Article
Thermodynamics
Georges El Achkar, Bin Liu, Rachid Bennacer
Summary: In this study, the effects of operating conditions on the energy efficiency of a reciprocating room temperature magnetic refrigerator were experimentally investigated. An optimal operating point was identified to optimize the refrigeration performance.
CASE STUDIES IN THERMAL ENGINEERING
(2022)
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
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
Wenshuai Zheng, Jun Shen, Zhenxing Li, Xinqiang Gao, Ke Li, Hongmei Huang, Peng Hai, Zhaojun Mo, Wei Dai
Summary: A hybrid refrigerator that combines the GM refrigeration effect with the magnetic refrigeration effect has been built, and a new magnetic regenerator filled with Pb, ErNi and EuTi0.875Al0.125O3 has been constructed to improve the cooling performance. The new magnetic regenerator filled with EuTi0.875Al0.125O3 could obtain a lower cooling temperature and a larger cooling power in the hybrid refrigerator, as predicted numerically and confirmed by experimental tests.
APPLIED THERMAL ENGINEERING
(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
Thermodynamics
M. Masche, J. Liang, K. Engelbrecht, C. R. H. Bahl
Summary: An experimental rotary magnetocaloric prototype utilizing active magnetic regeneration was presented as an alternative to traditional cooling systems. The prototype achieved efficient cooling using gadolinium spheres and water mixed with ethylene glycol as the refrigerant and heat transfer fluid, respectively. Operating near room temperature, the system demonstrated cooling powers exceeding 800 W at 1.4 Hz, comparable to existing magnetocaloric devices.
APPLIED THERMAL ENGINEERING
(2022)
Article
Thermodynamics
Jierong Liang, Kurt Engelbrecht, Kaspar K. Nielsen, Konrad Loewe, Hugo Vieyra, Alexander Barcza, Christian R. H. Bahl
Summary: This study successfully improved the stability of magnetocaloric materials by shaping La(Fe,Si,Mn)(13)H-y into a regenerator with triangular microchannels, and comprehensively characterized its heat transfer and cooling performance. It shows promising potential for enhancing the operational coefficient of performance in specific magnetic refrigerators.
APPLIED THERMAL ENGINEERING
(2021)
Article
Thermodynamics
Gokmen Peker, Derya Burcu Ozkan
Summary: This study investigates the heat transfer performance of a hot-wall condenser, which is affected by design parameters. The variation of pipe section form (O/D), a previously unexamined design parameter, was used. Twelve different condenser samples were manufactured with specified design parameters, and a simulation model was designed for comparison with experimental results. The results showed significant effects of the design parameters on the heat transfer rate of the condenser, including increases in heat transfer rate with larger condenser pipe diameter and variations in pipe pitch.
APPLIED THERMAL ENGINEERING
(2023)
Article
Thermodynamics
Tu Thien Ngo, Ngoc Vi Nguyen, Dong-Wook Oh
Summary: This study investigates the heat transfer performance of a flat-plate type rotary regenerator made of polymer or metal through a numerical simulation. The effects of the matrix material, flow channel and wall thicknesses on the temperature profiles were analyzed. Correlations of Nusselt number as functions of Reynolds number, non-dimensional matrix wall thickness, and non-dimensional thermal mass parameters were developed.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Thermodynamics
Johan Augusto Bocanegra, Federico Scarpa, Luca Antonio Tagliafico
Summary: This study discusses the evaluation methods for the static performance of an Active Magnetic Regenerator Refrigerator (AMRR). In real-world operations, thermal connection through heat exchangers and the absence of imposed temperature values may lead to suboptimal performance even after adjusting control parameters. The study compares the use of different heat exchangers or imposing temperature spans to evaluate the device's performance.
INTERNATIONAL JOURNAL OF REFRIGERATION
(2023)
Article
Thermodynamics
Zhenxing Li, Ke Li, Xiaohui Guo, Xinqiang Gao, Wei Dai, Maoqiong Gong, Jun Shen
Summary: The timing between magnetic field profile and fluid flow profile significantly affects the performance of a rotary magnetic refrigerator. It was found that, under the same utilization factor and frequency, the longer the flow time, the larger the temperature span. Despite being limited by motor power, a relatively high cooling power was still achieved.
