Article
Engineering, Chemical
Mehdi Bahiraei, Nima Mazaheri
Summary: The study focuses on the second law attributes of a counter-flow spiral heat exchanger with an Al2O3-H2O nanofluid, showing that dispersing more nanoparticles can reduce total entropy generation while increasing thermal entropy generation. Overall exergy destruction in the heat exchanger decreases significantly with increasing volume fraction, but tends to increase with flow rate increment. The second law efficiency of the heat exchanger is consistently high, with a minimum value greater than 0.84 and increasing with higher volume fraction or flow rate.
ADVANCED POWDER TECHNOLOGY
(2021)
Article
Engineering, Environmental
Fuyi Cui, Fuhai Liu, Yijie Tong, Shifeng Wang, Weigang Guo, Tianlong Han, Xudong Qiu
Summary: This study aims to enhance and compare the thermal efficiency of a solar collector by using water, Fe3O4 nanofluid, and Fe3O4/MWCNT hybrid nanofluid as working fluids. The results indicated that using Fe3O4/MWCNT hybrid nanofluids significantly improved the efficiency of the solar collector.
PROCESS SAFETY AND ENVIRONMENTAL PROTECTION
(2022)
Article
Engineering, Environmental
Fuyi Cui, Fuhai Liu, Yijie Tong, Shifeng Wang, Weigang Guo, Tianlong Han, Xudong Qiu
Summary: The consistent misuse of fossil fuels has led to increasing environmental pollution in many countries. Developing and utilizing solar energy is necessary. This study aimed to improve and compare the thermal efficiency of a solar collector using water, Fe3O4 nanofluid, and Fe3O4/MWCNT hybrid nanofluid as working fluids. The results showed that the evacuated tube solar collector achieved the highest efficiency when the Fe3O4/MWCNT hybrid nanofluid (mixing ratio 1/4) was used as the working fluid.
PROCESS SAFETY AND ENVIRONMENTAL PROTECTION
(2022)
Article
Thermodynamics
Toygun Dagdevir, Veysel Ozceyhan
Summary: This study applied thermohydraulic performance and second law analysis to compare the performance of a heat exchanger tube with straight tape (RIST) and twisted tape (RITT) under constant heat flux and turbulent flow conditions using water/CuO nanofluid. The results showed that although RITT cases had better thermal performance, they did not significantly affect the second law efficiency due to greater frictional losses. However, the use of nanofluid significantly increased the second law efficiency.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2022)
Article
Thermodynamics
Toygun Dagdevir, Veysel Ozceyhan
Summary: This study applied thermohydraulic performance and second law analysis using water/CuO nanofluid in a heat exchanger tube. Results showed that RITT cases outperformed RIST cases in terms of thermal performance, and the use of nanofluid had a significant impact on increasing second law efficiency.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2022)
Article
Engineering, Chemical
Nima Mazaheri, Mehdi Bahiraei, Shabnam Razi
Summary: This study conducts a 3D two-phase analysis to evaluate the second law features of a counter-flow microchannel heat exchanger operating with a nanofluid. The results show that suspending more nanoparticles can reduce the thermal irreversibility of the nanofluid, but it increases the thermal irreversibility of the cold water. The volume fraction of the nanofluid has different effects on the exergy destruction and entropy generation at different flow rates.
Article
Thermodynamics
Mohammad Jamshidmofid, Mohammad Olfati, Ahmad Arabkoohsar, Abbas Abbassi
Summary: For the first time, this research investigates the influence of wavy orientations on entropy generation and exergy destruction in wavy microchannels with different types of aqueous nanofluids. Numerical simulations were conducted with two types of wavy microchannels (Left-Right and Up-Down) using silver, aluminum oxide, and hybrid silver-aluminum oxide nanofluids at different concentrations. The results show that the Left-Right wavy microchannel exhibits 20% lower exergy destruction compared to the Up-Down one, and utilizing nanofluids reduces exergy destruction, with the largest reduction observed in the case of silver nanofluid. Additionally, nanofluids enhance the effectiveness number while increased pumping power decreases it.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2023)
Article
Thermodynamics
Luis Silva-Llanca, Sebastian Inostroza-Lagos
Summary: Vertical Axis Wind Turbines have emerged as a viable complement to conventional wind turbines, being more suitable for urban and remote areas. By utilizing the Second Law of Thermodynamics, a better understanding of fluid dynamics phenomena can be achieved, with the Second Law Efficiency maximizing at an intermediate Tip Speed Ratio for more efficient power generation.
