The Experts below are selected from a list of 250935 Experts worldwide ranked by ideXlab platform
Mehmet F Orhan - One of the best experts on this subject based on the ideXlab platform.
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energy and exergy analyses of the fluidized bed of a copper chlorine cycle for nuclear based hydrogen Production via thermochemical water decomposition
Chemical Engineering Research & Design, 2009Co-Authors: Mehmet F Orhan, Ibrahim Dincer, Marc A. RosenAbstract:Abstract Nuclear-based hydrogen Production via thermochemical water decomposition using a copper–chlorine (Cu–Cl) cycle consists of a series of chemical reactions in which water is split into hydrogen and oxygen as the net result. This is accomplished through reactions involving intermediate copper and chlorine compounds, which are recycled. This cycle consists of three thermally driven reactions and one electrochemical reaction. The cycle involves five Steps: (1) HCl(g) Production using such equipment as a fluidized bed, (2) oxygen Production, (3) copper(Cu) Production, (4) drying, and (5) hydrogen Production. A chemical reaction takes place in each Step, except drying. In this study, the HCI(g) Production Step of the Cu–Cl cycle for hydrogen Production as well as its operational and environmental conditions are defined, and a comprehensive thermodynamic analysis is performed, incorporating energy and exergy and considering relevant chemical reactions. The performance of the fluidized bed is evaluated through energy and exergy efficiencies, and various parametric studies on energetic and exergetic aspects with variable reaction and reference-environment temperatures are carried out.
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the oxygen Production Step of a copper chlorine thermochemical water decomposition cycle for hydrogen Production energy and exergy analyses
Chemical Engineering Science, 2009Co-Authors: Mehmet F OrhanAbstract:Abstract In the copper–chlorine (Cu–Cl) thermochemical cycle water is decomposed into its constituents (oxygen and hydrogen) by a series of chemical reactions. The cycle involves five Steps in which three thermally driven chemical reactions and one electrochemical reaction take place. Oxygen is produced during one of the main chemical reactions. In the present study, the O 2 Production Step is described with its operational and environmental conditions, and energy and exergy analyses are performed. The cycle is assumed driven using nuclear energy. Various parametric studies are carried out on energetic and exergetic aspects of the Step, considering variable reaction and reference-environment temperatures. At a constant reference-environment temperature of 25 °C, the exergy destruction of the O 2 Production Step varies between 4500 and 23,000 kJ/kmol H 2 when the reaction temperature increases from 450 to 1000 °C. At a 500 °C reaction temperature and a 25 °C reference-environment temperature, the exergy destruction for this Step is found to be 5300 kJ/kmol H 2 . At a reaction temperature of 500 °C and a reference-environment temperature of 25 °C, the exergy efficiency of the Step is determined to be 96% and to decrease with increasing reaction temperature and/or reference-environment temperature.
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thermodynamic analysis of the copper Production Step in a copper chlorine cycle for hydrogen Production
Thermochimica Acta, 2008Co-Authors: Mehmet F OrhanAbstract:Abstract The hybrid copper–chlorine (Cu–Cl) thermo/electrochemical cycle for decomposing water into its constituents is a novel method for hydrogen Production. The process involves a series of closed-loop chemical reactions. The cycle is assumed driven in an environmentally benign manner using nuclear energy. The cycle involves five Steps of which three are thermally driven chemical reactions and one has an electrochemical reaction. In the present study, the electrochemical reaction, copper (Cu) Production Step, is described with its operational and environmental conditions, and analyzed thermodynamically. Various parametric studies are carried out on energetic and exergetic aspects of the Step, considering variable reaction and reference-environment temperatures. At a reaction temperature of 45 °C, the reaction heat of the Cu Production Step is 140,450 kJ/kmol H 2 . At a constant reaction temperature of 45 °C, the exergy destruction of the Step varies between 50 kJ/kmol H 2 and 7000 kJ/kmol H 2 when the reference-environment temperature increases from 0 °C to 30 °C. At a reaction temperature of 45 °C and a reference-environment temperature of 25 °C, the exergy efficiency of this Step is 99% and decreases with increasing reference-environment and/or reaction temperatures.
