Article
Thermodynamics
Jing He, Jianghong Wu, Hangye Zhang, Yaokang Zhang, Biwang Lu
Summary: This study investigates a three-dimensional solid-state magnetic refrigerator based on micro-unit regeneration cycle and Peltier elements, and verifies the reliability of the model with experimental data. The comparison of heat transfer processes and performance characteristics under different configurations reveals that coupling with Peltier elements increases temperature span and frequency, while the parallel-plate heat transfer structure of the magnetocaloric material lattice enhances system performance.
APPLIED THERMAL ENGINEERING
(2021)
Article
Thermodynamics
Peng Hai, Jun Shen, Zhenxing Li, Ke Li, Hongmei Huang, Wenshuai Zheng, Wei Dai, Xinqiang Gao, Zhaojun Mo
Summary: In magnetic refrigerators, the operation profiles, including flow profile and magnetic field profile, significantly affect system performance. This study focuses on the influence of magnetic field profile in a rotary magnetic refrigerator. Experimental investigation reveals that the intermittent magnetic field profile outperforms the continuous profile in terms of temperature span and cooling power at frequencies of 0.25, 0.40, and 0.55 Hz. Moreover, a higher temperature span of 22.7 K is achieved with the intermittent profile at a frequency of 0.55 Hz and a utilization factor of 0.52 compared to the continuous profile. Furthermore, a comprehensive study of three blow fractions (0.35, 0.5, and 0.65) for a better intermittent profile demonstrates that the increase in blow fraction leads to a slight improvement in temperature span and cooling power.
APPLIED THERMAL ENGINEERING
(2023)
Article
Thermodynamics
A. T. D. Nakashima, G. F. Peixer, J. A. Lozano, J. R. Barbosa Jr
Summary: This study presents a dynamic lumped parameter model to predict the cabinet temperature, energy consumption and efficiency parameters of a small capacity magnetic refrigerator. The model's primary inputs are geometric features, power source frequencies and speeds, and magnetic material compositions and properties. Special emphasis is placed on the lumped AMR model, which accurately predicts performance based on experimental validation.
APPLIED THERMAL ENGINEERING
(2022)
Article
Thermodynamics
Zhuo Chen, Mingjian Liao, Xiaoming Hu, Yan Ma, Shangwei Jiang, Xin Chen, Fuxiang Zou, Xi'an Fan, Zhu He
Summary: This paper presents a thermoelectric refrigerator used under natural convection heat transfer conditions. Numerical simulations and experimental analyses are performed to obtain the temperature and velocity field distributions in the refrigerator chamber. The influences of the operating current and the height of fins on the temperature are analyzed. The novel design reduces the number of thermoelectric legs in a single TEC to five pairs to reduce the heat generated on the hot side during operation. The performance of TEC is improved by increasing the average heat dissipation area. The results show stable air temperature in the chamber at 12.2°C under specific conditions and an increase in temperature difference with fin's height, while the coefficient of performance (COP) remains relatively unchanged.
APPLIED THERMAL ENGINEERING
(2023)
Article
Materials Science, Multidisciplinary
Bibek Bhandari, Andrew N. Jordan
Summary: The study reveals that multilevel quantum systems, such as qutrits, provide better cooling effect compared to qubits in the refrigeration process. Using Keldysh nonequilibrium Green's function formalism, the research goes beyond first order sequential tunneling processes to analyze the impact of higher order processes on refrigeration, finding a reduced cooling effect compared to traditional master equation calculations.
Article
Engineering, Multidisciplinary
Zhongwei Zhang, Munthir Mohammed Radhy Al Kubaisy, Sabah Auda Abdul Ameer, Ali Jawad Alrubaie, Amgen Mohammed, Samar Emad Izzat, Ayat Hussein Adhab, Emad Salaam Abood, Navid Nasajpour-Esfahani, D. T. Semirumi, Roozbeh Sabetvand
Summary: Recently, oscillating heat pipes filled with nanofluid have attracted attention due to their improved thermal conductivity and heat/mass transfer characteristics. This study focuses on adding Fe3O4 nanoparticles to the nanofluid to enhance the efficiency of the designed structures. Numerical findings show that the thermal behavior of the Fe3O4-H2O nanofluid improves as the nanoparticle radius increases. Additionally, the presence of an external magnetic field enhances the thermal behavior of the nanofluid in the heat pipe.
ALEXANDRIA ENGINEERING JOURNAL
(2023)
Article
Thermodynamics
Shijie Xu, Min Wang, Lili Han, Shoujie Zhang, Jianlin Yu, Suxin Qian
Summary: This study proposes a novel co-simulation method, ROM, to approximate the temperature transients in refrigeration systems. By extracting special parameters from CFD results, the ROM can accurately simulate the dynamic temperature changes.
