Article
Thermodynamics
L. Syam Sundar, Feroz Shaik, K. V. Sharma, V. Punnaiah, Antonio C. M. Sousa
Summary: This study experimentally investigates the effects of nanofluids and longitudinal strip inserts on Nusselt number, friction factor, exergy efficiency, and thermal entropy generation in a circulating conduit. The results show that hybrid nanofluids with longitudinal strip inserts can significantly enhance heat transfer, reduce friction factor and thermal entropy generation.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2022)
Article
Energy & Fuels
Syed Jafer Kutbudeen, Kamaraj Logesh, Arulprakasajothi Mahalingam, I Vinoth Kanna
Summary: This study demonstrates the effectiveness of solar collectors using Al2O3/deionized water nanofluids and conical strip inserts, showing higher heat transfer enhancement at a 0.35% volume concentration. The addition of conical inserts further improves heat transfer efficiency.
ENERGY SOURCES PART A-RECOVERY UTILIZATION AND ENVIRONMENTAL EFFECTS
(2021)
Article
Chemistry, Multidisciplinary
Nabeel Abed, Imran Afgan, Hector Iacovides, Andrea Cioncolini, Ilyas Khurshid, Adel Nasser
Summary: This study numerically investigated the effects of swirl inserts and nanofluids on thermal-hydraulic performance of parabolic trough collectors with non-uniform heating. The combination of straight conical strips alone increased Nusselt number by 47.13%, while adding nanofluids with swirl generators further enhanced it by 57.48%. Different swirl generator designs showed varying levels of improvements, with the larger swirl generator using 6% SiO2 nanofluids proving to be the optimum configuration.
Article
Thermodynamics
Mohamed Iqbal Shajahan, Christopher Stephen, Jee Joe Michael, M. Arulprakasajothi, P. Rathnakumar, M. Parthasarathy
Summary: In this investigation, the application of Multi Walled Carbon Nanotubes (MWCNT)/De-ionized (DI) water nanofluid in compact heat exchangers is studied experimentally and numerically. The results show that nanofluid exhibits better heat transfer performance than the base fluid, and the use of complex geometry inserts further enhances the heat transfer. The numerical results are in good agreement with the experimental results, and the thermal performance factor is found to be greater than unity, indicating improved heat transfer performance with the use of inserts.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2023)
Article
Thermodynamics
Nabeel Abed, Imran Afgan, Andrea Cioncolini, Hector Iacovides, Adel Nasser
Summary: The thermal performance of parabolic trough collectors can be significantly improved by using swirl generator inserts and nanoparticles in the solar receiver, leading to increased energy capture and reduced thermal losses. Testing different strip shapes with and without nanofluids showed that the straight large conical strips with nanofluid had the highest enhancement in Nusselt number, thermal efficiency, and thermal exergy efficiency.
APPLIED THERMAL ENGINEERING
(2022)
Article
Thermodynamics
Krishan Kumar, Rajan Kumar, Rabinder Singh Bharj
Summary: The present study investigates the use of novel corrugated channels for efficient heat dissipation in electronic components. Numerical simulations are performed to analyze entropy generation, heat transfer, and fluid flow. The results show that the corrugated channels improve convective heat transfer compared to simple channels.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2022)
Article
Thermodynamics
S. A. Marzouk, Ahmad Aljabr, Fahad Awjah Almehmadi, Saeed Alqaed, Maisa A. A. Sharaf
Summary: In this study, the performance of a plate heat exchanger is numerically investigated using tungsten carbide (WC) nanoparticles with water. The effect of nanofluid mass concentration on various parameters such as Nusselt number, friction factor, exergy efficiency temperature, velocity, and pressure distribution is analyzed. The results show that increasing the Reynolds number and nanofluid mass concentration can enhance the Nusselt number and reduce the friction factor. The streamlines and contours of the temperature, velocity, and pressure distribution provide credible interpretations for the movements of WC-water nanofluids and an noticed improvement in heat transfer.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2023)
Article
Chemistry, Multidisciplinary
Omer A. A. Alawi, Haslinda Mohamed Kamar, Mayadah W. W. Falah, Omar A. A. Hussein, Ali H. H. Abdelrazek, Waqar Ahmed, Mahmoud Eltaweel, Raad Z. Z. Homod, Nadhir Al-Ansari, Zaher Mundher Yaseen
Summary: Mono, hybrid, and ternary nanofluids were tested in plain and twisted-tape pipes using k-omega shear stress transport turbulence models. The thermal performance and pressure drop of different nanofluids were compared at varying Reynolds numbers. Results showed that the twisted pipe had a higher outlet temperature and better energy utilization than the plain pipe. SiO2/DW exhibited improved heat transfer performance and reduced pressure drop at Re = 9,000. Overall, nanofluids showed superior thermohydraulic performance compared to distilled water, with DW having a higher thermohydraulic efficiency at Re = 15,000.
