Article
Thermodynamics
Santinath Bairagi, Ranendra Roy, Bijan Kumar Mandal
Summary: This study conducts a numerical investigation on the heat transfer properties of water-based Al2O3 nanofluids flowing through circular tubes, both with and without twisted tape inserts. The results show that twisted tape significantly enhances the heat transfer rate, while the nanofluid alone only provides a modest improvement. The friction factor increases with the nanoparticle volume fraction, but the effect on heat transfer rate is more pronounced. The best thermohydraulic performance is achieved with a 5% volume fraction of nanoparticles and twisted tape inserts.
JOURNAL OF THERMAL SCIENCE AND ENGINEERING APPLICATIONS
(2023)
Article
Thermodynamics
Keyvan Ahmadi, Saber Khanmohammadi, Shoaib Khanmohammadi, Mehdi Bahiraei, Quang-Vu Bach
Summary: In this study, a numerical simulation is conducted to improve the thermal performance of a circular pipe using elliptical-cut twisted tape inserts and nanofluid. The results show that the use of elliptical-cut twisted tape and nanofluid can significantly enhance heat transfer and thermal efficiency factor.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2022)
Article
Thermodynamics
H. Harish, K. Manjunath
Summary: This research compares the flow and heat transfer properties of water with circular protruded twisted-tape inserts to those with traditional twisted tapes. The study found that circular protruded twisted-tape inserts provide higher thermal enhancement and lower friction factor.
CASE STUDIES IN THERMAL ENGINEERING
(2022)
Article
Chemistry, Multidisciplinary
Yongfeng Ju, Tiezhu Zhu, Ramin Mashayekhi, Hayder Mohammed, Afrasyab Khan, Pouyan Talebizadehsardari, Wahiba Yaici
Summary: Increasing the number of semi-twisted tapes in a heat exchanger pipe leads to enhancement in heat transfer and friction factor, which is significant for heat exchange using nanofluids.
Article
Thermodynamics
Chulin Yu, Yulin Cui, Haiqing Zhang, Bingjun Gao, Min Zeng, Lei Han
Summary: In this paper, the overall thermal-hydraulic performance of new enhanced tubes with different twisted tapes was numerically studied. The results showed that the Nusselt number and friction factor of twisted tubes with twisted tapes were significantly increased, and the twisted tube with center cleared twisted tape had the highest performance evaluation criterion.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2022)
Article
Mechanics
Edris Bagheri, Bing-Chen Wang
Summary: The radius ratio has a significant impact on the Nusselt numbers and skin friction coefficients of the inner and outer cylinder walls, as well as on the development and interaction of thermal boundary layers. Turbulent heat transfer is more intense on the outer cylinder side, and as the radius ratio decreases, the differences in turbulence statistics between the inner and outer cylinder sides become more pronounced. Additionally, the most energetic turbulent thermal structures have larger characteristic length scales on the inner cylinder side.
Article
Chemistry, Multidisciplinary
Ahmed Ramadhan Al-Obaidi
Summary: Numerical simulation was used to analyze the behavior of a flow field, pressure drop and hydraulic thermal performance. The results showed that the insertion of twisted tape in the pipe increased the pressure difference and flow resistance, resulting in a higher temperature difference. The twisted tape created vortex motion and different radial velocities, altering the behavior of the fluid. The geometric parameters of the twisted tape had an influence on the results, but the temperature difference increased less compared to a smooth pipe.
KOREAN JOURNAL OF CHEMICAL ENGINEERING
(2023)
Article
Engineering, Mechanical
S. H. Labib, M. R. A. Himel, J. Ali, A. R. Mim, M. J. Hossain, A. K. Ghosh, A. Goswami
Summary: Experimental and numerical analyses were conducted to investigate the influence of twisted tape inserts on heat transfer and flow behavior in double tube heat exchangers. The results showed that inserting twisted tapes with different twist ratios can enhance heat transfer performance, with the lowest twist ratio achieving the best thermal performance factor. Good agreement between numerical and experimental results indicates the reliability of the numerical model in predicting flow and heat transfer behavior in double tube heat exchangers.