APPLIED THERMAL ENGINEERING
(2023)
Article
Thermodynamics
Jiatao Guo, Yongchang Chen, Jincao Hu, Ziyan Xu, Chongfang Ma
Summary: A numerical study was conducted to investigate the effects of transverse uniform and gradient magnetic field on the turbulent flow and heat transfer characteristics of low melting point molten salt in a stainless steel pipe based on a modified magnetohydrodynamic turbulence model. The numerical results showed that the flow displayed anisotropic distributions under the magnetic field, with decreased velocity in the mainstream region and turbulent intensity, while the flow velocity increased in the boundary layer near the Hartmann and Roberts wall. The flow and heat transfer displayed more variations under the gradient magnetic field compared to the uniform magnetic field.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2023)
Article
Thermodynamics
Jing He, Chunwan Ya, Xing Tang, Li Ma, Jianghong Wu, Biwang Lu
Summary: This research describes and numerically simulates a novel reciprocating solid state magnetic refrigeration cycle at room temperature. The regenerative process is spontaneously completed between high-and low-temperature magnetocaloric material (MCM) lattices due to an ingenious double-layer structural design. Comparison between single-and multi-layer regenerators is conducted on the temperature span and temperature distribution characteristics by adopting layering MCMs with different Curie temperature points. The effects of crucial variables, including the model's structural parameter, operating parameter, MCM type, and arrangement, are discussed in detail.
APPLIED THERMAL ENGINEERING
(2023)
Article
Engineering, Chemical
Bo Yu, Fei Wang, Hua Liu, Zhiping Zhang, Yuhui Chen
Summary: This paper investigates the distribution of losses in the motor of an air compressor with air foil bearing, and proposes targeted design measures for heat dissipation. Through modeling and experimental verification, the loss distribution of the motor at different speeds is obtained. The results show that stator core loss and air friction loss are the main sources of losses, accounting for 55.64% and 29% of the total losses, respectively. These conclusions can effectively guide the heat dissipation design of high-speed air compressor motors with air foil bearing.
Article
Engineering, Chemical
Yang Yu, Kai Wang, Yurong Zhao, Qicheng Chen, Nanhang Dong
Summary: The effects of magnetic fields on the flow and heat transfer of nanofluids were investigated, and it was found that applying a magnetic field can increase the heat transfer coefficients of Cu-H2O nanofluids. Moreover, both the heat transfer coefficients and the Nusselt numbers increase with the increment of magnetic field intensities.
Article
Multidisciplinary Sciences
Ekrem Aydiner
Summary: This study investigates the quantum Szilard engine operating under a fractional power-law potential, proposing that it works in a Stirling-like cycle. Numerical computations of work and efficiency for various power-law potentials reveal positive results, indicating the potential of this simple engine. The discussion highlights the significance of fractional dynamics in physics and suggests the inclusion of fractional calculus in the fields of quantum information and thermodynamics.
SCIENTIFIC REPORTS
(2021)
Article
Thermodynamics
Zichan Xie, Haichao Wang, Pengmin Hua, Risto Lahdelma
Summary: This study introduces a novel and efficient method for dynamic thermal modelling of district heating pipes. The method uses discrete event simulation to track water frontiers and reduces computational complexity. The proposed model accurately computes outlet water temperature, temperature profile along the pipe, and heat loss. The model was validated against real measurements and showed accurate predictions.
Article
Mechanics
M. H. Faruk, M. Ferdows, E. E. Tzirtzilakis
Summary: Magnetic hyperthermia can be regulated in the blood by using magnetic nanoparticles and changing the nature of the magnetic field. This research examines the effects of uniform and non-uniform magnetic fields on bio-magnetic fluid and nano-bio-magnetic fluid under hyperthermia. The study shows that a uniform magnetic field increases temperature locally but decreases the overall temperature, while a non-uniform field decreases both local maximum and average blood temperature.
Article
Engineering, Civil
Shenghao Nan, Jie Ren, Feng Ni, Lei Zhang, Xianfeng He
Summary: This paper establishes a saturated-unsaturated flow-heat coupling model of embankment dams and compares its accuracy under different thermal conductivity empirical models (TCEMs). The Chung and Horton (1987) model shows better simulation effects, and the flow-heat coupling model is further improved by modifying the COMSOL built-in equation. The improved model is used to numerically simulate the concentrated leakage of embankment dams under dynamic water levels, showing positive correlation between flow velocity, pressure, and water level change.