NANOTECHNOLOGY REVIEWS
(2023)
Review
Thermodynamics
Norhazwani Abd Malek, Siti Ujila Masuri, R. Saidur, Che Nor Aiza Jaafar, Eris Elianddy Supeni, Muhammad Anis Khaliquzzama
Summary: This paper reviews the effect of morphology on heat transfer enhancement in nanofluids containing low-dimensional nanomaterials. The impact of morphology on heat transfer in nanofluids is still unclear. By examining experimental and theoretical studies on the effect of morphology on heat transfer enhancement in nanofluids, a better understanding of heat transfer mechanisms can be achieved.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2023)
Article
Thermodynamics
Sunil Chamoli, Xiaoru Zhuang, Pawan Kumar Pant, Peng Yu
Summary: Inserting tori into conventional smooth tubes can significantly enhance heat transfer efficiency with improved fluid mixing and disruption of boundary layers, leading to the formation of vortex/swirl flow. This design improvement results in higher average Nusselt number and performance evaluation criteria, making tori a favorable device for enhancing tube heat exchanger performance.
APPLIED THERMAL ENGINEERING
(2021)
Article
Thermodynamics
Rahul Bahuguna, K. K. S. Mer, Manoj Kumar, Sunil Chamoli
Summary: This study presents the impact of different geometrical and flow parameters on thermal energy transfer and performance of tube heat exchangers with solid and perforated triple-blade vortex generator inserts. The results show that using the triple-blade vortex generator insert improves the heat transfer performance of the heat exchanger.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2022)
Article
Engineering, Chemical
Qifan Yu, Xianjun Hou, Longxiang Zhang, Hua Jiang, Yuxin Ma, Mohamed Kamal Ahmed Ali
Summary: This study investigates the physicochemical characteristics of ethylene glycol/water-based hydroxyl-functionalized boron nitride and graphite hybrid nanofluids. A novel annealing method is proposed to improve the synergy between hybrid graphite/boron nitride nanoparticles. The dispersion stability, thermal stability, and rheological behavior of various nanofluids are evaluated, and it is found that the G/BN-OH hybrid nanofluids show better dispersion stability, thermal stability, and lower increase in viscosity. The thermal conductivity of G/BN-OH nanofluids is increased by up to 18.05% compared to the base fluid.
ADVANCED POWDER TECHNOLOGY
(2023)
Article
Thermodynamics
Mingzheng Ye, Jianqiang Du, Jin Wang, Lei Chen, Petar Sabev Varbanov, Jiri Jaromir Klemes
Summary: In this paper, a combined structure of fan-shaped cavities and oval pin fins is designed for a rectangular microchannel heat sink. The effects of different structural parameters on the performance are investigated. The results show that the microchannel exhibits improved hydrothermal performance under the optimal parameter combination.
Article
Thermodynamics
Pravin O. Sharma, Surendra D. Barewar, Sandesh S. Chougule
Summary: The study investigated the enhancements in thermal properties, CHF, and HTC of novel Ag/ZnO hybrid nanofluid at various concentrations. It was found that within a certain concentration range, the nanofluid can enhance heat transfer, but exceeding a certain concentration can deteriorate the boiling heat transfer.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2021)
Article
Thermodynamics
L. Syam Sundar, A. H. Misganaw, Manoj K. Singh, Antonio C. M. Sousa, Hafiz Muhammad Ali
Summary: In this study, the thermal efficiency, convective heat transfer, and friction factor analysis of a flat plate solar collector using water and nanodiamond-cobalt oxide hybrid nanofluids were investigated. The hybrid nanofluids showed enhanced thermal properties, resulting in higher heat transfer coefficient and improved thermal efficiency compared to water. Empirical correlations were developed for Nusselt number and friction factor with hybrid nanofluids within a deviation of +/- 3%.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2021)
Article
Materials Science, Multidisciplinary
L. Syam Sundar, Feroz Shaik
Summary: Experimental research was conducted on the heat transfer, entropy generation, and exergy efficiency of ethylene glycol (EG) based nanodiamond (ND) nanofluids flowing in a circular tube. The study showed that the heat transfer coefficients of ND nanofluids were higher than that of the base fluid, and the improvement in entropy generation and exergy efficiency depended on the volume concentration of the nanofluid and Reynolds number.
