Article
Energy & Fuels
Bongseok Kim, Jihwan An, Min K. Sim
Summary: This paper introduces a novel framework that utilizes hierarchical reinforcement learning (HRL) to optimize the temperature control policy of refrigerators under Time-of-Use (ToU) electricity pricing. The proposed method outperforms conventional control methods and standard reinforcement learning approaches, achieving significant cost reductions.
SUSTAINABLE ENERGY GRIDS & NETWORKS
(2023)
Article
Thermodynamics
Debashis Panda, Manoj Kumar, Ashok K. Satapathy, Sunil K. Sarangi
Summary: This paper investigates the simultaneous influence of various factors on the cooling capacity and coefficient of performance of a single-stage orifice pulse tube refrigerator. By using numerical and ANN models, as well as sensitivity analysis, the study optimizes the regression equation to maximize the functional relationship between design variables and responses. Experimental investigations within the optimal range of inputs show improvements in cooling power and COP after optimization.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2021)
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
Physics, Applied
Junyi Wang, Youlin Wang, Xiaohang Chen, Jincan Chen, Shanhe Su
Summary: In this study, a model of a thermophotovoltaic device that combines a near-field thermal emitter and a hot-carrier solar cell is established. The study introduces the concept of fluctuating electromagnetic near-field theory for radiative thermal transport and Landauer's formula for carrier extraction. The expressions for efficiency and power output are derived, and the impact of voltage and extraction energy of energy selective contacts on the device performance is revealed. The results demonstrate that exploiting radiation between the emitter and the cell and extracting carriers through electron tunneling effects can significantly enhance the efficiency of the proposed device.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Multidisciplinary
Rodolfo R. Soldati, Durga B. R. Dasari, Jor Wrachtrup, Eric Lutz
Summary: The thermodynamic performance of a minimal three-qubit heat-bath algorithmic cooling refrigerator is investigated theoretically and experimentally. The coefficient of performance, cooling power, and polarization of the target qubit are analytically computed for an arbitrary number of cycles, considering realistic experimental imperfections. The fundamental upper bounds of these values are determined in the ideal reversible limit, and it is shown that these values can be approached experimentally using a system of three qubits in a nitrogen-vacancy center in diamond.
PHYSICAL REVIEW LETTERS
(2022)
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
Physics, Applied
Michal Kloc, Kurt Meier, Kimon Hadjikyriakos, Gernot Schaller
Summary: In this study, it is demonstrated that the lower levels of a large-spin network can act as a quantum-absorption refrigerator with a cooling current scaling quadratically with the number of spins. This scaling behavior is also observed for noise and entropy production rate.
PHYSICAL REVIEW APPLIED
(2021)
Article
Multidisciplinary Sciences
C. R. Lawson, A. T. Jones, W. Kockelmann, S. J. Horney, O. Kirichek
Summary: The invention of the He-3/He-4 dilution refrigerator has greatly advanced experimental ultra-low temperature physics. Dilution refrigerators are crucial for creating ultra-low temperature environments for various experiments. The development of dilution refrigeration technology relies on a thorough understanding of the quantum mechanical processes in liquid helium at ultra-low temperatures. In this study, the researchers used neutron radiography to directly observe the operational dilution refrigerator, providing important insights into its behavior and failure modes. This method has the potential to significantly contribute to the research and development of advanced dilution refrigerators.
SCIENTIFIC REPORTS
(2022)
Article
Engineering, Environmental
Ping Zhu, Shuangshuang Gong, Mingqiang Deng, Bin Xia, Yazheng Yang, Jiakang Tang, Guangren Qian, Fang Yu, Ashantha Goonetilleke, Xiaowei Li
Summary: This study investigates the degradation of waste refrigerator polyurethane (WRPU) by mealworms and reveals that mealworms can ingest and degrade WRPU, causing changes in its composition and thermal stability. Carbon balance analysis confirms partial mineralization of ingested WRPU. The presence of impurities and odor in WRPU affects the appetite and nutrient intake of mealworms. WRPU also affects the gut microorganism of mealworms.
FRONTIERS OF ENVIRONMENTAL SCIENCE & ENGINEERING
(2023)
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
Ankuo Zhang, Yinan Han, Shuling Guo, Renchao Tong
Summary: This study systematically investigated the cooling performance of a coaxial PTR and its effect on reject temperature, and found that as the reject temperature increases, each position in the PTR will exhibit different degrees of phase hysteresis, resulting in less loss of major components and reduced enthalpy flow at the cold end of the pulse tube.
APPLIED THERMAL ENGINEERING
(2023)
Article
Thermodynamics
Islam A. Ramadan, Helene Bailliet, Gaelle Poignand, David Gardner
Summary: Thermoacoustic refrigeration technology offers a green alternative to conventional vehicle refrigeration systems by using environmentally friendly inert gases instead of chemical refrigerants. A new compact thermoacoustic refrigerator design incorporating two electroacoustic components and one thermoacoustic core is described, with testing confirming the proposed thermal design methodology.
APPLIED THERMAL ENGINEERING
(2021)
Article
Energy & Fuels
Muluken Z. Z. Getie, Francois Lanzetta, Sylvie Begot, Bimrew T. T. Admassu, Steve Djetel-Gothe
Summary: In this study, a nonideal modified simple numerical model was used to investigate the effects of parameters on the cooling performance of a moderate temperature Stirling refrigerator, and an optimized design was proposed. The results showed that by optimizing the parameters, the cold production and COP could be significantly improved, with a 48% to 60% increase in cold production and a 30% to 40% increase in COP compared to the existing design.
