Article
Thermodynamics
Rahul Ray, Aurovinda Mohanty, Pandab Patro, Kartik Chandra Tripathy
Summary: This study conducts a performance analysis of branched and interrupted fin heat sinks using numerical simulations to explore the possibility of enhancing heat transfer efficiency. The design that places the secondary fins symmetrically and at the farthest position from the base plate shows the best heat dissipation performance.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2022)
Article
Thermodynamics
Huseyin Zahit Demirag, Mehmet Dogan, Atila Abir Igci
Summary: In this study, experimental and numerical investigations were conducted to examine the heat transfer enhancement and friction factor characteristics of a solar air heater with novel type conic vortex generators on the absorber plate. The experimental results showed that the geometrical parameters played a crucial role in the thermal enhancement factor, with the optimum attack angle, blade angle, and scale ratio achieving the highest thermal enhancement factor. The numerical studies used Fluent software to visualize the fluid velocity, vorticity distributions, temperature, and Nusselt number distributions, as well as the pressure distribution of the vortex generators.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2023)
Article
Thermodynamics
Jiangbo Wang, Ting Fu, Liangcai Zeng, Fue-sang Lien, Xiaolei Deng
Summary: This study investigated the thermal performance of punched rectangular winglet vortex generators in turbulent regime. The results showed that punching holes can reduce heat transfer and friction coefficients, enhance the thermal enhancement factor, and jet flow can improve heat transfer efficiency.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2022)
Article
Thermodynamics
Yang Yang, David S-K Ting, Steve Ray
Summary: The study found that freestream turbulence intensity had the most significant effect on enhancing forced convection, with the local Nu/Nu0 correlating best with turbulent kinetic energy. The maximal averaged Nu/Nu0 over 23 W downstream was observed for Tu = 7% case, within +/- 1 and +/- 4 strip widths cross-stream.
THERMAL SCIENCE AND ENGINEERING PROGRESS
(2021)
Article
Thermodynamics
Yue Yang, JuiKui Mao, Pingting Chen, Feilong Wang, Zecan Tu
Summary: This study compares the heat transfer performance of different VGs configurations through numerical simulations, finding that the downstream common-flow-down configuration of VGs can achieve favorable heat transfer enhancement. By increasing the height of VGs and decreasing the spacing between VGs and the jet, the heat transfer efficiency can be further improved.
APPLIED THERMAL ENGINEERING
(2022)
Review
Energy & Fuels
Xueliang Zhu, Yan Li, Qunzhi Zhu
Summary: In the process of industrial waste heat recovery, phase change heat storage technology is popular due to its high heat storage density and constant temperature absorption/release process. This paper summarizes the development of new fins in the industry and the optimization results of size, shape, and arrangement. The research shows that multi-branch structure, non-uniform fin array, and targeted fin arrangement can enhance heat transfer.
JOURNAL OF ENERGY STORAGE
(2022)
Article
Mechanics
L. Xia, Y. Hua, J. G. Zheng
Summary: The study investigates leading edge flow separation control over a stalled airfoil using a fluidic oscillator, revealing the interaction between oscillating jet and external crossflow leads to the production of spanwise vortices, mitigating flow separation. It is found that a higher mass flow usually leads to a better flow control performance.
Article
Thermodynamics
Alberto Menendez-Pereza, Carlos Fernandez-Aballi Altamirano, Daniel Sacasas Suarez, Cristian Cuevas Barraza, Ruben Borrajo-Pereza
Summary: In this study, a combined geometry of louvered fins and vortex generators is simulated to optimize the thermohydraulic behavior of a compact heat exchanger. The study analyzes the influence of eight parameters of the enhanced surface on its thermohydraulic performance and achieves improvements in convective heat transfer between 6.55% and 19.63% with an increase in pressure losses ranging from 10.95% to 20.67%, depending on the Reynolds number. The optimization is carried out using NSGA-II genetic algorithms and multi-objective optimization technique.
APPLIED THERMAL ENGINEERING
(2022)
Article
Thermodynamics
Xin Cao, Huan-ling Liu, Xiao-dong Shao, Hang-bo Shi
Summary: This paper proposes a novel mini-channel heat sink with tessellated fins and investigates its heat cooling capacity numerically and experimentally. The results show that the new design is more conductive to heat transfer and optimized designs can further improve thermal performance and uniform substrate temperature.
