The Experts below are selected from a list of 41466 Experts worldwide ranked by ideXlab platform
Ryyan M Khan - One of the best experts on this subject based on the ideXlab platform.
-
shockley queisser triangle predicts the Thermodynamic Efficiency limits of arbitrarily complex multijunction bifacial solar cells
Proceedings of the National Academy of Sciences of the United States of America, 2019Co-Authors: Muhammad A Alam, Ryyan M KhanAbstract:As monofacial, single-junction solar cells approach their fundamental limits, there has been significant interest in tandem solar cells in the presence of concentrated sunlight or tandem bifacial solar cells with back-reflected albedo. The bandgap sequence and Thermodynamic Efficiency limits of these complex cell configurations require sophisticated numerical calculation. Therefore, the analyses of specialized cases are scattered throughout the literature. In this paper, we show that a powerful graphical approach called the normalized "Shockley-Queisser (S-Q) triangle" (i.e., [Formula: see text]) is sufficient to calculate the bandgap sequence and Efficiency limits of arbitrarily complex photovoltaic (PV) topologies. The results are validated against a wide variety of specialized cases reported in the literature and are accurate within a few percent. We anticipate that the widespread use of the S-Q triangle will illuminate the deeper physical principles and design trade-offs involved in the design of bifacial tandem solar cells under arbitrary concentration and series resistance.
-
Thermodynamic Efficiency limits of classical and bifacial multi junction tandem solar cells an analytical approach
Applied Physics Letters, 2016Co-Authors: Muhammad A Alam, Ryyan M KhanAbstract:Bifacial tandem cells promise to reduce three fundamental losses (i.e., above-bandgap, below bandgap, and the uncollected light between panels) inherent in classical single junction photovoltaic (PV) systems. The successive filtering of light through the bandgap cascade and the requirement of current continuity make optimization of tandem cells difficult and accessible only to numerical solution through computer modeling. The challenge is even more complicated for bifacial design. In this paper, we use an elegantly simple analytical approach to show that the essential physics of optimization is intuitively obvious, and deeply insightful results can be obtained with a few lines of algebra. This powerful approach reproduces, as special cases, all of the known results of conventional and bifacial tandem cells and highlights the asymptotic Efficiency gain of these technologies.
Muhammad A Alam - One of the best experts on this subject based on the ideXlab platform.
-
shockley queisser triangle predicts the Thermodynamic Efficiency limits of arbitrarily complex multijunction bifacial solar cells
Proceedings of the National Academy of Sciences of the United States of America, 2019Co-Authors: Muhammad A Alam, Ryyan M KhanAbstract:As monofacial, single-junction solar cells approach their fundamental limits, there has been significant interest in tandem solar cells in the presence of concentrated sunlight or tandem bifacial solar cells with back-reflected albedo. The bandgap sequence and Thermodynamic Efficiency limits of these complex cell configurations require sophisticated numerical calculation. Therefore, the analyses of specialized cases are scattered throughout the literature. In this paper, we show that a powerful graphical approach called the normalized "Shockley-Queisser (S-Q) triangle" (i.e., [Formula: see text]) is sufficient to calculate the bandgap sequence and Efficiency limits of arbitrarily complex photovoltaic (PV) topologies. The results are validated against a wide variety of specialized cases reported in the literature and are accurate within a few percent. We anticipate that the widespread use of the S-Q triangle will illuminate the deeper physical principles and design trade-offs involved in the design of bifacial tandem solar cells under arbitrary concentration and series resistance.
-
shockley queisser triangle an elegant analytical tool for predicting the Thermodynamic Efficiency limits of multi junction tandem and bifacial cells with arbitrary concentration and series resistance
World Conference on Photovoltaic Energy Conversion, 2018Co-Authors: Muhammad A AlamAbstract:As monofacial, single junction solar cells approach their fundamental limits, there has been significant interest in tandem solar cells in the presence of concentrated sunlight or tandem bifacial solar cells with back-reflected albedo. The bandgap sequence and Thermodynamic Efficiency limits of these complex cell configurations generally require complicated numerical calculation. The analysis of specialized cases are scattered throughout the literature. In this paper, we show that a powerful graphical approach called the normalized “Shockley-Queisser Triangle (i.e. i mp = 1 – v mp ), is sufficient to calculate the bandgap sequence and Efficiency limits of arbitrary complex PV topologies. The results are validated against a wide variety of specialized cases reported in the literature and are accurate within a few percent. We anticipate that widespread use of the SQ-triangle will illuminate the deeper physical principles and design trade-offs involved in the design of tandem solar cells under arbitrary concentration and series resistance.