ENERGY CONVERSION AND MANAGEMENT
(2021)
Article
Green & Sustainable Science & Technology
Kapil Chaudhri, J. L. Bhagoria, Vikash Kumar
Summary: In this study, the heat transfer in roughened solar air ducts was enhanced using transverse wedge shaped roughened absorbers, which provided ambient cool air to the absorber plate surface and roughness elements on the heated plate, thereby improving the heat transfer coefficient.
Article
Materials Science, Multidisciplinary
L. Syam Sundar, Bobby Mathew, Ahmed Sefelnasr, Mohsen Sherif, Antonio C. M. Sousa
Summary: Experimental study on the second law efficiency of a transition flow in a tube containing 40:60% weight ratio of propylene glycol and water mixture based nanodiamond nanofluid showed improvements in heat transfer, friction factor, pumping power, and thermal performance as the particle concentration and Reynolds number increased. Compared to the base fluid, the nanofluid exhibited significant enhancements in heat transfer coefficient, Nusselt number, pressure drop, pumping power, friction factor, and thermal performance factor, along with reduced thermal entropy generation.
DIAMOND AND RELATED MATERIALS
(2021)
Article
Thermodynamics
Saeed Aghakhani, Ahmad Hajatzadeh Pordanjani, Masoud Afrand, Ayoob Khosravi Farsani, Nader Karimi, Mohsen Sharifpur
Summary: This paper presents a thermodynamic analysis of a mini circular heatsink, investigating different types of heatsinks and their performance. The results show that copper heatsinks have better cooling performance than aluminum heatsinks. Additionally, the study found that the addition of nanoparticles to the working fluid has a minimal impact on the thermodynamic performance of the system. Increasing the Reynolds number of the fluid flow reduces the exergy losses and improves the first and second law efficiencies.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2023)
Article
Thermodynamics
A. M. Alklaibi, Kotturu V. V. Chandra Mouli, L. Syam Sundar
Summary: The performance of a shell and helically coil heat exchanger using a 60% water and 40% ethylene glycol mixture based Fe3O4 nanofluid as coolant was experimentally investigated. Fe3O4 nanoparticles with an average particle size of 11.42 nm were synthesized using chemical co-precipitation. Correlations for the thermo-physical properties of the nanofluid were developed. The exergy efficiency of the heat exchanger can be increased by 21% using 1.0 vol% of nanofluid, but further increase in concentration shows limited improvement in heat transfer effectiveness. The study recommends not exceeding 1.0 vol% volume concentration of Fe3O4/60:40 % W + EG nanofluid due to cost and complexity considerations.
THERMAL SCIENCE AND ENGINEERING PROGRESS
(2023)
Article
Energy & Fuels
Mohammed Alktranee, Mohammed Ahmed Shehab, Zoltan Nemeth, Peter Bencs, Klara Hernadi
Summary: Recently, the use of nanofluids as coolants for photovoltaic modules has gained attention due to the ability to enhance the performance of the modules. This study investigates the use of zirconium oxide nanofluid at different volume concentrations as a coolant for reducing the temperature of photovoltaic cells. The results show that using zirconium oxide nanofluid at a volume concentration of 0.0275% in deionized water effectively reduces the temperature of the PV module and improves system energy and exergy efficiency.
Article
Multidisciplinary Sciences
Morteza Mohammadi
Summary: In this study, the flow features and heat transfer characteristics of a finned and finless double-tube counter flow heat exchanger were analyzed numerically at a wide range of Reynolds numbers. Different fin configurations and TiO2 nanofluid with varying nanoparticle concentrations were used to evaluate their effects on nanofluid Nusselt number, friction factor, and thermal performance index. The thickness of the embedded fins was found to have a significant impact on the thermohydrodynamical performance of the heat exchanger. The results showed that fins with larger thicknesses (≥10 mm) exhibited better thermal performance compared to fins with smaller thicknesses (t = 1 mm).
ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING
(2023)
Article
Thermodynamics
Kashif Irshad, Nazrul Islam, Md Hasan Zahir, Amjad Ali Pasha, Ahmed Farouk AbdelGawad
Summary: In this study, a new type of nanofluid based on multi-walled carbon nanotube and cupric oxide was developed as a promising heat transfer fluid. The nanocomposite significantly increased the thermal conductivity but also enhanced the viscosity of the nanofluid. Numerical analysis showed that the formulated nanofluid exhibited good heat transfer performance.
