 9 months. The proposed system could produce hot water of 14 m³/h at 25% of engine load and 29 m³/h at full engine load which are sufficient to satisfy the regular and maximum hot water demand of resort. The presented results show the capability of the proposed system to satisfy the current hot water demand of resort and suggest the larger potential to save energy by recovering EGH of ICE. The novelty of the present work involves detailed methodology to design heat exchangers and evaluate system economics for hot water supply system based on EGH of ICE. Full article

(This article belongs to the Special Issue Heat Transfer in Engineering)

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25 pages, 4845 KiB

Open AccessArticle

Experimental Study on Heating Performances of Integrated Battery and HVAC System with Serial and Parallel Circuits for Electric Vehicle

by Taek-Kyu Lim, Kunal Sandip Garud, Jae-Hyeong Seo, Moo-Yeon Lee and Dong-Yeon Lee

Symmetry 2021, 13(1), 93; https://doi.org/10.3390/sym13010093 - 07 Jan 2021

Cited by 2 | Viewed by 1955

Abstract

The objective of the present study is to conduct experiments for investigating heating performances of integrated system with serial and parallel circuits for battery and heating ventilation and air conditioning system (HVAC) of electric vehicles under various operating conditions. In addition, the artificial [...] Read more.

The objective of the present study is to conduct experiments for investigating heating performances of integrated system with serial and parallel circuits for battery and heating ventilation and air conditioning system (HVAC) of electric vehicles under various operating conditions. In addition, the artificial neural network (ANN) model is proposed to accurately predict the heating performances of integrated system with serial and parallel circuits for battery and HVAC. A test bench of integrated system with serial and parallel circuits has been developed for establishing the trade-off between battery heating and HVAC heating. The heating performances namely, battery out temperature, battery temperature rise rate, battery heating capacity, HVAC heating capacity and total heating capacity are evaluated experimentally for the integrated system with serial and parallel circuits. The behavior of various heating performances is evaluated under influence of flow rate and heater power. Battery out temperature reaches 40 °C within 10 min with rise rate of 2.17 °C/min for the integrated system with serial circuit and that within 20 min with rise rate of 1.22 °C/min for the integrated system with parallel circuit. Integrated system with serial circuit shows higher HVAC heating capacity than integrated system with parallel circuit which are 5726.33 W and 3869.15 W, respectively. ANN model with back-propagation algorithm, Levenberg-Marquardt training variant, Tan-sigmoidal transfer function and 20 hidden neurons presents the accurate prediction of heating performances of the integrated system with serial and parallel circuits for battery and HVAC. Full article

(This article belongs to the Special Issue Heat Transfer in Engineering)

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12 pages, 2896 KiB

Open AccessArticle

Experimental Performance Analysis of a Small Thermoelectric System Applicable to Real-Time PCR Devices

by Jae Hoon Chung and Sehoon Jeong

Symmetry 2020, 12(12), 1963; https://doi.org/10.3390/sym12121963 - 27 Nov 2020

Cited by 3 | Viewed by 1858

Abstract

At the International Space Station (ISS), not only observation of the space environment, but also biological and medical research under weightlessness has been conducted. The efficient use of energy from waste heat from the ISS away from the Earth is very important to [...] Read more.

At the International Space Station (ISS), not only observation of the space environment, but also biological and medical research under weightlessness has been conducted. The efficient use of energy from waste heat from the ISS away from the Earth is very important to the efficient operation of the ISS. To develop a thermoelectric module that can be used for real-time polymerase chain reaction (PCR) machinery used in biological and medical research, we simulated and evaluated the thermoelectric waste heat recovery system. Specifically, the thermoelectric module was attached to a stainless steel duct, and a hot air blower was faced with the duct inlet. The power of the thermoelectric system was measured by controlling the temperature of the hot air inlet. Additionally, the thermoelectric performance was evaluated according to the heat sink attached to the cold side of the thermoelectric module. Here, we also found the optimal heat exchange factors to improve the power and efficiency of the thermoelectric module. In this regard, it is expected that the thermoelectric module development and analysis study using waste heat will play an important role in the biological and medical research that is being conducted at ISS by developing a real-time PCR utilizing it. Full article

(This article belongs to the Special Issue Heat Transfer in Engineering)