JOURNAL OF MECHANICAL ENGINEERING AND SCIENCES
(2021)
Article
Thermodynamics
Ramin Mashayekhi, Hossein Arasteh, Pouyan Talebizadehsardari, Apurv Kumar, Morteza Hangi, Alireza Rahbari
Summary: By simulating the effects of different design parameters, it is found that inserting twisted tape inside a plain tube can significantly enhance heat transfer performance, with rotating twisted tape showing more prominent improvement. With the increase in Reynolds number, the enhancement in average Nusselt number increases in stationary configurations and decreases in rotating configurations.
HEAT TRANSFER ENGINEERING
(2022)
Article
Thermodynamics
Waleed A. Abdelmaksoud, Alaa E. Mahfouz, Essam E. Khalil
Summary: The study aims to investigate the thermal performance of a heat exchanger tube fitted with vortex generator inserts using numerical methods. Three configurations of vortex generators are proposed to achieve the highest thermal performance, with the triple-curved vortex generator showing the best results at low Reynolds numbers. The thermal performance improves as the pitch ratio decreases, with the triple-curved vortex generator providing a 24% enhancement compared to a twisted tape.
HEAT TRANSFER ENGINEERING
(2021)
Article
Environmental Sciences
Elumalai Vengadesan, Ramalingam Senthil
Summary: This study investigates the effects of single-slit twisted tape, double-slit twisted tape, and double-slit straight tape passive-insert devices on the heat transfer of a flat plate solar collector. The results show that the double-slit inserts enhance the convective heat transfer coefficient and improve energy and exergy efficiency compared to conventional collectors without flow inserts.
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
(2022)
Article
Thermodynamics
Toygun Dagdevir, Veysel Ozceyhan
Summary: The effects of different twisted tapes on heat transfer and flow characteristics in a heat exchanger tube were experimentally investigated to enhance performance. Results showed that twisted tape inserts improved heat transfer performance, with the novel dimpled twisted tape insert providing the best performance. Addition of ethylene glycol did not significantly increase the friction factor, and higher ethylene glycol content led to decreased thermo-hydraulic performance.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2021)
Article
Energy & Fuels
Boonsong Samutpraphut, Smith Eiamsa-ard, Varesa Chuwattanakul, Chinaruk Thianpong, Naoki Maruyama, Masafumi Hirota
Summary: This article explores the use of sawtooth twisted tapes to enhance heat transfer rate by generating swirling flow and interrupted flowing disturbance. The effects of sawtooth angles on heat transfer rate, friction factor, and aerothermal performance index are analyzed. The results show that the sawtooth twisted tape improves heat transfer rate and introduces varying levels of pressure loss based on the sawtooth angles. The recommended sawtooth twisted tape outperforms the typical twisted tape and plain tube in terms of Nusselt number.
Article
Thermodynamics
Abdussamet Subasi, Kasim Erdem
Summary: In this study, a hybrid approach combining MOO and MCDM techniques was used to enhance heat transfer in pipes by evaluating the performance of different nanofluids and inserts. The optimal design parameters were determined using MOO study and TOPSIS method, assisting decision-makers in selecting the best solution among Pareto optimal solutions. The combination of twisted tape and CNT-Fe3O4 nanofluid exhibited the best thermal-hydraulic performance for equal weights of criteria.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Thermodynamics
Anil Kumar, Rajesh Maithani, Masood Ashraf Ali, Naveen Kumar Gupta, Sachin Sharma, Tabish Alam, Hasan Sh Majdi, T. M. Yunus Khan, Anil Singh Yadav, Sayed M. Eldin
Summary: This article introduces the use of twisted tape inserts on the absorber plate of a flat plate solar heat collector to increase its efficiency. The thermal and hydraulic performance of the absorber plate is analyzed by varying the twist pitch and twist height. Computational fluid dynamics is used to perform the analysis, and a maximum thermal-hydraulic performance value of 2.41 is observed for specific twisted tape parameters.