-
Thermodynamic Efficiency limits of classical and bifacial multi junction tandem solar cells an analytical approach
Applied Physics Letters, 2016Co-Authors: Muhammad A Alam, Ryyan M KhanAbstract:Bifacial tandem cells promise to reduce three fundamental losses (i.e., above-bandgap, below bandgap, and the uncollected light between panels) inherent in classical single junction photovoltaic (PV) systems. The successive filtering of light through the bandgap cascade and the requirement of current continuity make optimization of tandem cells difficult and accessible only to numerical solution through computer modeling. The challenge is even more complicated for bifacial design. In this paper, we use an elegantly simple analytical approach to show that the essential physics of optimization is intuitively obvious, and deeply insightful results can be obtained with a few lines of algebra. This powerful approach reproduces, as special cases, all of the known results of conventional and bifacial tandem cells and highlights the asymptotic Efficiency gain of these technologies.
Juan G Santiago - One of the best experts on this subject based on the ideXlab platform.
-
high water recovery and improved Thermodynamic Efficiency for capacitive deionization using variable flowrate operation
Water Research, 2019Co-Authors: Ashwin Ramachandran, Diego I Oyarzun, Steven A Hawks, Michael Stadermann, Juan G SantiagoAbstract:Water recovery is a measure of the amount of treated water produced relative to the total amount of water processed through the system, and is an important performance metric for any desalination method. Conventional operating methods for desalination using capacitive deionization (CDI) have so far limited water recovery to be about 50%. To improve water recovery for CDI, we here introduce a new operating scheme based on a variable (in time) flow rate wherein a low flow rate during discharge is used to produce a brine volume which is significantly less than the volume of diluent produced. We demonstrate experimentally and study systematically this novel variable flowrate operating scheme in the framework of both constant current and constant voltage charge-discharge modes. We show that the variable flowrate operation can increase water recovery for CDI to very high values of ∼90% and can improve Thermodynamic Efficiency by about 2- to 3-fold compared to conventional constant flowrate operation. Importantly, this is achieved with minimal performance reductions in salt removal, energy consumption, and volume throughput. Our work highlights that water recovery can be readily improved for CDI at very minimal additional cost using simple flow control schemes.
-
Thermodynamics of ion separation by electrosorption
Environmental Science & Technology, 2018Co-Authors: Ali Hemmatifar, Ashwin Ramachandran, Diego I Oyarzun, Juan G SantiagoAbstract:We present a simple, top-down approach for the calculation of minimum energy consumption of electrosorptive ion separation using variational form of the (Gibbs) free energy. We focus and expand on the case of electrostatic capacitive deionization (CDI). The theoretical framework is independent of details of the double-layer charge distribution and is applicable to any Thermodynamically consistent model, such as the Gouy–Chapman–Stern and modified Donnan models. We demonstrate that, under certain assumptions, the minimum required electric work energy is indeed equivalent to the free energy of separation. Using the theory, we define the Thermodynamic Efficiency of CDI. We show that the Thermodynamic Efficiency of current experimental CDI systems is currently very low, around 1% for most existing systems. We applied this knowledge and constructed and operated a CDI cell to show that judicious selection of the materials, geometry, and process parameters can lead to a 9% Thermodynamic Efficiency and 4.6 kT per...