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energy and exergy assessments of the hydrogen Production Step of a copper chlorine thermochemical water splitting cycle driven by nuclear based heat
International Journal of Hydrogen Energy, 2008Co-Authors: Mehmet F OrhanAbstract:Abstract Water is split into hydrogen and oxygen as the net result of the copper–chlorine (Cu–Cl) thermochemical water decomposition cycle. The cycle involves five Steps: (1) HCl(g) Production using such equipment as a fluidized bed, (2) oxygen Production, (3) copper (Cu) Production, (4) drying, and (5) hydrogen Production. A chemical reaction takes place in each Step, except drying. In the present study the hydrogen Production Step of the Cu–Cl cycle is assessed thermodynamically using energy and exergy methods and considering relevant chemical reactions. Energy and exergy efficiencies of the H2 Production Step are evaluated and parametric studies are carried out on energetic and exergetic aspects considering variable reaction and reference-environment temperatures. At a reaction temperature of 450 °C, the reaction heat of the H2 Production Step is equal to −55,500 kJ/kmol H2 (exothermic reaction). At a constant reference-environment temperature of 25 °C, the exergy destruction of the H2 Production Step varies between 1000 kJ/kmol H2 and 7000 kJ/kmol H2 when the reaction temperature increases from 300 °C to 450 °C. The exergy destruction decreases with increasing reaction temperature. At a reaction temperature of 450 °C and a reference-environment temperature of 25 °C, the exergy efficiency of this Step is 99% and decreases with increasing reference-environment temperature and increases with increasing reaction temperature. The hydrogen Production process is assumed to be driven by nuclear-based heat, yielding an environmentally benign overall process.
Konstantinos Kakosimos - One of the best experts on this subject based on the ideXlab platform.
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solar hybrid photo thermochemical sulfur ammonia water splitting cycle photocatalytic hydrogen Production stage
International Journal of Hydrogen Energy, 2017Co-Authors: Ekaterini Ch Vagia, Nazim Muradov, A E Kalyva, Ali Traissi, Arun R. Srinivasa, Konstantinos KakosimosAbstract:Abstract One of the main limitations of existing solar thermochemical water-splitting cycles (WSC) are that they utilize only thermal component of the solar irradiation neglecting its photonic component. A new hybrid photo-thermochemical sulfur–ammonia (HySA) WSC developed at the Florida Solar Energy Center allows circumventing this shortcoming. In the HySA cycle, water splitting occurs by means of solar beam splitting which enables utilization of the quantum (UV–Vis) portion of the solar spectrum in the hydrogen Production stage and the thermal (IR) portion in the oxygen Production stage. Present work investigates the photocatalytic hydrogen Production Step using narrow band gap CdS and CdS ZnS composite photocatalysts, and ammonium sulfite as an electron donor. The choice of the electron donor was determined by the considerations of its regenerability in the thermal stages of the HySA cycle. This article examines the impact of photocatalyst and cocatalyst loading, temperature, and light intensity on hydrogen Production rates. Photocatalysts, cocatalysts and photoreaction products were analyzed by a number of materials characterization (XRD, SEM, TEM, EDS) and analytical (GC and IC) methods. The experimental data obtained provide guidance for the improved solar photoreactor design.
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hybrid photo thermal sulfur ammonia water splitting cycle thermodynamic analysis of the thermochemical Steps
International Journal of Hydrogen Energy, 2017Co-Authors: Nazim Muradov, A E Kalyva, Ali Traissi, Arun R. Srinivasa, Ch E Vagia, Athanasios G Konstandopoulos, Konstantinos KakosimosAbstract:Abstract Solar driven hybrid sulfur-ammonia water splitting cycle (HySA) integrates a solar-photocatalytic hydrogen, H 2 , Production Step (H 2 sub-cycle) with a high-temperature solar thermochemical oxygen, O 2 , evolution Step (O 2 sub-cycle), implementing efficient thermal energy storage as part of the cycle operation. Previous studies of the cycle omitted intermediate products, such as ammonium bisulfate, from the O 2 sub-cycle and, thus, neglected their potential impact on the cycle's chemistry. Also, there are discrepancies in reported literature for the thermodynamic properties of ammonium sulfate, (NH 4 ) 2 SO 4, and ammonium bisulfate, NH 4 HSO 4 . In this study, thermal analysis experiments were conducted in order to determine the phase transition temperatures and enthalpies, and the heat capacity temperature dependence of the ammonium sulfate, (NH 4 ) 2 SO 4, and ammonium bisulfate, NH 4 HSO 4 . Our experimentally determined values for these parameters agree well with the data reported in DIPPR Project 801 database. Moreover, an exploratory thermodynamic analyses was performed using AspenPlus © and FactSage © , that included all potential reaction products, in order to identify critical parameters for an optimum O 2 sub-cycle. A methodology is proposed and evaluated to mitigate AspenPlus © 's deficiency to handle solid phase changes. The thermodynamic analyses demonstrate that the NH 4 HSO 4 inclusion in the O 2 sub-cycle reduces the overall process energy requirements, and allows its use as an energy storage medium. Finally, we show that the use of molten salts, in combination with their interactions, significantly affects the efficiency and the operating conditions of the process, as well as the state of the mixtures.
A E Kalyva - One of the best experts on this subject based on the ideXlab platform.