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22 pages, 5910 KiB

Open AccessArticle

Numerical Investigations on Magnetohydrodynamic Pump Based Microchannel Cooling System for Heat Dissipating Element

by Jae-Hyeong Seo, Mahesh Suresh Patil, Satyam Panchal and Moo-Yeon Lee

Symmetry 2020, 12(10), 1713; https://doi.org/10.3390/sym12101713 - 16 Oct 2020

Cited by 9 | Viewed by 2848

Abstract

Numerical investigations are performed on the magnetohydrodynamic (MHD) pump-based microchannel cooling system for heat dissipating element. In the present study, the MHD pump performance is evaluated considering normal current density, magnetic flux density, volumetric Lorentz force, shear stress and pump flow velocity by [...] Read more.

Numerical investigations are performed on the magnetohydrodynamic (MHD) pump-based microchannel cooling system for heat dissipating element. In the present study, the MHD pump performance is evaluated considering normal current density, magnetic flux density, volumetric Lorentz force, shear stress and pump flow velocity by varying applied voltage and Hartmann number. It is found that for a low Hartmann number, the Lorentz force increases with an increase in applied voltage and Hartmann number. The velocity distribution along dimensionless width, the shear stress distribution along dimensionless width, the magnetic flux density along the dimensionless width and radial magnetic field distribution showed symmetrical behavior. The MHD pump-based microchannel cooling system performance is evaluated by considering the maximum temperature of the heat dissipating element, heat removal rate, efficiency, thermal field, flow field and Nusselt number. In addition, the influence of various nanofluids including Cu-water, TiO₂-water and Al₂O₃-water nanofluids on heat transfer performance of MHD pump-based microchannel is evaluated. As the applied voltage increased from 0.05 V to 0.35 V at Hartmann number 1.41, the heat removal rate increased by 39.5%. The results reveal that for low Hartmann number, average Nusselt number is increasing function of applied voltage and Hartmann number. At the Hartmann number value of 3.74 and applied voltage value of 0.35 V, average Nusselt numbers were 12.3% and 15.1% higher for Cu-water nanofluid compared to TiO₂-water and Al₂O₃-water nanofluids, respectively. The proposed magnetohydrodynamic microcooling system is effective without any moving part. Full article

(This article belongs to the Special Issue Heat Transfer in Engineering)

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22 pages, 14107 KiB

Open AccessArticle

Thermo-Hydraulic Performance Analysis on the Effects of Truncated Twisted Tape Inserts in a Tube Heat Exchanger

by Mehdi Ghalambaz, Ramin Mashayekhi, Hossein Arasteh, Hafiz Muhammad Ali, Pouyan Talebizadehsardari and Wahiba Yaïci

Symmetry 2020, 12(10), 1652; https://doi.org/10.3390/sym12101652 - 09 Oct 2020

Cited by 25 | Viewed by 3517

Abstract

This paper investigates the convective heat transfer in a heat exchanger equipped with twisted tape elements to examine effects of the twisted tape truncation percentage, pitch value, position and Reynolds number using 3D numerical simulation. A symmetric heat flux is applied around the [...] Read more.

This paper investigates the convective heat transfer in a heat exchanger equipped with twisted tape elements to examine effects of the twisted tape truncation percentage, pitch value, position and Reynolds number using 3D numerical simulation. A symmetric heat flux is applied around the tube as the studied heat exchanger. Based on the influences in both heat transfer enhancement and pressure drop, the performance evaluation criterion (PEC) is utilized. Inserting twisted tape elements and reducing the pitch value significantly augment the Nusselt number, friction coefficient and PEC number compared to the plain tube. For the best case with a Reynolds number of 1000, the average Nusselt number increases by almost 151%, which is the case of fully fitted twisted tape at a pitch value of L/4. Moreover, increasing the twisted tape truncation percentage reduces both heat transfer and pressure drop. Furthermore, the highest heat transfer rate is achieved when the truncated twisted tape is located at the entrance of the tube. Finally, it is concluded that for P = L, L/2, L/3 and L/4, the optimum cases from the viewpoint of energy conservation are twisted tapes with truncation percentages of 75, 50, 50 and 0%, in which the related PEC numbers at a Reynolds number of 1000 are almost equal to 1.08, 1.24, 1.4 and 1.76, respectively. Full article

