Article
Thermodynamics
Balaga Ravikiran, Koona Ramji, Tunuguntla Subrahmanyam
Summary: This study investigates the thermal performance of a combination of twisted tapes, perforated twisted tapes, and wire coils in a circular tube with water as the working fluid under turbulent flow conditions. The results show that these combined effects can significantly enhance the convective heat transfer coefficient and friction factor by mechanisms such as reversed flow, swirling flow, and impinging flow, ultimately improving the thermal performance of the circular tube.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2021)
Article
Thermodynamics
A. Garcia, R. Herrero-Martin, J. Perez-Garcia, J. P. Solano
Summary: This paper presents a new methodology based on a non-dimensional geometry-based parameter to predict the friction coefficient evolution and transitional flow region extension of wire-coil inserts. The experimental validation shows that this methodology is a valuable tool for selecting the most appropriate wire-coil geometry. The case study demonstrates that wire-coil geometry with early transition effect can improve the thermal performance.
APPLIED THERMAL ENGINEERING
(2023)
Article
Thermodynamics
A. Martin Subirana, J. P. Solano, R. Herrero-Martin, A. Garcia, J. Perez-Garcia
Summary: This study investigates the flow and heat transfer in a helical coil under laminar and transitional flow regimes, considering mixed convection conditions. The continuous separation and reattachment of the boundary layer caused by the wire coil, as well as the swirl induced by the helical shape of the insert, are identified as mechanisms for enhancing heat transfer. Simulations in the Reynolds number range 200 < Re < 1500 show the sensitivity of heat transfer to mixed convection, as the flow dynamics is affected by buoyancy forces induced by tube wall heating. The interaction between the secondary swirl flow and buoyancy motion is examined to determine the range where heat transfer may be worsened by the presence of the helical coil. The study considers a helical coil with geometrical characteristics e/D = 0.071 and p/D = 1.5, using water as the working fluid. Experimental validation of friction factor and Nusselt number is also provided.
THERMAL SCIENCE AND ENGINEERING PROGRESS
(2023)
Article
Thermodynamics
Teerapat Chompookham, Witoon Chingtuaythong, Suriya Chokphoemphun
Summary: The experimental study involved the insertion of a novel wire coil turbulator, referred to as serrated wire coil (SWC), into a tube heat exchanger to enhance heat transfer performance. Results showed significant improvement in heat transfer efficiency with SWC inserts, supported by developed empirical correlations with acceptable error margins.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2022)
Article
Green & Sustainable Science & Technology
Ravi Kumar, Ankit Kumar Pathak, Manoj Kumar, Anil Kumar Patil
Summary: The study investigates the performance of a sensible heat storage system consisting of concrete with wire coil inserts, which is able to store thermal energy from heated air. The system achieves higher energy efficiency and capacity factor when using wire coil inserts with a pitch to diameter ratio of 0.5.
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
Zhenfei Feng, Qingyuan Zhang, Zhenzhou Li, Yongrui Bian, Zhenjun Hu, Jinxin Zhang, Fangwen Guo, Feng Du
Summary: Energy conservation and emission reduction are important international policies. For micro/mini-channel heat exchangers, improving thermal performance while consuming less energy is crucial. Swirling flow, induced by wire coil inserts, has been effective in enhancing heat transfer in traditional heat exchangers, but its effects on hydrothermal and energy-saving performances in square micro/mini-channels remain uncertain.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2023)
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
Thermodynamics
Iyyamperumal Seerangan, Ting-Hsuan Huang, Yao-Hsien Liu
Summary: Enhanced heat transfer and friction factor were observed in a rectangular minichannel heat sink with coiled wire inserts, leading to the proposal of a partially-filled design to reduce pressure drop. The Nusselt number and friction factor increased with wire diameter but decreased with an increase in pitch-to-diameter ratio, resulting in the highest thermal performance with partially-filled coiled wires in the minichannel.
HEAT AND MASS TRANSFER
(2021)
Article
Thermodynamics
Fayez Aldawi
Summary: A numerical study is conducted to evaluate the thermal and frictional characteristics of flat coil tube with spring inserts. The results show that the flat coil tube with spring inserts is more compact and has higher Nu number compared to the plain coil tube.
CASE STUDIES IN THERMAL ENGINEERING
(2022)
Article
Energy & Fuels
Ravi Kumar, Manoj Kumar, Anil Kumar Patil
Summary: Transient energy storage in a sensible energy storage system (SESS) is dependent on the rate of energy stored, which in turn strongly relates to the spatial temperature distribution regulating energy distribution in the storage medium. This study examines energy and capacity factor characteristics in a wire coil fitted multi-tubular SESS, showing that optimizing the design of the coil inserts can significantly improve the system's capacity factor.
INTERNATIONAL JOURNAL OF ENERGY RESEARCH
(2022)
Article
Thermodynamics
Nitesh K. Panday, Shailendra N. Singh
Summary: The experimental investigation in this study focuses on the impact of wire inserts in the channel flow path on the thermal and hydraulic performance of single-pass plate heat exchangers (PHEs). A modified Wilson plot method is proposed for calculating heat transfer coefficient for different flow rates of working fluids. The results show that the chevron angle of the plates has a significant influence on heat transfer enhancement at different pressure drops.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2022)
Article
Thermodynamics
Yi Wang, Jorge L. Alvarado, Wilson Terrell
Summary: In this study, the flow and heat transfer characteristics of microencapsulated phase change material (MPCM) slurry were experimentally investigated using a newly designed helical coil heat transfer device. The structural modifications enhanced the heat transfer performance of MPCM slurry and the phase change process considerably improved the heat transfer rate.
EXPERIMENTAL HEAT TRANSFER
(2023)
Article
Environmental Sciences
Amirhossein Zabihi Sheshpoli, Omid Jahanian, Kamyar Nikzadfar
Summary: This study investigates the strict reasons to rely on renewable energy sources like solar energy rather than fossil fuels through a numerical/experimental investigation on a hybrid photovoltaic/thermal system. Wire coils were used as a passive method to improve heat transfer, and the appropriate number of wire coils was determined through numerical simulation. The results show that placing three wire coils inside the cooling tube can significantly increase the average electrical and thermal efficiency.
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
(2023)
Article
Thermodynamics
Mohamed T. T. Abdelghany, Samir M. M. Elshamy, M. A. Sharafeldin, O. E. Abdellatif
Summary: An active technique using a solenoid valve as a pulse generator was employed to enhance the heat transfer rate in a conical coiled tube (CCT) in this study. Experimental investigation was conducted to study the effect of pulsation on heat transfer and pressure drop in the CCT. The results showed that pulsating flow at a frequency of 4 Hz yields the highest heat transfer enhancement among the tested frequencies, and reducing the pulse frequency and coil torsion can improve heat transfer characteristics.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2023)
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)