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solar hybrid photo thermochemical sulfur ammonia water splitting cycle photocatalytic hydrogen Production stage
International Journal of Hydrogen Energy, 2017Co-Authors: Ekaterini Ch Vagia, Nazim Muradov, A E Kalyva, Ali Traissi, Arun R. Srinivasa, Konstantinos KakosimosAbstract:Abstract One of the main limitations of existing solar thermochemical water-splitting cycles (WSC) are that they utilize only thermal component of the solar irradiation neglecting its photonic component. A new hybrid photo-thermochemical sulfur–ammonia (HySA) WSC developed at the Florida Solar Energy Center allows circumventing this shortcoming. In the HySA cycle, water splitting occurs by means of solar beam splitting which enables utilization of the quantum (UV–Vis) portion of the solar spectrum in the hydrogen Production stage and the thermal (IR) portion in the oxygen Production stage. Present work investigates the photocatalytic hydrogen Production Step using narrow band gap CdS and CdS ZnS composite photocatalysts, and ammonium sulfite as an electron donor. The choice of the electron donor was determined by the considerations of its regenerability in the thermal stages of the HySA cycle. This article examines the impact of photocatalyst and cocatalyst loading, temperature, and light intensity on hydrogen Production rates. Photocatalysts, cocatalysts and photoreaction products were analyzed by a number of materials characterization (XRD, SEM, TEM, EDS) and analytical (GC and IC) methods. The experimental data obtained provide guidance for the improved solar photoreactor design.
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hybrid photo thermal sulfur ammonia water splitting cycle thermodynamic analysis of the thermochemical Steps
International Journal of Hydrogen Energy, 2017Co-Authors: Nazim Muradov, A E Kalyva, Ali Traissi, Arun R. Srinivasa, Ch E Vagia, Athanasios G Konstandopoulos, Konstantinos KakosimosAbstract:Abstract Solar driven hybrid sulfur-ammonia water splitting cycle (HySA) integrates a solar-photocatalytic hydrogen, H 2 , Production Step (H 2 sub-cycle) with a high-temperature solar thermochemical oxygen, O 2 , evolution Step (O 2 sub-cycle), implementing efficient thermal energy storage as part of the cycle operation. Previous studies of the cycle omitted intermediate products, such as ammonium bisulfate, from the O 2 sub-cycle and, thus, neglected their potential impact on the cycle's chemistry. Also, there are discrepancies in reported literature for the thermodynamic properties of ammonium sulfate, (NH 4 ) 2 SO 4, and ammonium bisulfate, NH 4 HSO 4 . In this study, thermal analysis experiments were conducted in order to determine the phase transition temperatures and enthalpies, and the heat capacity temperature dependence of the ammonium sulfate, (NH 4 ) 2 SO 4, and ammonium bisulfate, NH 4 HSO 4 . Our experimentally determined values for these parameters agree well with the data reported in DIPPR Project 801 database. Moreover, an exploratory thermodynamic analyses was performed using AspenPlus © and FactSage © , that included all potential reaction products, in order to identify critical parameters for an optimum O 2 sub-cycle. A methodology is proposed and evaluated to mitigate AspenPlus © 's deficiency to handle solid phase changes. The thermodynamic analyses demonstrate that the NH 4 HSO 4 inclusion in the O 2 sub-cycle reduces the overall process energy requirements, and allows its use as an energy storage medium. Finally, we show that the use of molten salts, in combination with their interactions, significantly affects the efficiency and the operating conditions of the process, as well as the state of the mixtures.
Marc A. Rosen - One of the best experts on this subject based on the ideXlab platform.
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thermodynamic viability of a new three Step high temperature cu cl cycle for hydrogen Production
International Journal of Hydrogen Energy, 2018Co-Authors: Farrukh Khalid, Ibrahim Dincer, Marc A. RosenAbstract:Abstract A new three Step high temperature Cu-Cl thermochemical cycle for hydrogen Production is presented. The performance of the proposed cycle is investigated through energy and exergy approaches. Furthermore, the effects of various parameters, such as the temperatures of the Steps of the cycle and power plant efficiency, on various energy and exergy efficiencies are assessed with parametric studies. The results show that the exergy and energy efficiencies of the proposed cycle are 68.3% and 32.0%, respectively. In addition, the exergy analysis results reveal that the hydrogen Production Step has the maximum specific exergy destruction with a value of 150.9 kJ/mol. The results suggest that proposed cycle may provide enhanced options for high temperature thermochemical cycles by improving thermal management without causing a sudden temperature jump/fall between the hydrogen Production Step and other Steps.