APPLIED THERMAL ENGINEERING
(2021)
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
Energy & Fuels
Huanguang Wang, Yunhao Bao, Yuming Tang, Meng Liu, Bilin Zhang, Shuai Zhu, Zhonghao Rao
Summary: The relative thickness e plays a crucial role in the heat storage efficiency and heat transfer coefficient of parallel-plate regenerators (PPR), and by comprehensively considering e, the performance of PPR can be optimized.
INTERNATIONAL JOURNAL OF ENERGY RESEARCH
(2021)
Article
Thermodynamics
Jongmin Choi, Seungyeon Lee, Min Soo Kim
Summary: This study investigates the effect of non-aligned and aligned irregular gadolinium particles on the performance of a magnetic refrigeration system. X-ray computed tomography reveals that the aligned particles are arranged in parallel to the flow direction, while the non-aligned particles are randomly located. The aligned particles result in a smaller pressure drop and friction factor compared to the non-aligned ones. Furthermore, the coefficient of performance of the aligned particles is significantly improved at different operating frequencies.
ENERGY CONVERSION AND MANAGEMENT
(2023)
Article
Thermodynamics
Jongmin Choi, Seungyeon Lee, Min Soo Kim
Summary: In this research, a new testbed for a magnetic refrigeration system at room temperature was proposed and experimentally analyzed. The testbed demonstrated good performance under different operating conditions and the parallel mode was found to provide a stable temperature span, especially under thermal load conditions.
ENERGY CONVERSION AND MANAGEMENT
(2022)
Article
Materials Science, Multidisciplinary
Braulio Beltran-Pitarch, Benny Guralnik, Neetu Lamba, Andreas R. Stilling-Andersen, Lars Norregaard, Torben M. Hansen, Ole Hansen, Nini Pryds, Peter F. Nielsen, Dirch H. Petersen
Summary: In order to develop materials with higher thermoelectric efficiency, a new method based on micro four-point probe (M4PP) was developed to determine the thermal diffusivity of a bulk material using the phase delay of the second harmonic voltage. The method was tested on two relevant thermoelectric materials, skutterudite and bismuth telluride, and showed good agreement with independent estimates. The M4PP method also demonstrated the ability to characterize materials with nonuniform and erratic electrical resistivity, such as bismuth telluride.
MATERIALS TODAY PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Hang Li, Walber H. Brito, Eduardo B. Guedes, Alla Chikina, Rasmus T. Dahm, Dennis V. Christensen, Shinhee Yun, Francesco M. Chiabrera, Nicholas C. Plumb, Ming Shi, Nini Pryds, Milan Radovic
Summary: Relatively simple surface preparation can reconstruct the 2D electron gas (2DEG) at the SrTiO3 surface, leading to a Lifshitz-like transition. Experimental methods combined with ab initio calculations reveal that the modulation of the surface band structures can be achieved via transforming the chemical composition at the atomic scale. Additionally, ARPES experiments demonstrate that vacuum ultraviolet light can effectively alter the band renormalization of the 2DEG system and control the electron-phonon interaction.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Dae-Sung Park, Aurora Diana Rata, Rasmus Tindal Dahm, Kanghyun Chu, Yulin Gan, Igor Maznichenko, Sergey Ostanin, Felix Trier, Hionsuck Baik, Woo Seok Choi, Chel-Jong Choi, Young Heon Kim, Gregory Jon Rees, Haflidi Petur Gislason, Pawel Adam Buczek, Ingrid Mertig, Mihai Adrian Ionescu, Arthur Ernst, Kathrin Doerr, Paul Muralt, Nini Pryds
Summary: Complex oxide heterointerfaces offer numerous physical properties and functionalities, leading to emerging technologies. Vertically aligned nanostructure (VAN) films, formed through a self-assembling bottom-up deposition method, show great promise in terms of structural flexibility and property tunability. This study introduces a new approach of bottom-up self-assembly using a mixture of 2D layer-by-layer film growth and 3D VAN film growth. The resulting two-phase nanocomposite thin films, based on LaAlO3:LaBO3, grown on a lattice-mismatched SrTiO3001 (001) single crystal, exhibit coexistence of multiple interfacial properties, including 2D electron gas and magnetic anisotropy. This approach offers multidimensional film heterostructures, enriching emergent phenomena for multifunctional applications.