CASE STUDIES IN THERMAL ENGINEERING
(2023)
Article
Thermodynamics
Hayder Mohammad Jaffal, Ihsan Ali Ghani, Ahmed Ramadhan Al-Obaidi
Summary: The 3D numerical analysis evaluated a new configuration of corrugated tube with interruptions, finding that the Nusselt number was 39% higher than the conventional smooth tube. The interruptions in corrugations significantly reduced pressure drop while increasing the flow area.
CASE STUDIES IN THERMAL ENGINEERING
(2021)
Article
Engineering, Multidisciplinary
Ahmed Ramadhan Al-Obaidi, Ali Qubian
Summary: In this study, numerical calculations using CFD code were conducted to investigate the flow field and pressure fluctuations in a centrifugal pump under different outlet impeller diameters. The results provide valuable insights for optimizing pump performance and characteristics.
INTERNATIONAL JOURNAL OF NONLINEAR SCIENCES AND NUMERICAL SIMULATION
(2022)
Article
Thermodynamics
Ahmed Ramadhan Al-Obaidi
Summary: In this study, through numerical simulations, the flow behavior, pressure drop, and heat transfer enhancement in a corrugated pipe were analyzed. It was found that as the Reynolds number increased, the Nusselt number also increased, and with increased corrugated geometry, the pressure drop, turbulent kinetic energy, and vorticity also increased.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2022)
Article
Thermodynamics
Ahmed Ramadhan Al-Obaidi, Jassim Alhamid, Hussam Ali Khalaf
Summary: The effects of mixing secondary, spiral, and swirl flows on heat transfer and pressure drop in internal corrugated tubes with varying Reynolds numbers were examined. The results showed that heat transfer enhancement can be attributed to the convective heat transfer transformation and the redevelopment of the boundary layer by pulsation. Different corrugated geometrical configurations were also investigated, and it was found that higher configurations led to increased heat transfer. Using different corrugated geometric configurations resulted in improved performance compared to smooth pipes.
CASE STUDIES IN THERMAL ENGINEERING
(2022)
Article
Thermodynamics
Jassim Alhamid, Ahmed Ramadhan Al-Obaidi, H. Towsyfyan
Summary: This study successfully enhances the thermal performance of heat exchangers through the use of enhanced pipes, with the 4 mm dimple diameter model showing the highest heat transfer enhancement among other designs. The research demonstrates that perforated geometrical parameters can lead to high fluid mixing and flow perturbation between the pipe core region and the walls, improving thermal efficiency.
Article
Thermodynamics
Ahmed Ramadhan Al-Obaidi
Summary: The current investigation numerically evaluates the influence of various twisted tape configurations on heat transfer and thermal performance, with emphasis on the design optimization through Taguchi analysis and computational fluid dynamics numerical methodology. The best design of twisted tape is identified to enhance heat transfer and overall performance.
Article
Thermodynamics
Ahmed Ramadhan Al-Obaidi, Jassim Alhamid
Summary: This investigation used numerical simulation techniques to study the thermo-hydraulic flow behavior, heat transfer enhancement, and overall thermal performance of fluid passing within a corrugated pipe. The results showed that an increase in corrugated configurations led to a greater pressure drop and higher Nusselt number values. The study also developed correlation equations for the friction factor, Nusselt number, and thermal performance factor.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2022)
Article
Thermodynamics
Ahmed Ramadhan Al-Obaidi
Summary: In this research, the effect of different geometrical parameters on the flow field and thermal heat transfer performance of a heat exchanger design were investigated. Computational simulations were used to analyze the hydraulic thermal fluid coupling, and the results were validated with experimental data. The study found that using corrugated tubes improved heat transfer compared to smooth pipes, and optimization of design parameters enhanced heat transfer rate. The findings suggest that corrugated pipes can be an effective passive device to improve heat transfer in pipes.