DIAMOND AND RELATED MATERIALS
(2023)
Article
Engineering, Mechanical
Lingala Syam Sundar, Feroz Shaik, Zafar Said
Summary: Novel MXene materials were dispersed into a mixture of ionic liquid [MMIM][DMP] and water to create ionanofluids. The thermophysical properties of the ionanofluids were experimentally studied at different particle weight loadings and temperatures. Three models were used to analyze the figures-of-merit of the ionanofluids under turbulent flow conditions. Results showed that the thermal conductivity of the ionanofluid at 1.0 wt% increased by 56.62% at 60 degrees C, and the dynamic viscosity increased by 17.66% at 20 degrees C. The obtained thermophysical properties were fitted into regression equations, and the figures-of-merit of the ionanofluids were found to be greater than 1, indicating their effectiveness as heat transfer fluids.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART C-JOURNAL OF MECHANICAL ENGINEERING SCIENCE
(2023)
Article
Green & Sustainable Science & Technology
Kotturu V. V. Chnadra Mouli, L. Syam Sundar, A. M. Alklaibi, Zafar Said, K. V. Sharma, V. Punnaiah, Antonio C. M. Sousa
Summary: This paper experimentally analyzed the thermal efficiency, Nusselt number, exergy efficiency, thermal entropy generation, and frictional entropy generation of natural circulation of water-based multi-walled carbon nanotubes nanofluids flow in a flat plate collector. The results showed that the heat transfer coefficient, Nusselt number, and exergy efficiency increased gradually from 09:00 hr to a maximum value at 13:00 hr and then decreased gradually until the end of the test at 16:30 hr. Regression equations were developed for Nusselt number and friction factor for two time durations. At the peak value of 13:00 hr, the thermal and exergy efficiencies increased significantly compared to water.
SUSTAINABLE ENERGY TECHNOLOGIES AND ASSESSMENTS
(2023)
Article
Engineering, Multidisciplinary
L. Syam Sundar
Summary: The present study experimentally investigated the Nusselt number, exergy efficiency, entropy generation, and thermal performance factor of nanodiamond-Fe3O4/water hybrid nanofluids in a tube with twisted tape inserts. The experiments were conducted under turbulent flow regime with different Reynolds numbers, volume loadings, and twisted tape inserts. The results showed that the addition of nanofluids and twisted tape inserts significantly improved the heat transfer and energy efficiency, while reducing thermal entropy generation. New correlations for Nusselt number and friction factor were proposed.
AIN SHAMS ENGINEERING JOURNAL
(2023)
Article
Thermodynamics
L. Syam Sundar, B. Deepanraj, Hiren K. Mewada
Summary: This study experimentally investigated the heat transfer coefficient, Nusselt number, effectiveness, and number of transfer units of water mixed multi-walled carbon nanotubes nanofluids passing through a tube-in-tube heat exchanger. The parameters were predicted using adaptive neuro fuzzy inference system (ANFIS). The developed structure successfully predicted 96% of variation in all parameters.
CASE STUDIES IN THERMAL ENGINEERING
(2023)
Article
Engineering, Mechanical
Lingala Syam Sundar, Abdulaziz Mohammed Alklaibi, Kotturu V. V. Chandra Mouli, Deepanraj Balakrishnan
Summary: Experimental research was conducted on the heat transfer coefficient and thermal performance of a heat pipe using hybrid nanorefrigerants of R134a/mineral oil (5:1% weight percent) and nanodiamond+Fe3O4. The hybrid nanoparticles were created using an in-situ growth approach and characterized by X-ray diffraction. The results showed that the use of hybrid nanofluids reduced the wall temperatures in the evaporator and condenser sections of the heat pipe and improved the heat transfer coefficients. The thermal performance of the heat pipe was enhanced with increasing particle loadings.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART C-JOURNAL OF MECHANICAL ENGINEERING SCIENCE
(2023)
Article
Nanoscience & Nanotechnology
L. Syam Sundar, Hiren K. Mewada
Summary: The thermophysical properties of ZrO2/ethylene glycol nanofluids at different concentrations were experimentally determined. A two-step method was used to prepare stable nanofluids, and a multi-layer perceptron feed-forward back propagation artificial neural network was developed to predict the target property.