CASE STUDIES IN THERMAL ENGINEERING
(2022)
Article
Engineering, Chemical
Mehdi Bahiraei, Nima Mazaheri, Siavash Hosseini
Article
Engineering, Chemical
Mehdi Bahiraei, Nima Mazaheri, Mohammad Rasool Daneshyar
Article
Engineering, Chemical
Mehdi Bahiraei, Nima Mazaheri
Summary: The study focuses on the second law attributes of a counter-flow spiral heat exchanger with an Al2O3-H2O nanofluid, showing that dispersing more nanoparticles can reduce total entropy generation while increasing thermal entropy generation. Overall exergy destruction in the heat exchanger decreases significantly with increasing volume fraction, but tends to increase with flow rate increment. The second law efficiency of the heat exchanger is consistently high, with a minimum value greater than 0.84 and increasing with higher volume fraction or flow rate.
ADVANCED POWDER TECHNOLOGY
(2021)
Article
Thermodynamics
Mehdi Bahiraei, Nima Mazaheri, Mohammad Rasool Daneshyar
Summary: The study found that adding nanoparticles during the flow of a silver-water nanofluid has a significant positive effect on enhancing heat dissipation performance. Additionally, the heat transfer coefficient increases significantly with an increase in fin density.
APPLIED THERMAL ENGINEERING
(2021)
Article
Engineering, Chemical
Nima Mazaheri, Mehdi Bahiraei, Shabnam Razi
Summary: The study shows that using nanofluid in a four-layer microchannel heat exchanger can significantly enhance the overall heat transfer coefficient without increasing pressure drop. An increase in channel number leads to a more severe disruption in the thermal boundary layer, resulting in improved heat transfer performance.
Article
Energy & Fuels
Mehdi Bahiraei, Nima Mazaheri, Maryam Hanooni
Summary: By incorporating innovative crimped-spiral ribs and nanofluid into a triple-tube heat exchanger, this research significantly improved heat transfer efficiency and thermal performance. The introduction of crimped-spiral ribs enhanced swirl flow and boundary layer destruction, leading to increased heat transfer capability. Additionally, nanofluid showed excellent performance even at low volume fractions.
CHEMICAL ENGINEERING AND PROCESSING-PROCESS INTENSIFICATION
(2021)
Article
Thermodynamics
Mehdi Bahiraei, Nima Mazaheri
Summary: This study compares the efficiency of a novel spiral liquid block with other types of liquid blocks for cooling electronic processors. The spiral liquid block demonstrates superior cooling efficiency under constant pumping power. The addition of biologically produced nanofluid with graphene nanoplatelets in the liquid block can significantly reduce CPU surface temperature and thermal resistance.
Article
Engineering, Chemical
Mehdi Bahiraei, Loke Kok Foong, Siavash Hosseini, Nima Mazaheri
Summary: In this study, eight optimizer methods were combined with a perceptron neural network to predict the heat transfer rate of a ribbed triple-tube heat exchanger with graphene nanoplatelets-based nanofluid. Among the optimization techniques used, the ALO algorithm showed the best performance in estimating the output, achieving the best results with a population size of 350.
Article
Energy & Fuels
Mehdi Bahiraei, Nima Mazaheri
Summary: The study found that the spiral heat sink has smaller irreversibility and reasonable pressure drop intensification compared to the serpentine heat sink, which can effectively improve heat transfer efficiency. In the nanofluid, higher particle concentration can reduce temperature gradients and decrease thermal irreversibility.
CHEMICAL ENGINEERING AND PROCESSING-PROCESS INTENSIFICATION
(2021)
Article
Engineering, Multidisciplinary
Mehdi Bahiraei, Loke Kok Foong, Siavash Hosseini, Nima Mazaheri
Summary: In this study, four nature-inspired optimizers were combined with a neural network to predict the overall heat transfer coefficient of a ribbed triple-tube heat exchanger. The BBO algorithm showed the highest accuracy and performance, while the ACO algorithm had the lowest computational time.
Article
Energy & Fuels
Nima Mazaheri, Mehdi Bahiraei
Summary: The study investigated the energy, exergy, and hydrodynamic characteristics of using boehmite alumina nanofluid in a spiral heat exchanger with five different nanoparticle shapes. It was found that higher volume fractions of nanofluid enhanced heat exchange amount, overall heat transfer coefficient (U), and effectiveness. Different nanoparticle shapes had varying effects on thermal efficiency and energy efficiency, with platelet-shaped nanoparticles performing best at constant Re and oblate spheroid-shaped nanoparticles being recommended for energy efficiency perspective.