APPLIED THERMAL ENGINEERING
(2022)
Article
Thermodynamics
Anurag Maheswari, Yogesh K. Prajapati
Summary: In the present study, a three-dimensional numerical simulation was conducted to investigate the thermohydraulic performance of a novel design of double-layer microchannel heat sinks. The modified heat sink with an intermediate rectangular fin and different hole shapes significantly enhanced the heat transfer rate by approximately 45-60% compared to the conventional design. However, higher pressure drops were observed due to flow restrictions. Among all the cases considered, heat sinks with circular and triangular holes showed superior thermal performance with a marginal difference of approximately 2-5%. The improved heat transfer rate in the modified heat sink was attributed to better fluid mixing and thinner boundary layers facilitated by the fins with holes. Optimization analysis identified a heat sink with a hole radius of 0.286 mm and 15 holes as the superior configuration, achieving a maximum heat transfer rate approximately 51-64% higher than the conventional design.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2023)
Review
Thermodynamics
Suvanjan Bhattacharyya, Devendra Kumar Vishwakarma, Adithya Srinivasan, Manoj K. Soni, Varun Goel, Mohsen Sharifpur, Mohammad Hossein Ahmadi, Alibek Issakhov, Josua Meyer
Summary: The objective of this article is to study the work carried out in heat transfer augmentation using active and passive techniques. The study reviews research done in various areas such as electrohydrodynamic, magnetic field, corona wind, vortex generators, tape and coil inserts, roughness, and modified duct. It was found that passive methods are more investigated than active methods due to their safe and sound operation along with no additional requirement of power. The results show that duct modification is an effective and efficient way for heat transfer enhancement.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2022)
Article
Thermodynamics
Zhiqi Zhao, Lei Luo, Dandan Qiu, Zhongqi Wang, Bengt Sunden
Summary: A numerical study was conducted to investigate convective heat transfer enhancement and friction loss behaviors in turbulent flow using differently shaped ribs and deltawinglet vortex generators in a solar air heater. The results showed that combining deltawinglet vortex generators with 60 degrees V-shaped continuous ribs resulted in the best heat transfer performance, with a 39.4% enhancement compared to using only the vortex generators.
Article
Thermodynamics
Takumi Ohta, Akihiko Mitsuishi, Takaaki Shimura, Kaoru Iwamoto, Akira Murata
Summary: This study investigated the influence of mainstream angle on laminar boundary layer flow with arrays of tetrahedral vortex generators (VGs) through direct numerical simulations. It was found that the highest heat transfer effect was observed when the mainstream angle was 60 degrees. The analysis revealed that advection induced by vortex pairs was the dominant factor at zero yaw angle, while heat transfer was enhanced by a turbulent component as the mainstream angle increased. Additionally, installing multiple VGs in the longitudinal direction led to a higher heat transfer enhancement effect, which was remarkable when VGs were aligned in the mainstream direction.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Thermodynamics
Siwei Tang, Gongnan Xie, Guohua Zhang, Bengt Sunden
Summary: This article investigates the effects of traditional delta winglet pair vortex generators (DWPVG) with slits on pressure drops and heat transfer performances in a rectangular channel. Through three-dimensional calculations and analysis of thermo-fluid processes, it is found that induced vortices are located closer to the bottom surface, improving the local Nusselt number behind DWPVG when the fluid flows through slits. Furthermore, DWPVG with slits decreases the pressure drop and improves the local thermal efficiency in the channel with a high blocking ratio. The overall thermal performance of the slit DWPVG channel with a high blocking ratio increases with the increase in Reynolds number, and the highest heat transfer enhancement is achieved by opening slits on five DWPVGs in the rectangular channel.
NUMERICAL HEAT TRANSFER PART A-APPLICATIONS
(2023)
Article
Thermodynamics
Jiangbo Wang, Ting Fu, Liangcai Zeng, Fue-sang Lien, Guang Chen
Summary: The punched delta winglet (PDW) was found to enhance local heat transfer efficiency while slightly affecting overall heat transfer coefficient and reducing pressure loss in the channel. Among holes with the same area, the larger width and lower height of the hole resulted in the highest thermal enhanced factor (TEF).
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2022)
Article
Thermodynamics
Ruben Borrajo Perez, Alberto Menendez Perez, Daniel Sacasas Suarez
Summary: This study numerically investigates the impact of a pair of perforated vortex generators (VGs) punched on the surface of a rectangular channel on its thermohydraulic performance. The results show that VGs enhance heat transfer efficiency and produce lower pressure loss, especially for Reynolds numbers higher than 120, indicating significant advantages.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Thermodynamics
Alberto Menendez-Pereza, Carlos Fernandez-Aballi Altamirano, Daniel Sacasas Suarez, Cristian Cuevas Barraza, Ruben Borrajo-Pereza
Summary: In this study, a combined geometry of louvered fins and vortex generators is simulated to optimize the thermohydraulic behavior of a compact heat exchanger. The study analyzes the influence of eight parameters of the enhanced surface on its thermohydraulic performance and achieves improvements in convective heat transfer between 6.55% and 19.63% with an increase in pressure losses ranging from 10.95% to 20.67%, depending on the Reynolds number. The optimization is carried out using NSGA-II genetic algorithms and multi-objective optimization technique.
APPLIED THERMAL ENGINEERING
(2022)
Article
Thermodynamics
Daniel Sacasas, Javier Vega, Cristian Cuevas, Alberto Menendez, Ruben Borrajo
Summary: This study introduces an improved methodology to accurately evaluate the performance of a conventional R404A system and a Booster R744 system. The improved modeling and control system enhance the accuracy and performance of the compressors, allowing for a comparison of both systems at different ambient temperatures.