-
Thermodynamics of ion separation by electrosorption
arXiv: Chemical Physics, 2018Co-Authors: Ali Hemmatifar, Ashwin Ramachandran, Diego I Oyarzun, Juan G SantiagoAbstract:We present a simple, top-down approach for the calculation of minimum energy consumption of electrosorptive ion separation using variational form of the (Gibbs) free energy. We focus and expand on the case of electrostatic capacitive deionization (CDI), and the theoretical framework is independent of details of the double-layer charge distribution and is applicable to any Thermodynamically consistent model, such as the Gouy-Chapman-Stern (GCS) and modified Donnan (mD) models. We demonstrate that, under certain assumptions, the minimum required electric work energy is indeed equivalent to the free energy of separation. Using the theory, we define the Thermodynamic Efficiency of CDI. We explore the Thermodynamic Efficiency of current experimental CDI systems and show that these are currently very low, less than 1% for most existing systems. We applied this knowledge and constructed and operated a CDI cell to show that judicious selection of the materials, geometry, and process parameters can be used to achieve a 9% Thermodynamic Efficiency (4.6 kT energy per removed ion). This relatively high value is, to our knowledge, by far the highest Thermodynamic Efficiency ever demonstrated for CDI. We hypothesize that Efficiency can be further improved by further reduction of CDI cell series resistances and optimization of operational parameters.
-
porous glass electroosmotic pumps design and experiments
Joint International Conference on Information Sciences, 2003Co-Authors: Shuhuai Yao, David Hertzog, Shulin Zeng, James C Mikkelsen, Juan G SantiagoAbstract:An analytical model for electroosmotic flow rate, total pump current, and Thermodynamic Efficiency reported in a previous paper has been applied as a design guideline to fabricate porous-structure EO pumps. We have fabricated sintered-glass EO pumps that provide maximum flow rates and pressure capacities of 33 ml/min and 1.3 atm, respectively, at applied potential 100 V. These pumps are designed to be integrated with two-phase microchannel heat exchangers with load capacities of order 100 W and greater. Experiments were conducted with pumps of various geometries and using a relevant, practical range of working electrolyte ionic concentration. Characterization of the pumping performance are discussed in the terms of porosity, tortuosity, pore size, and the dependence of zeta potential on bulk ion density of the working solution. The effects of pressure and flow rate on pump current and Thermodynamic Efficiency are analyzed and compared to the model prediction. In particular, we explore the important tradeoff between increasing flow rate capacity and obtaining adequate Thermodynamic Efficiency. This research aims to demonstrate the performance of EOF pump systems and to investigate optimal and practical pump designs. We also present a gas recombination device that makes possible the implementation of this pumping technology into a closed-flow loop where electrolytic gases are converted into water and reclaimed by the system.
Rahul R Bhosale - One of the best experts on this subject based on the ideXlab platform.
-
Thermodynamic Efficiency analysis of zinc oxide based solar driven thermochemical h2o splitting cycle effect of partial pressure of o2 thermal reduction and h2o splitting temperatures
International Journal of Hydrogen Energy, 2018Co-Authors: Rahul R BhosaleAbstract:Abstract In this paper, the Thermodynamic Efficiency analysis of ZnO-based solar-driven thermochemical H2O splitting cycle is performed and compared with the SnO2-based H2O splitting cycle. The HSC Chemistry 7.1 software is used for this analysis and effects of thermal reduction ( T H ) and water splitting temperature ( T L ) on various Thermodynamic parameters associated with the ZnO-based H2O splitting cycle are explored. The Thermodynamic equilibrium compositions allied with the ZnO reduction and re-oxidation of Zn via H2O splitting reaction are identified by varying the T H , T L , and P O 2 in the inert gas. The Efficiency analysis indicates that the highest cycle and solar-to-fuel energy conversion Efficiency equal to 41.1 and 49.5% can be achieved at T H = 1340 K and T L = 650 K. Both efficiencies can be increased further by more than 10% via employing heat recuperation (50%). Based on the cycle and solar-to-fuel energy conversion Efficiency values, the ZnO-based H2O splitting cycle seems to be more attractive than SnO2-based H2O splitting cycle.
Mikhail Prokopenko - One of the best experts on this subject based on the ideXlab platform.