CHEMICAL ENGINEERING AND PROCESSING-PROCESS INTENSIFICATION
(2021)
Article
Engineering, Chemical
Nima Mazaheri, Mehdi Bahiraei, Shabnam Razi
Summary: This study conducts a 3D two-phase analysis to evaluate the second law features of a counter-flow microchannel heat exchanger operating with a nanofluid. The results show that suspending more nanoparticles can reduce the thermal irreversibility of the nanofluid, but it increases the thermal irreversibility of the cold water. The volume fraction of the nanofluid has different effects on the exergy destruction and entropy generation at different flow rates.
Article
Green & Sustainable Science & Technology
Mehdi Bahiraei, Nima Mazaheri, Maryam Hanooni
Summary: This research focuses on studying the performance of a triple pipe heat exchanger (TPHE) with an innovative crimped-spiral rib and an alumina-water nanofluid from the perspective of the second law. The results show that using the crimped-spiral rib effectively reduces the thermal entropy generation of the nanofluid and improves the energy efficiency.
SUSTAINABLE ENERGY TECHNOLOGIES AND ASSESSMENTS
(2022)
Article
Thermodynamics
Nima Mazaheri, Shoaib Khanmohammadi, Mehdi Bahiraei, Zafar Said
Summary: This study investigates the impact of alumina-water nanofluid on the thermally generated entropy in a ribbed passage. The results show that the nanofluid can significantly reduce the thermal entropy, with the triangular-shaped rib demonstrating better performance.
THERMAL SCIENCE AND ENGINEERING PROGRESS
(2022)
Article
Thermodynamics
Mahsa Taghavi, Swapnil Sharma, Vemuri Balakotaiah
Summary: This study investigates the natural convection effects in the insulation layers of spherical storage tanks and their impact on the tanks' performance. The permeability and Rayleigh number of the insulation material are considered as key factors. The results show that as the Rayleigh number increases, new convective cells emerge and cause the cold boundary to approach the external hot boundary. In the case of large temperature differences, multiple solutions may coexist.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Jinyang Xu, Fangjun Hong, Chaoyang Zhang
Summary: This study introduces a self-induced jet impingement device for enhancing pool boiling performance in high power electronic cooling. Through visualization and parametric investigations, the effects of this device on pool boiling performance are studied, revealing the promotion of additional liquid supply and vapor exhausting. The flow rate of the liquid jet is found to positively impact boiling performance.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Wenchao Ke, Yuan Liu, Fissha Biruke Teshome, Zhi Zeng
Summary: Underwater wet laser welding (UWLW) is a promising and labor-saving repair technique. A thermal multi-phase flow model was developed to study the heat transfer, fluid dynamics, and phase transitions during UWLW. The results show that UWLW creates a water keyhole, making the welding environment similar to in air laser welding.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Xingrong Lian, Lin Tian, Zengyao Li, Xinpeng Zhao
Summary: This study investigates the heat transfer mechanisms in natural fiber-derived porous structures and finds that thermal radiation has a significant impact on the thermal conductivity in low-density regions, while natural convection rarely occurs. Insulation materials derived from micron-sized natural fibers can achieve minimum thermal conductivity at specific densities. Strategies to lower the thermal conductivity include increasing porosity and incorporating nanoscale pores using nanosize fibers.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Yasir A. Malik, Kilian Koebschall, Stephan Bansmer, Cameron Tropea, Jeanette Hussong, Philippe Villedieu
Summary: Ice crystal icing is a significant hazard in aviation, and accurate modeling of sticking efficiency is essential. In this study, icing wind tunnel experiments were conducted to quantify the volumetric liquid water fraction, sticking efficiency, and maximum thickness of ice layers. Two measurement techniques, calorimetry and capacitive measurements, were used to measure the liquid water content and distribution in the ice layers. The experiments showed that increasing wet bulb temperatures and substrate heat flux significantly increased sticking efficiency and maximum ice layer thickness.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Jinqi Hu, Tongtong Geng, Kun Wang, Yuanhong Fan, Chunhua Min, Hsien Chin Su
Summary: This study experimentally examined the heat dissipation of vibrating fans and demonstrated its inherent mechanism through numerical simulation. The results showed that the flow fields induced by the vibrating blades exhibited pulsating features and formed large-scale and small-scale vortical structures, significantly improving heat dissipation. The study also identified the impacts of different blade structures and developed a trapezoidal-folding blade, which effectively reduced the maximum temperature of the heat source and alleviated high-temperature failure crisis.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Dan-Dan Su, Xiao-Bin Li, Hong-Na Zhang, Feng-Chen Li