JOURNAL OF HYDROLOGY
(2022)
Article
Engineering, Electrical & Electronic
Carlos Imbaquingo, Christian Bahl, Andrea R. Insinga, Rasmus Bjork
Summary: This article presents an elliptically shaped electromagnetic vibration energy harvester that can tune the resonance frequency easily. The harvester consists of a free-to-move ring-shaped permanent magnet, elliptically distributed cube magnets in a fixed holder, and two coil windings above and below the harvester. When subjected to vibrations, the ring magnet moves until it is pushed back by the magnetic force from the fixed cube magnets, inducing an electromagnetic force on the fixed coils. Experimental results show that the harvester has two resonant frequencies at 4.5 Hz and 7 Hz, generating around 1.5 mW of power.
SENSORS AND ACTUATORS A-PHYSICAL
(2023)
Article
Automation & Control Systems
Erik Holmen Olofsson, Michael Roland, Jon Spangenberg, Ninna Halberg Jokil, Jesper Henri Hattel
Summary: Mixing in extrusion is crucial for achieving consistent and high-quality extrudates, and residence time is a key measure of mixing performance. This study introduces a new CFD model that characterizes the extruder fill length and residence time distribution in a starve-fed extruder, including free surface tracking. The model is validated through laboratory tests and shows the impact of considering the partially filled extruder, rather than assuming it to be flooded, on residence time distribution. The results demonstrate the ability to fit simulation results to simpler analytical models, highlighting the importance of including the entire extrusion system for accurate predictions in starve-fed extrusion systems.
INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY
(2023)
Article
Materials Science, Multidisciplinary
Stefan Pollok, Nataniel Olden-Jorgensen, Peter Stanley Jorgensen, Rasmus Bjork
Summary: To retrieve valuable magnetic field information in high resolution, a generative adversarial network (GAN) structure is used to predict magnetic field values at a random point from a few point measurements. The trained generator can achieve a mean reconstruction test error of 6.45% when a large single coherent region of field points is missing, and 10.04% when only a few point measurements in space are available. Compared to conventional methods, such as linear interpolation, splines, and biharmonic equations, this approach performs better by a factor of two. Results are verified on an experimentally validated magnetic field.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Rasmus Bjork, Andrea Roberto Insinga
Summary: We investigate the effects of magnetic and geometric microscopic properties on the coercivity and maximum energy product of NdFeB permanent magnets. Our findings indicate that the easy axis orientation and grain boundary width have the largest influence on both coercivity and maximum energy product. In addition, we observe that the exchange constant only weakly affects the maximum energy product. This analysis helps to clarify the factors contributing to the reduction of coercivity and maximum energy product, known as Brown's paradox.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2023)
Article
Acoustics
P. Holm, C. Imbaquingo, B. P. Mann, R. Bjork
Summary: This paper discusses an electromagnetic energy harvester composed of a tube with fixed magnets and coils, and a floating dumbbell structure with magnets. The experimental characterization shows that the harvester can produce maximum power within a certain frequency range, and exhibits a softening resonator response and two resonance peaks.
JOURNAL OF SOUND AND VIBRATION
(2023)
Article
Thermodynamics
Alberto Santi, Mohamad Bayat, Jesper Hattel
Summary: Metal additive manufacturing (MAM) has seen significant growth in production performance and knowledge, but production defects are still a challenge due to the temperature development and residual stresses during printing. This study describes the modeling techniques of MAM, with a focus on thermomechanical modeling. Flash Heating (FH) and Sequential Flash Heating (SFH) methods show promise in providing reliable results in a short simulation time. Four case studies are presented and validated, and it is envisioned that FH and SFH methods can be part of a multi-scale, multi-physics modeling framework.
JOURNAL OF THERMAL STRESSES
(2023)
Article
Engineering, Chemical
Michael Sandberg, Jesper H. Hattel, Jon Spangenberg
Summary: Resin-injection pultrusion (RIP) utilizes high resin pressure for fast resin impregnation. Understanding flow-induced fiber compaction is important due to deformation caused by the injection process. This paper presents a numerical framework analyzing flow-induced fiber compaction and its effects on non-isothermal material flow in an industrial RIP process, with the result showing reduced flow resistance and improved resin impregnation due to fiber compaction. The research also highlights the influence of other factors such as fiber volume fraction and resin viscosity on the process.
TRANSPORT IN POROUS MEDIA
(2023)
Article
Chemistry, Multidisciplinary
Alireza Mollaei Ardestani, Ghasem Azamirad, Yasin Shokrollahi, Matteo Calaon, Jesper Henri Hattel, Murat Kulahci, Roya Soltani, Guido Tosello
Summary: Injection molding is a crucial process for mass production of plastic parts. Researchers have been focusing on predicting defects and optimizing process parameters to avoid them. Blush, a common defect near the gate, was studied in this research. Design of experiments, finite element analysis, and ANOVA were used to investigate eight design parameters with impact on blush formation. Machine learning methods including artificial neural networks, their combination with genetic algorithms, and particle swarm optimization were applied for efficient predictive modeling. Among them, basic artificial neural network achieved the closest predictions with an average accuracy error of 1.3%. ANOVA and genetic algorithm were utilized for process parameter optimization, resulting in significant reduction of blush defect area.