JOURNAL OF NANOFLUIDS
(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)
Review
Chemistry, Physical
Syam Sundar Lingala
Summary: The use of ionic liquid nanofluids as heat transfer fluids has recently gained attention due to the improved thermophysical properties and thermal performance of ionic liquids. The interactions between ionic liquids and nanoparticles contribute to the enhancement of heat transfer rates. This work provides a summary of the thermophysical characteristics of ionic liquids and IL nanofluids, their synthesis methods, and their applications in thermal devices. Suggestions for future research directions are also presented.
Article
Energy & Fuels
S. K. Gugulothu, B. Deepanraj, Ragireddy Venkat Reddy, L. Syam Sundar
Summary: An investigation was conducted on a CRDI engine using a blended fuel (WCO20) to explore the impact of fuel injection strategies on engine characteristics. It was found that the use of WCO20 increased fuel consumption and nitrogen oxide emission while decreasing brake thermal efficiency at a base fuel injection pressure of 40 MPa. The physical properties of the WCO20 fuel blend, such as volatility and viscosity, influenced combustion phenomena and reduced engine performance. Increasing fuel injection pressure led to improved combustion characteristics and higher brake thermal efficiency.
Article
Environmental Sciences
Sathiya Satchi Christopher, Amrit Kumar Thakur, Soumya Kanti Hazra, Swellam Wafa Sharshir, Adarsh Kumar Pandey, Saidur Rahman, Punit Singh, Lingala Syam Sunder, Arun Kumaradas Raj, Ramasamy Dhivagar, Ravishankar Sathyamurthy
Summary: The aim of this research was to develop a model for a solar refrigeration system that utilizes an External Compound Parabolic Collector and a thermal energy storage system for solar water heating in Chennai, India. The system parameters were optimized using TRNSYS software and the optimized system was found to meet 80% of hot water requirements with high annual energy and exergy efficiency. Additionally, the connection of the solar refrigeration system with an optimized solar water heating system demonstrated the potential for efficiently generating cooling energy. The optimization of system parameters and the use of exergy analysis provide valuable insights into the thermal behavior and performance of the system.
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
(2023)
Article
Thermodynamics
L. Syam Sundar, Venkata Ramayya Ancha, Feroz Shaik, Jamal Nayeh
Summary: The advantages of hybrid nanofluids in heat transfer are significant. Thermophysical properties were examined before analyzing heat transfer coefficient in thermal devices. Stable rGO/nanodiamond hybrid nanofluids were manufactured using different ratios of water and ethylene mixture. Experimental analysis was conducted on the thermophysical characteristics at various particle concentrations and temperatures. Results showed an increase in thermal conductivity and viscosity compared to base fluids, but the figures of merit for hybrid nanofluids were less than unity.
JOURNAL OF ENHANCED HEAT TRANSFER
(2023)
Review
Engineering, Multidisciplinary
Lujain Abdullatif Alshuhail, Feroz Shaik, L. Syam Sundar
Summary: There is a tremendous need for energy worldwide, primarily in industrial sectors, and the only option to meet this demand is through the utilization of fossil fuels. However, this usage leads to global warming and environmental pollution. In order to address the finite availability of fossil fuels, it is crucial to rely on renewable energy sources. Solar energy is the most promising renewable energy source and is widely accessible. By using nanofluids and hybrid nanofluids in solar thermal systems, it is possible to increase the thermal efficiency of solar collectors.
ALEXANDRIA ENGINEERING JOURNAL
(2023)
Article
Multidisciplinary Sciences
A. M. Alklaibi, Kotturu V. V. Chandra Mouli, L. Syam Sundar
Summary: This study investigates the performance of Fe3O4-SiO2/water hybrid nanofluids in a plate heat exchanger. Experimental results show that the flow of these hybrid nanofluids remains laminar within the tested flow rates and volumetric concentrations. The support vector machine (SVM) algorithm is used to predict the entropy generation and efficiency of the hybrid nanofluids. The results demonstrate that the Fe3O4-SiO2/water hybrid nanofluids can improve the exergy efficiency and reduce the total entropy generation in the heat exchanger.
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)