ADVANCED MATERIALS
(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
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)
Review
Chemistry, Multidisciplinary
Haiwu Zhang, Milica Vasiljevic, Achilles Bergne, Dae-Sung Park, Andrea R. Insinga, Shinhee Yun, Vincenzo Esposito, Nini Pryds
Summary: Complex oxides with diverse functionalities are crucial for cutting-edge electronics, energy, and information technologies. This review explores how to engineer thermodynamic variables to break the symmetry of centrosymmetric oxides and achieve/improve their electromechanical properties. The mechanisms used to break the inherent symmetry of conventional materials and discover novel applications are discussed. Accessing hidden phases could uncover opportunities for exotic properties like piezoelectricity and pyroelectricity. This review not only reports on engineering nonpolar oxides but also has implications for manipulating polar functional materials for better performance.
ADVANCED MATERIALS INTERFACES
(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
Materials Science, Multidisciplinary
Victor Rosendal, Walber H. Brito, Milan Radovic, Alla Chikina, Mads Brandbyge, Nini Pryds, Dirch H. Petersen
Summary: This study maps the energy landscape of octahedral tilting in Strontium niobate using density functional theory calculations, and finds that compressive strain induces tilting around the out-of-plane axis, while tensile strain induces tilting around the in-plane axes. The competition between in-phase and out-of-phase tilting in SrNbO3 allows for tuning the thermoelectric and optical properties. The study also shows how the tilt angle and mode affect the Seebeck coefficient and the plasma frequency due to changes in the band structure.
PHYSICAL REVIEW MATERIALS
(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
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)
Article
Engineering, Electrical & Electronic
Dennis Christensen, Regina Dittmann, Bernabe Linares-Barranco, Abu Sebastian, Manuel Le Gallo, Andrea Redaelli, Stefan Slesazeck, Thomas Mikolajick, Sabina Spiga, Stephan Menzel, Ilia Valov, Gianluca Milano, Carlo Ricciardi, Shi-Jun Liang, Feng Miao, Mario Lanza, Tyler J. Quill, Scott T. Keene, Alberto Salleo, Julie Grollier, Danijela Markovic, Alice Mizrahi, Peng Yao, J. Joshua Yang, Giacomo Indiveri, John Paul Strachan, Suman Datta, Elisa Vianello, Alexandre Valentian, Johannes Feldmann, Xuan Li, Wolfram H. P. Pernice, Harish Bhaskaran, Steve Furber, Emre Neftci, Franz Scherr, Wolfgang Maass, Srikanth Ramaswamy, Jonathan Tapson, Priyadarshini Panda, Youngeun Kim, Gouhei Tanaka, Simon Thorpe, Chiara Bartolozzi, Thomas A. Cleland, Christoph Posch, Shihchii Liu, Gabriella Panuccio, Mufti Mahmud, Arnab Neelim Mazumder, Morteza Hosseini, Tinoosh Mohsenin, Elisa Donati, Silvia Tolu, Roberto Galeazzi, Martin Ejsing Christensen, Sune Holm, Daniele Ielmini, N. Pryds
Summary: This article introduces the characteristics and advantages of von Neumann architecture and neuromorphic computing systems. While traditional von Neumann architecture is powerful, it has high power consumption and cannot handle complex data. Neuromorphic computing systems, inspired by biological concepts, can achieve lower power consumption for storing and processing large amounts of digital information. The aim of this article is to provide perspectives on the current state and future challenges in the field of neuromorphic technology, and to provide a concise yet comprehensive introduction and future outlook for readers.
NEUROMORPHIC COMPUTING AND ENGINEERING
(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)