Article
Thermodynamics
Ahmed Ramadhan Al-Obaidi
Summary: Improving heat transfer is a significant field in different energy conservation types that is directly connected to systems of economic efficiency. Numerical investigations were conducted to analyze the impact of various twisted tape parameters on thermal performance, with the use of CFD methodology showing better results.
Article
Engineering, Mechanical
Ahmed Ramadhan Al-Obaidi, Jassim Alhamid
Summary: This study investigates the mixed-flow dynamics of axial pumps under five operational conditions, from optimal to the QBEP plus value. In addition, the effects of blade angle on pump performance are examined by considering three angles. The results show that the flow stability of the axial pump deteriorated as the flow decreased, and increasing the blade angle influenced the machine's flow and pressure field characteristics. This study contributes to a more thorough understanding of pump flow dynamics, benefiting researchers and engineers.
IRANIAN JOURNAL OF SCIENCE AND TECHNOLOGY-TRANSACTIONS OF MECHANICAL ENGINEERING
(2023)
Article
Energy & Fuels
Ahmed Ramadhan Al-Obaidi
Summary: The existing numerical research focuses on studying the effects of dimples on the inner wall of heat exchanger pipes. Computational calculations and optimization techniques are used to analyze the influence of various geometrical parameters and improve heat transfer performance. The results show that the use of dimples on the inner pipe surface can enhance heat performance and increase the area of heat transfer. Hydrodynamic analysis, optimization, and improvement of heat transfer performance are necessary for different design applications.
ENERGY SOURCES PART A-RECOVERY UTILIZATION AND ENVIRONMENTAL EFFECTS
(2023)
Article
Engineering, Mechanical
A. R. Al-Obaidi
Summary: In this research, the impact of guide vanes on flow analysis in axial pumps is investigated using unsteady numerical turbulence simulations. The results show that the addition of guide vanes significantly affects the flow field and performance of the pump, leading to improved pump performance and increased pressure, kinetic energy, shear stress, and velocity. This study provides important information and guidance for enhancing and improving the design and operation of axial flow pumps.
EXPERIMENTAL TECHNIQUES
(2023)
Article
Chemistry, Multidisciplinary
Ahmed Ramadhan Al-Obaidi
Summary: Numerical simulation was used to analyze the behavior of a flow field, pressure drop and hydraulic thermal performance. The results showed that the insertion of twisted tape in the pipe increased the pressure difference and flow resistance, resulting in a higher temperature difference. The twisted tape created vortex motion and different radial velocities, altering the behavior of the fluid. The geometric parameters of the twisted tape had an influence on the results, but the temperature difference increased less compared to a smooth pipe.
KOREAN JOURNAL OF CHEMICAL ENGINEERING
(2023)
Article
Acoustics
Ahmed Ramadhan Al-Obaidi
Summary: Condition monitoring in centrifugal pumps is important and the acoustic method is used to detect cavitations. The acoustic technique provides detailed information on cavitation detection under different conditions. Time domain analysis and fast Fourier method are used to analyze signals, which have shown to be effective in predicting future events. The experimental investigation aims to establish a correlation between noise characteristics and cavitation detection in a pump, as well as find a good method for estimating cavitation levels in a pump.
ARCHIVES OF ACOUSTICS
(2023)
Article
Thermodynamics
Ahmed Ramadhan Al-Obaidi
Summary: This study investigated the heat-transfer enhancement and pressure drop in turbulent flow of a three-dimensional circular tube with different dimple arrays using computational fluid dynamics numerical methods. The results showed that using 2 mm dimple tubes in low flow range can achieve higher heat transfer rates compared to smooth pipes, which is an important improvement for energy conversion applications.