INTERNATIONAL JOURNAL OF ENERGY RESEARCH
(2023)
Article
Thermodynamics
M. Masche, J. Liang, K. Engelbrecht, C. R. H. Bahl
Summary: Magnetocaloric energy conversion devices have the potential to reduce refrigerant leakage emissions, but their efficiency is lower than vapor compression systems. The study experimentally demonstrates the advantage of modulating the cooling capacity of an active magnetic regenerator prototype for the first time. By adjusting the cycle frequency and volumetric flow rate, the device achieves higher efficiency and competitive performance with traditional vapor compression systems.
INTERNATIONAL JOURNAL OF REFRIGERATION
(2023)
Article
Instruments & Instrumentation
Jiaojie Yan, Jianing Yao, Vladimir Shvarts, Rui-Rui Du, Xi Lin
Summary: A temperature below 100 mu K is achieved using a customized cryogen-free dilution refrigerator with a copper-nuclear demagnetization stage. The lowest temperature of conduction electrons is measured by a pulsed platinum nuclear magnetic resonance thermometer, and can remain below 100 mu K for over 10 hours. The demagnetization magnetic field and research magnetic field can be controlled independently, provided by a coaxial room-temperature-bore cryogen-free magnet.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2021)
Article
Physics, Multidisciplinary
Senaida Hernandez-Santana, Arnau Riera, Karen V. Hovhannisyan, Marti Perarnau-Llobet, Luca Tagliacozzo, Antonio Acin
NEW JOURNAL OF PHYSICS
(2015)
Article
Physics, Multidisciplinary
Marcus Huber, Marti Perarnau-Llobet, Karen V. Hovhannisyan, Paul Skrzypczyk, Claude Kloeckl, Nicolas Brunner, Antonio Acin
NEW JOURNAL OF PHYSICS
(2015)
Article
Physics, Fluids & Plasmas
David Edward Bruschi, Marti Perarnau-Llobet, Nicolai Friis, Karen V. Hovhannisyan, Marcus Huber
Article
Physics, Multidisciplinary
Marti Perarnau-Llobet, Karen V. Hovhannisyan, Marcus Huber, Paul Skrzypczyk, Nicolas Brunner, Antonio Acin
Article
Physics, Multidisciplinary
Marti Perarnau-Llobet, Elisa Baumer, Karen V. Hovhannisyan, Marcus Huber, Antonio Acin
PHYSICAL REVIEW LETTERS
(2017)
Article
Physics, Multidisciplinary
Alejandro Pozas-Kerstjens, Eric G. Brown, Karen V. Hovhannisyan
NEW JOURNAL OF PHYSICS
(2018)
Article
Physics, Multidisciplinary
Karen Hovhannisyan, Alberto Imparato
NEW JOURNAL OF PHYSICS
(2019)
Article
Physics, Multidisciplinary
Kang-Da Wu, Elisa Baumer, Jun-Feng Tang, Karen Hovhannisyan, Marti Perarnau-Llobet, Guo-Yong Xiang, Chuan-Feng Li, Guang-Can Guo
PHYSICAL REVIEW LETTERS
(2020)
Article
Physics, Multidisciplinary
Felipe Barra, Karen Hovhannisyan, Alberto Imparato
Summary: This paper introduces and studies a cyclic battery-charger quantum device that is in thermal equilibrium or in a ground state during the charge storing stage. The study shows that the extracted energy and thermodynamic efficiency can be enhanced by operating the cycle close to the quantum phase transition point. The performance of the device is further optimized by leveraging the correlations between the battery and the charger.
NEW JOURNAL OF PHYSICS
(2022)
Article
Quantum Science & Technology
Karen V. Hovhannisyan, Somayyeh Nemati, Carsten Henkel, Janet Anders
Summary: When two initially thermal many-body systems start to interact strongly, their transient states quickly become non-Gibbsian, even if the systems eventually equilibrate. To understand the structure during the transient regime, a refined notion of thermality called g-local is used. Numerical demonstration shows that for two harmonic lattices with long-range interactions, each lattice remains g-locally thermal at all times, including the transient regime. The equilibrium is described by the generalized Gibbs ensemble, with special treatment required for three-dimensional lattices due to their extended set of conserved charges. Comparison with the two-temperature model reveals the partial salvage of the model at strong coupling by adopting the concept of a g-local temperature.
Article
Multidisciplinary Sciences
Armen E. Allahverdyan, Karen Hovhannisyan, David Petrosyan
Summary: This proposal presents a dynamical model for the state symmetrization of two identical particles produced by independent sources in spacelike-separated events. The model suggests that initially distinguishable particles become indistinguishable as they collide, leading to a symmetrized state. The probability density of collision times can be estimated using quasi-classical methods or fully quantum mechanical considerations.
PROCEEDINGS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
(2021)
Article
Quantum Science & Technology
Karen Hovhannisyan, Mathias R. Jorgensen, Gabriel T. Landi, Alvaro M. Alhambra, Jonatan B. Brask, Marti Perarnau-Llobet
Summary: Accurate thermometry for quantum systems is crucial for technological advancement, but practical implementations often involve coarse-grained measurements. By utilizing tools from signal processing, we can achieve good temperature estimates even with a small number of outcomes. Our findings have implications for many-body systems and nonequilibrium thermometry, providing insights into optimal coarse-grained measurements and strategies for probe-based thermometry.
Article
Physics, Multidisciplinary
Karen Hovhannisyan, Felipe Barra, Alberto Imparato
PHYSICAL REVIEW RESEARCH
(2020)
Article
Materials Science, Multidisciplinary
Karen Hovhannisyan, Luis A. Correa
Article
Optics
Luis A. Correa, Marti Perarnau-Llobet, Karen V. Hovhannisyan, Senaida Hernandez-Santana, Mohammad Mehboudi, Anna Sanpera