(This article belongs to the Special Issue Heat Transfer in Engineering)

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22 pages, 3020 KiB

Open AccessArticle

A Study on Performance Characteristics of a Heat Pump System with High-Pressure Side Chiller for Light-Duty Commercial Electric Vehicles

by Moo-Yeon Lee, Kunal Sandip Garud, Han-Byeol Jeon and Ho-Seong Lee

Symmetry 2020, 12(8), 1237; https://doi.org/10.3390/sym12081237 - 27 Jul 2020

Cited by 4 | Viewed by 3363

Abstract

One of barriers for the present heat pump system’s application in an electric vehicle was decreased performance under cold ambient conditions due to the lack of evaporating heat source. In order to improve the heat pump’s performance, a high-pressure side chiller was additionally [...] Read more.

One of barriers for the present heat pump system’s application in an electric vehicle was decreased performance under cold ambient conditions due to the lack of evaporating heat source. In order to improve the heat pump’s performance, a high-pressure side chiller was additionally installed, and the tested heat pump system was modified with respect to refrigerant flow direction along with operating modes. In the present work, the performance characteristics of the heat pump system with a high-pressure side chiller for light-duty commercial electric vehicles were studied experimentally under hot and cold ambient conditions, reflecting real road driving. The high-pressure side chiller was located after the electric compressor so that the highest refrigerant temperature transferred the heat to the coolant. The controlled coolant with discharged refrigerant from the electric compressor was used to heat up the cabin, transferring heat to the inlet air like the internal combustion engine vehicle’s heating system, except with unused engine waste heat. In the cooling mode, for the exterior air temperature of 35 °C and interior air temperature of 25 °C, cooling performance along with the compressor speed showed that the system efficiency decreased by 16.4% on average, the cooling capacity increased by 8.0% on average and the compressor work increased by 27% on average. In heating mode, at the exterior and interior air temperature of −6.7 °C, compressor speed and coolant temperature variation with steady conditions were tested with respect to heating performance. In transient mode, to increase coolant temperature with a closed loop from −6.7 °C, tested system characteristics were studied along the compressor speed with respect to heating up the cabin. As the inlet air of the HVAC was maintained at −6.7 °C, even though the heat-up rate of the cabin room was a little slow, the cabin temperature reached 20 °C within 50 min and the temperature difference with the ambient air attained 28.7 °C. Full article

(This article belongs to the Special Issue Heat Transfer in Engineering)

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41 pages, 8058 KiB

Open AccessFeature PaperArticle

Power Generation, Efficiency and Thermal Stress of Thermoelectric Module with Leg Geometry, Material, Segmentation and Two-Stage Arrangement

by Moo-Yeon Lee, Jae-Hyeong Seo, Ho-Seong Lee and Kunal Sandip Garud

Symmetry 2020, 12(5), 786; https://doi.org/10.3390/sym12050786 - 08 May 2020

Cited by 32 | Viewed by 2836

Abstract

The objective of this study was to investigate the power generation, efficiency, and thermal stress of a thermoelectric module with leg geometry, material, segmentation, and two-stage arrangement. The effects of leg geometry, material, segmentation, and two-stage arrangement on maximum power, maximum efficiency, and [...] Read more.

The objective of this study was to investigate the power generation, efficiency, and thermal stress of a thermoelectric module with leg geometry, material, segmentation, and two-stage arrangement. The effects of leg geometry, material, segmentation, and two-stage arrangement on maximum power, maximum efficiency, and maximum stress under various temperature differences and voltage load conditions were investigated. The performance parameters of the thermoelectric module were evaluated based on a numerical approach using ANSYS 19.1 commercial software. An analytical approach based on theoretical equations of the thermoelectric module was used to verify the accuracy and reliability of the numerical approach. The numerically predicted values for maximum power and maximum efficiency of the thermoelectric module were validated as ±5% and those for the maximum thermal stress of the thermoelectric module as ±7% with the corresponding calculated theoretical values. In addition, the predicted values of maximum power and maximum stress of the thermoelectric module were validated as ±2% and ±5%, respectively, with studies reported by Ma et al. and Al-Merbati et al. Of all the combinations, the single stage segmented arrangement with cylindrical leg geometry and SiGe+Bi₂Te₃ material was suggested as the best combination with maximum power of 0.73 W, maximum efficiency of 13.2%, and maximum thermal stress of 0.694 GPa. Full article