APPLIED SCIENCES-BASEL
(2023)
Article
Engineering, Manufacturing
W. E. Alphonso, M. Baier, S. Carmignato, J. H. Hattel, M. Bayat
Summary: Meso-scale, multi-physics simulations of metal additive manufacturing (MAM) processes are used to study the impacts of material/process-related uncertainties on the heat transfer conditions within the melt pool. The study investigates the effects of recoil pressure at different laser linear energy densities (LED) and laser beam sizes, as well as the influence of different capillary forces on the melt pool shape and size. The findings indicate a threshold LED below which the melt pool shape is not affected by the recoil pressure and is governed by the Marangoni effect.
JOURNAL OF MANUFACTURING PROCESSES
(2023)
Review
Energy & Fuels
Arindom Chatterjee, Carlos Nunez Lobato, Haiwu Zhang, Achilles Bergne, Vincenzo Esposito, Shinhee Yun, Andrea Roberto Insinga, Dennis Valbjorn Christensen, Carlos Imbaquingo, Rasmus Bjork, Hamsa Ahmed, Mariam Ahmad, Chun Yuen Ho, Morten Madsen, Jixi Chen, Poul Norby, Francesco Maria Chiabrera, Felix Gunkel, Ziwei Ouyang, Nini Pryds
Summary: Internet-of-thing (IoT) refers to a network of devices that collect and share data with each other through the internet, enabling access to raw information and facilitating intelligent decision making. With billions of IoT devices deployed, the challenge lies in creating self-powered units that can generate sufficient energy from ambient sources. This review paper discusses the recent progress in materials and device development for power and energy management in IoT applications, providing a comprehensive overview for new researchers and addressing challenges for those already in the field.
JOURNAL OF PHYSICS-ENERGY
(2023)
Article
Physics, Applied
Thierry Desire Pomar, Adrianna Elzbieta Frackowiak, Ricci Erlandsen, Dennis Valbjorn Christensen, Rasmus Bjork
Summary: This article studies the effect of manipulating the shape of the outer boundary of a magnetometer on its performance. The results show that adding a constriction between voltage or current probes increases the maximum sensitivity of the device by 70%, and shifting the boundary shape from circular to elliptical increases it by 300%. Additionally, breaking the horizontal symmetry of the device can lead to finite zero-field sensitivity. These findings highlight the significant impact of the outer boundary on device performance, paving the way for shape optimization in designing sensitive magnetometers.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Ricci Erlandsen, Thierry Desire Pomar, Lior Kornblum, Nini Pryds, Rasmus Bjork, Dennis Christensen
Summary: This study systematically investigates the interplay between material geometry and magnetoresistance effects in EMR devices. The sensitivity of EMR devices is inversely proportional to carrier density, and the magnetoresistance saturates at low carrier densities. High mobilities and low interface resistances are crucial for achieving high magnetoresistance. Encapsulated graphene and InSb are promising candidates for achieving high magnetoresistance in EMR devices at room temperature.
JOURNAL OF PHYSICS-MATERIALS
(2023)
Proceedings Paper
Polymer Science
Michael Roland Larsen, Simone Christensen, Inge Aagaard, Adrian Defante, Tobias Ottsen, Jesper Henri Hattel, Jon Spangenberg
Summary: In this paper, a Taguchi DOE is conducted to study the homogeneity of adhesive materials using a pilot-scale twin-sigma-blade mixer. The results indicate that purifying the particles has a significant positive impact on the homogeneity of the adhesive barriers.
PROCEEDINGS OF THE 36TH CONFERENCE OF THE POLYMER PROCESSING SOCIETY, PPS36
(2023)
Article
Physics, Applied
Kun Wang, Johannes T. B. Overvelde, Kurt Engelbrecht, Rasmus Bjork, Christian R. H. Bahl
Summary: Passive fluid flow in high-strain regenerators is studied using a numerical model and experimental methods. Hyperelastic models and finite-element simulations are used to predict the volume changes of the regenerators under applied strains of 200%-600%, and the results are validated through experiments.
APPLIED PHYSICS LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Jixi Chen, Alessandro Palliotto, Shinhee Yun, Dennis Valbjorn Christensen, Vincenzo Esposito, Nini Pryds
Summary: In this study, a method that combines synthesis optimization with a post-lithiation process is introduced to enhance the ionic conductivity of LLZO electrolyte. By compensating lithium loss and stabilizing the LLZO phase, the ionic conductivity is amplified by more than three orders of magnitude. The research also determines the optimal process conditions for the highest conductivity.
MATERIALS ADVANCES
(2023)
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)