INTERNATIONAL JOURNAL OF REFRIGERATION
(2023)
Article
Thermodynamics
Ruben Borrajo-Perez, Alberto Menendez-Perez, Daniel Sacasas-Suarez
Summary: Heat transfer enhancement is a constant objective in heat exchanger design, and vortex generators are a passive technique that can improve heat exchanger performance by disrupting boundary layers and creating secondary flows. In this study, the influence of punched holes on rectangular channels with built-in vortex generators was numerically analyzed. The arrangement with punched holes in front of the vortex generators achieved the best overall performance, doubling the heat transfer enhancement while also increasing pressure drop.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2023)
Article
Social Sciences, Interdisciplinary
Alberto Menendez Perez, Alejandro Rosete, Ernesto Lorenzo Bonet, Daniel Sacasas Suarez, Ruben Borrajo Perez
Summary: This paper presents a numerical study of compact heat exchangers with circular tubes and louver fins that use vortex generators. The influence of the inclination angle of the vortex generators on the heat transfer and the pressure drop is determined. Optimized solutions are found to enhance heat transfer by 7% with only a 5% increase in pressure loss.
REVISTA UNIVERSIDAD Y SOCIEDAD
(2022)
Article
Thermodynamics
Alberto Menendez Perez, Carlos Fernandez-Aballi Altamirano, Ruben Borrajo Perez
Summary: This paper investigates the performance of vortex generators in compact louvered fins and tubes heat exchangers. The study reveals the relationship between the performance of vortex generators and design parameters, as well as the impact of different parameters on heat transfer and pressure losses.
THERMAL SCIENCE AND ENGINEERING PROGRESS
(2022)
Review
Thermodynamics
Shuling Guo, Ankuo Zhang
Summary: Low-temperature biopreservation is commonly used for medication storage to prolong their shelf life. However, cryo-injury can occur during cryopreservation, making it crucial to find a way to achieve long-term biopreservation without causing harm. The optimal storage temperature for different biomaterials should be investigated to improve storage efficiency. This review discusses the mechanisms of cryo-injury and biopreservation, as well as the reasons for storing biological tissues at various temperature zones. It provides valuable insights for the development of biostorage technology.
INTERNATIONAL JOURNAL OF REFRIGERATION
(2024)
Article
Thermodynamics
M. Mohsin Tanveer, Craig R. Bradshaw, Joe Orosz, Greg Kemp
Summary: This study investigates the optimal geometric parameters for a spool compressor using simulation models, and the results indicate that a eccentricity ratio of 0.75 and L/D ratios between 1-1.5 can maximize the volumetric and isentropic efficiencies.
INTERNATIONAL JOURNAL OF REFRIGERATION
(2024)
Article
Thermodynamics
Kongkuai Ying, Zhenhua Jiang, Wenting Wu, Jinjian Chu, Shaoshuai Liu, Yinong Wu
Summary: The Stirling/pulse tube cryocooler (SPC) is a highly efficient and long-lasting cryocooler for space applications. It has the ability to adjust the inter-stage refrigeration capacity dynamically by controlling the Stirling displacer in the first stage. This paper proposes an SPC with a second-stage active phase shifter (APS) that can control the phase difference at the second-stage hot end in real time. The experimental results show that the SPC with the APS can provide refrigeration capacity at different temperatures, with a minimum temperature of 13.5K.
INTERNATIONAL JOURNAL OF REFRIGERATION
(2024)
Article
Thermodynamics
Ligeng Li, Hua Tian, Kai Liu, Yibo Wu, Xuan Wang, Xingyu Liang, Gequn Shu
Summary: This study focuses on improving the performance of carbon dioxide refrigeration systems by introducing a multi-ejector design with three controllable ejectors. Experimental analysis shows that the system's performance can be significantly improved by adopting an optimum pressure control strategy under different operating conditions.
INTERNATIONAL JOURNAL OF REFRIGERATION
(2024)
Article
Thermodynamics
Joseph Al Khoury, Rabih Al Haddad, Ghiwa Shakrina, Christelle Bou Malham, Haytham Sayah, Chakib Bouallou, Maroun Nemer
Summary: This study investigates two implementation methods for calculating refrigerant thermodynamic properties and compares their performance. The results show that the implicit fitting method significantly speeds up simulation time and offers greater flexibility for modeling complex energy systems.
INTERNATIONAL JOURNAL OF REFRIGERATION
(2024)
Article
Thermodynamics
Mariella Mateo-Villanueva, Rodolfo Echarri
Summary: This article details three models of different complexity levels for predicting the cold production of a solar cooling device and compares their advantages and disadvantages. The results show that the transient model underestimates the cold generation, while the equilibrium model and universal model overestimate it. The transient model is a useful tool for analyzing the impact of different variables in a solar adsorption refrigeration system, while the simpler models can be used for preliminary design and feasibility studies.
INTERNATIONAL JOURNAL OF REFRIGERATION
(2024)
Article
Thermodynamics
Amin M. Elsafi, Majid Bahrami
Summary: The novel spherical micro-absorbers offer high sorption capacity and surface-to-volume ratios, solving issues such as solution carryover and corrosion associated with conventional absorbers.
INTERNATIONAL JOURNAL OF REFRIGERATION
(2024)