Summary: The boiling heat transfer of low-boiling-point working fluid is a common heat dissipation technology in electronic equipment cooling. This study analyzed the interfacial boiling behavior of R134a under different conditions and found that factors such as the initial thickness of the liquid film, solid-liquid interaction force, and initial temperature significantly affect the boiling mode and thermal resistance.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Jinyi Wu, Dongke Sun, Wei Chen, Zhenhua Chai
Summary: A unified lattice Boltzmann-phase field scheme is proposed to simulate dendrite growth of binary alloys in the presence of melt convection. The effects of various factors on the growth are investigated numerically, and the model is validated through comparisons and examinations.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Shaokun Ge, Ya Ni, Fubao Zhou, Wangzhaonan Shen, Jia Li, Fengqi Guo, Bobo Shi
Summary: This study investigated the temperature distribution of main cables in a suspension bridge during fire scenarios and proposed a prediction model for the maximum temperature of cables in different lane fires. The results showed that vehicle fires in the emergency lane posed a greater thermal threat to the cables.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Shuang-Ying Wu, Shi-Yao Zhou, Lan Xiao, Jia Luo
Summary: This paper investigates the two-phase flow and heat transfer characteristics of low-velocity jet impacting on a cylindrical surface. The study reveals that the heat transfer regimes are non-phase transition and nucleate boiling with the increase of heat transfer rate. The effects of jet impact height and outlet velocity on local surface temperatures are pronounced at the non-phase transition stage. The growth rates of heat transfer rate and liquid loss rate increase significantly from the non-phase transition to nucleate boiling stage.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Emad Hasani Malekshah, Wlodzimierz Wlodzimierz, Miros law Majkut
Summary: Cavitation has significant practical importance and can be controlled by air injection. This study investigates the natural to ventilated cavitation process around a hydrofoil through numerical and experimental methods. The results show that the location and rate of air injection have a meaningful impact on the characteristics of cavitation.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Feriel Yahiat, Pascale Bouvier, Antoine Beauvillier, Serge Russeil, Christophe Andre, Daniel Bougeard
Summary: This study explores the enhancement of mixing performance in laminar flow equipment by investigating the generation of chaotic advection using wall deformations in annular geometries. The findings demonstrate that the combined geometry can achieve perfect mixing at various Reynolds numbers.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Hui He, Ning Lyu, Caihua Liang, Feng Wang, Xiaosong Zhang
Summary: This study investigates the condensation, frosting, and defrosting processes on superhydrophobic surfaces with millimeter-scale structures. The results reveal that the structures can influence the growth and removal of frost crystals, with the bottom grooves creating a frost-free zone and conical edges promoting higher frost crystal heights. Two effective methods for defrosting are observed: hand-lifting the groove and airfoil retraction contraction on protruding structures. This research provides valuable insights into frost formation and defrosting on millimeter-structured superhydrophobic surfaces, with potential applications in anti-frost engineering.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Thiwanka Arepolage, Christophe Verdy, Thibaut Sylvestre, Aymeric Leray, Sebastien Euphrasie
Summary: This study developed two thermal concentrators, one with a 2D design of uniform thickness and another with a 3D design, using the coordinate transformation technique and metamaterials. By structuring the thermal conductor, the desired local density-heat capacity product and anisotropic thermal conductivities were achieved. The homogenized thermal conductivities were obtained from finite element simulations and cylindrical symmetry consideration. A 3D concentrator was fabricated using 3D metal printing and characterized using a thermal camera. Compared to devices that solely consider anisotropic conductivities, the time evolution characteristics of the metadevice designed with coordinate transformation were closer to those of an ideal concentrator.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Liangyuan Cheng, Qingyang Wang, Jinliang Xu
Summary: In this study, we investigated the supercritical heat transfer of CO2 in a horizontal tube with a diameter of 10.0 mm, covering a wide range of pressures, mass fluxes, and heat fluxes. The study revealed a non-monotonic increase in wall temperatures along the flow direction and observed both positive and negative wall temperature differences between the bottom and top tube. The findings were explained by the thermal conduction in the solid wall interacting with the stratified-wavy flow in the tube.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)