(This article belongs to the Special Issue Heat Transfer in Engineering)

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30 pages, 7216 KiB

Open AccessArticle

Artificial Neural Network and Adaptive Neuro-Fuzzy Interface System Modelling to Predict Thermal Performances of Thermoelectric Generator for Waste Heat Recovery

by Kunal Sandip Garud, Jae-Hyeong Seo, Chong-Pyo Cho and Moo-Yeon Lee

Symmetry 2020, 12(2), 259; https://doi.org/10.3390/sym12020259 - 08 Feb 2020

Cited by 37 | Viewed by 2840

Abstract

The present study elaborates the suitability of the artificial neural network (ANN) and adaptive neuro-fuzzy interface system (ANFIS) to predict the thermal performances of the thermoelectric generator system for waste heat recovery. Six ANN models and seven ANFIS models are formulated by considering [...] Read more.

The present study elaborates the suitability of the artificial neural network (ANN) and adaptive neuro-fuzzy interface system (ANFIS) to predict the thermal performances of the thermoelectric generator system for waste heat recovery. Six ANN models and seven ANFIS models are formulated by considering hot gas temperatures and voltage load conditions as the inputs to predict current, power, and thermal efficiency of the thermoelectric generator system for waste heat recovery. The ANN model with the back-propagation algorithm, the Levenberg–Marquardt variant, Tan-Sigmoidal transfer function and 25 number of hidden neurons is found to be an optimum model to accurately predict current, power and thermal efficiency. For current, power and thermal efficiency, the ANFIS model with pi-5 or gauss-5-membership function is recommended as the optimum model when the prediction accuracy is important while the ANFIS model with gbell-3-membership function is suggested as the optimum model when the prediction cost plays a crucial role along with the prediction accuracy. The proposed optimal ANN and ANFIS models present higher prediction accuracy than the coupled numerical approach. Full article

(This article belongs to the Special Issue Heat Transfer in Engineering)

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23 pages, 6594 KiB

Open AccessArticle

Thermal Abuse Behavior of the LIR2450 Micro Coin Cell Battery Having Capacity of 120 mAh with Internal Short Circuit by Penetrating Element

by Moo-Yeon Lee, Namwon Kim, Jae-Hyeong Seo and Mahesh Suresh Patil

Symmetry 2020, 12(2), 246; https://doi.org/10.3390/sym12020246 - 05 Feb 2020

Cited by 7 | Viewed by 3850

Abstract

Internal short circuit in lithium-ion battery by penetrating element leads to exothermic behavior due to accumulated heat. In the present study, investigations are conducted on the thermal behavior of the LIR2450 micro coin cell haivng capacity of 120 mAh, with internal short circuit [...] Read more.

Internal short circuit in lithium-ion battery by penetrating element leads to exothermic behavior due to accumulated heat. In the present study, investigations are conducted on the thermal behavior of the LIR2450 micro coin cell haivng capacity of 120 mAh, with internal short circuit by penetrating element. The experimental coin cell discharge study was conducted and validated with numerical study within ±5.0%. The effect of penetrating element size, location of penetrating element, state of charge, discharge rate, short-circuit resistance, and heat transfer co-efficient on maximum coin cell temperature and heat generation rate are analyzed. The penetrating element diameters of 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, and 3.5 mm are considered. The effect of initial state of charge (SOC) is considered with 100%, 80%, 60%, and 40%. Three locations for penetrating element are considered with the center, the middle of the radius, and on the edge of the coin cell radius. The different discharge rates of 1C, 2C, 3C, and 4C are considered. The higher-penetrating element size of 3.5 mm with location at the center of the coin cell with 100% SOC showed maximum heat generation rate and maximum temperature of the coin cell. In addition, the optimum value of the dimensionless heat generation rate is obtained at dimensionless short-circuit resistance. The study provides comprehensive insights on the thermal behavior of the lithium-ion cell during thermal abuse condition with internal short circuit by penetrating element. Full article

(This article belongs to the Special Issue Heat Transfer in Engineering)

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