-
Thermodynamic Efficiency of interactions in self organizing systems
Entropy, 2021Co-Authors: Ramil Nigmatullin, Mikhail ProkopenkoAbstract:The emergence of global order in complex systems with locally interacting components is most striking at criticality, where small changes in control parameters result in a sudden global reorganization. We study the Thermodynamic Efficiency of interactions in self-organizing systems, which quantifies the change in the system’s order per unit of work carried out on (or extracted from) the system. We analytically derive the Thermodynamic Efficiency of interactions for the case of quasi-static variations of control parameters in the exactly solvable Curie–Weiss (fully connected) Ising model, and demonstrate that this quantity diverges at the critical point of a second-order phase transition. This divergence is shown for quasi-static perturbations in both control parameters—the external field and the coupling strength. Our analysis formalizes an intuitive understanding of Thermodynamic Efficiency across diverse self-organizing dynamics in physical, biological, and social domains.
-
Thermodynamic Efficiency of interactions in self-organizing systems
arXiv: Statistical Mechanics, 2019Co-Authors: Ramil Nigmatullin, Mikhail ProkopenkoAbstract:The emergence of global order in complex systems with locally interacting components is most striking at criticality, where small changes in control parameters result in a sudden global re-organization. We introduce a measure of Thermodynamic Efficiency of interactions in self-organizing systems, which quantifies the change in the system's order per unit work carried out on (or extracted from) the system. We analytically derive the Thermodynamic Efficiency of interactions for the case of quasi-static variations of control parameters in the exactly solvable Curie-Weiss (fully connected) Ising model, and demonstrate that this quantity diverges at the critical point of a second order phase transition. This divergence is shown for quasi-static perturbations in both control parameters, the external field and the coupling strength. Our analysis formalizes an intuitive understanding of Thermodynamic Efficiency across diverse self-organizing dynamics in physical, biological and social domains.
-
Thermodynamic Efficiency of contagions a statistical mechanical analysis of the sis epidemic model
Interface Focus, 2018Co-Authors: Nathan Harding, Ramil Nigmatullin, Mikhail ProkopenkoAbstract:We present a novel approach to the study of epidemics on networks as Thermodynamic phenomena, quantifying the Thermodynamic Efficiency of contagions, considered as distributed computational processes. Modelling SIS dynamics on a contact network statistical-mechanically, we follow the maximum entropy (MaxEnt) principle to obtain steady-state distributions and derive, under certain assumptions, relevant Thermodynamic quantities both analytically and numerically. In particular, we obtain closed-form solutions for some cases, while interpreting key epidemic variables, such as the reproductive ratio of a SIS model, in a statistical mechanical setting. On the other hand, we consider configuration and free entropy, as well as the Fisher information, in the epidemiological context. This allowed us to identify criticality and distinct phases of epidemic processes. For each of the considered Thermodynamic quantities, we compare the analytical solutions informed by the MaxEnt principle with the numerical estimates for SIS epidemics simulated on Watts-Strogatz random graphs.
-
on critical dynamics and Thermodynamic Efficiency of urban transformations
Royal Society Open Science, 2018Co-Authors: Emanuele Crosato, Ramil Nigmatullin, Mikhail ProkopenkoAbstract:Urban transformations within large and growing metropolitan areas often generate critical dynamics affecting social interactions, transport connectivity and income flow distribution. We develop a s...
-
on critical dynamics and Thermodynamic Efficiency of urban transformations
Research Papers in Economics, 2018Co-Authors: Emanuele Crosato, Ramil Nigmatullin, Mikhail ProkopenkoAbstract:Urban transformations within large and growing metropolitan areas often generate critical dynamics affecting social interactions, transport connectivity and income flow distribution. We develop a statistical-mechanical model of urban transformations, exemplified for Greater Sydney, and derive a Thermodynamic description highlighting critical regimes. We consider urban dynamics at two time scales: fast dynamics for the distribution of population and income, modelled via the maximum entropy principle, and slower dynamics evolving the urban structure under spatially distributed competition. We identify phase transitions between dispersed and polycentric phases, induced by varying the social disposition---a factor balancing the suburbs' attractiveness---in contrast with the travel impedance. Using the Fisher information we identify critical thresholds and quantify the Thermodynamic cost of urban transformation, as the minimal work required to vary the underlying parameter. Finally, we introduce the notion of Thermodynamic Efficiency of urban transformation, as the ratio of the order gained during a change to the amount of required work, showing that this measure is maximised at criticality.