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energy and exergy analyses of the fluidized bed of a copper chlorine cycle for nuclear based hydrogen Production via thermochemical water decomposition
Chemical Engineering Research & Design, 2009Co-Authors: Mehmet F Orhan, Ibrahim Dincer, Marc A. RosenAbstract:Abstract Nuclear-based hydrogen Production via thermochemical water decomposition using a copper–chlorine (Cu–Cl) cycle consists of a series of chemical reactions in which water is split into hydrogen and oxygen as the net result. This is accomplished through reactions involving intermediate copper and chlorine compounds, which are recycled. This cycle consists of three thermally driven reactions and one electrochemical reaction. The cycle involves five Steps: (1) HCl(g) Production using such equipment as a fluidized bed, (2) oxygen Production, (3) copper(Cu) Production, (4) drying, and (5) hydrogen Production. A chemical reaction takes place in each Step, except drying. In this study, the HCI(g) Production Step of the Cu–Cl cycle for hydrogen Production as well as its operational and environmental conditions are defined, and a comprehensive thermodynamic analysis is performed, incorporating energy and exergy and considering relevant chemical reactions. The performance of the fluidized bed is evaluated through energy and exergy efficiencies, and various parametric studies on energetic and exergetic aspects with variable reaction and reference-environment temperatures are carried out.
Nazim Muradov - One of the best experts on this subject based on the ideXlab platform.
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solar hybrid photo thermochemical sulfur ammonia water splitting cycle photocatalytic hydrogen Production stage
International Journal of Hydrogen Energy, 2017Co-Authors: Ekaterini Ch Vagia, Nazim Muradov, A E Kalyva, Ali Traissi, Arun R. Srinivasa, Konstantinos KakosimosAbstract:Abstract One of the main limitations of existing solar thermochemical water-splitting cycles (WSC) are that they utilize only thermal component of the solar irradiation neglecting its photonic component. A new hybrid photo-thermochemical sulfur–ammonia (HySA) WSC developed at the Florida Solar Energy Center allows circumventing this shortcoming. In the HySA cycle, water splitting occurs by means of solar beam splitting which enables utilization of the quantum (UV–Vis) portion of the solar spectrum in the hydrogen Production stage and the thermal (IR) portion in the oxygen Production stage. Present work investigates the photocatalytic hydrogen Production Step using narrow band gap CdS and CdS ZnS composite photocatalysts, and ammonium sulfite as an electron donor. The choice of the electron donor was determined by the considerations of its regenerability in the thermal stages of the HySA cycle. This article examines the impact of photocatalyst and cocatalyst loading, temperature, and light intensity on hydrogen Production rates. Photocatalysts, cocatalysts and photoreaction products were analyzed by a number of materials characterization (XRD, SEM, TEM, EDS) and analytical (GC and IC) methods. The experimental data obtained provide guidance for the improved solar photoreactor design.
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hybrid photo thermal sulfur ammonia water splitting cycle thermodynamic analysis of the thermochemical Steps
International Journal of Hydrogen Energy, 2017Co-Authors: Nazim Muradov, A E Kalyva, Ali Traissi, Arun R. Srinivasa, Ch E Vagia, Athanasios G Konstandopoulos, Konstantinos KakosimosAbstract:Abstract Solar driven hybrid sulfur-ammonia water splitting cycle (HySA) integrates a solar-photocatalytic hydrogen, H 2 , Production Step (H 2 sub-cycle) with a high-temperature solar thermochemical oxygen, O 2 , evolution Step (O 2 sub-cycle), implementing efficient thermal energy storage as part of the cycle operation. Previous studies of the cycle omitted intermediate products, such as ammonium bisulfate, from the O 2 sub-cycle and, thus, neglected their potential impact on the cycle's chemistry. Also, there are discrepancies in reported literature for the thermodynamic properties of ammonium sulfate, (NH 4 ) 2 SO 4, and ammonium bisulfate, NH 4 HSO 4 . In this study, thermal analysis experiments were conducted in order to determine the phase transition temperatures and enthalpies, and the heat capacity temperature dependence of the ammonium sulfate, (NH 4 ) 2 SO 4, and ammonium bisulfate, NH 4 HSO 4 . Our experimentally determined values for these parameters agree well with the data reported in DIPPR Project 801 database. Moreover, an exploratory thermodynamic analyses was performed using AspenPlus © and FactSage © , that included all potential reaction products, in order to identify critical parameters for an optimum O 2 sub-cycle. A methodology is proposed and evaluated to mitigate AspenPlus © 's deficiency to handle solid phase changes. The thermodynamic analyses demonstrate that the NH 4 HSO 4 inclusion in the O 2 sub-cycle reduces the overall process energy requirements, and allows its use as an energy storage medium. Finally, we show that the use of molten salts, in combination with their interactions, significantly affects the efficiency and the operating conditions of the process, as well as the state of the mixtures.
