The Experts below are selected from a list of 231 Experts worldwide ranked by ideXlab platform
Takafumi Hirata - One of the best experts on this subject based on the ideXlab platform.
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Heavy element stable isotope ratios : analytical approaches and applications
Analytical and Bioanalytical Chemistry, 2013Co-Authors: Masaharu Tanimizu, Yoshiki Sohrin, Takafumi HirataAbstract:Continuous developments in inorganic mass spectrometry techniques, including a combination of an inductively coupled plasma ion source and a magnetic sector-based mass spectrometer equipped with a multiple-Collector Array, have revolutionized the precision of isotope ratio measurements, and applications of inorganic mass spectrometry for biochemistry, geochemistry, and marine chemistry are beginning to appear on the horizon. Series of pioneering studies have revealed that natural stable isotope fractionations of many elements heavier than S (e.g., Fe, Cu, Zn, Sr, Ce, Nd, Mo, Cd, W, Tl, and U) are common on Earth, and it had been widely recognized that most physicochemical reactions or biochemical processes induce mass-dependent isotope fractionation. The variations in isotope ratios of the heavy elements can provide new insights into past and present biochemical and geochemical processes. To achieve this, the analytical community is actively solving problems such as spectral interference, mass discrimination drift, chemical separation and purification, and reduction of the contamination of analytes. This article describes data calibration and standardization protocols to allow interlaboratory comparisons or to maintain traceability of data, and basic principles of isotope fractionation in nature, together with high-selectivity and high-yield chemical separation and purification techniques for stable isotope studies. Figure Isotope ratios of the elements can vary through almost all the chemical and biochemical reactions in nature
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Heavy element stable isotope ratios: analytical approaches and applications.
Analytical and bioanalytical chemistry, 2013Co-Authors: Masaharu Tanimizu, Yoshiki Sohrin, Takafumi HirataAbstract:Continuous developments in inorganic mass spectrometry techniques, including a combination of an inductively coupled plasma ion source and a magnetic sector-based mass spectrometer equipped with a multiple-Collector Array, have revolutionized the precision of isotope ratio measurements, and applications of inorganic mass spectrometry for biochemistry, geochemistry, and marine chemistry are beginning to appear on the horizon. Series of pioneering studies have revealed that natural stable isotope fractionations of many elements heavier than S (e.g., Fe, Cu, Zn, Sr, Ce, Nd, Mo, Cd, W, Tl, and U) are common on Earth, and it had been widely recognized that most physicochemical reactions or biochemical processes induce mass-dependent isotope fractionation. The variations in isotope ratios of the heavy elements can provide new insights into past and present biochemical and geochemical processes. To achieve this, the analytical community is actively solving problems such as spectral interference, mass discrimination drift, chemical separation and purification, and reduction of the contamination of analytes. This article describes data calibration and standardization protocols to allow interlaboratory comparisons or to maintain traceability of data, and basic principles of isotope fractionation in nature, together with high-selectivity and high-yield chemical separation and purification techniques for stable isotope studies.
Masaharu Tanimizu - One of the best experts on this subject based on the ideXlab platform.
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Heavy element stable isotope ratios : analytical approaches and applications
Analytical and Bioanalytical Chemistry, 2013Co-Authors: Masaharu Tanimizu, Yoshiki Sohrin, Takafumi HirataAbstract:Continuous developments in inorganic mass spectrometry techniques, including a combination of an inductively coupled plasma ion source and a magnetic sector-based mass spectrometer equipped with a multiple-Collector Array, have revolutionized the precision of isotope ratio measurements, and applications of inorganic mass spectrometry for biochemistry, geochemistry, and marine chemistry are beginning to appear on the horizon. Series of pioneering studies have revealed that natural stable isotope fractionations of many elements heavier than S (e.g., Fe, Cu, Zn, Sr, Ce, Nd, Mo, Cd, W, Tl, and U) are common on Earth, and it had been widely recognized that most physicochemical reactions or biochemical processes induce mass-dependent isotope fractionation. The variations in isotope ratios of the heavy elements can provide new insights into past and present biochemical and geochemical processes. To achieve this, the analytical community is actively solving problems such as spectral interference, mass discrimination drift, chemical separation and purification, and reduction of the contamination of analytes. This article describes data calibration and standardization protocols to allow interlaboratory comparisons or to maintain traceability of data, and basic principles of isotope fractionation in nature, together with high-selectivity and high-yield chemical separation and purification techniques for stable isotope studies. Figure Isotope ratios of the elements can vary through almost all the chemical and biochemical reactions in nature
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Heavy element stable isotope ratios: analytical approaches and applications.
Analytical and bioanalytical chemistry, 2013Co-Authors: Masaharu Tanimizu, Yoshiki Sohrin, Takafumi HirataAbstract:Continuous developments in inorganic mass spectrometry techniques, including a combination of an inductively coupled plasma ion source and a magnetic sector-based mass spectrometer equipped with a multiple-Collector Array, have revolutionized the precision of isotope ratio measurements, and applications of inorganic mass spectrometry for biochemistry, geochemistry, and marine chemistry are beginning to appear on the horizon. Series of pioneering studies have revealed that natural stable isotope fractionations of many elements heavier than S (e.g., Fe, Cu, Zn, Sr, Ce, Nd, Mo, Cd, W, Tl, and U) are common on Earth, and it had been widely recognized that most physicochemical reactions or biochemical processes induce mass-dependent isotope fractionation. The variations in isotope ratios of the heavy elements can provide new insights into past and present biochemical and geochemical processes. To achieve this, the analytical community is actively solving problems such as spectral interference, mass discrimination drift, chemical separation and purification, and reduction of the contamination of analytes. This article describes data calibration and standardization protocols to allow interlaboratory comparisons or to maintain traceability of data, and basic principles of isotope fractionation in nature, together with high-selectivity and high-yield chemical separation and purification techniques for stable isotope studies.
Roland Winston - One of the best experts on this subject based on the ideXlab platform.
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Performance of the Sacramento demonstration ICPC Collector and double effect chiller
Solar Energy, 2020Co-Authors: William S. Duff, Roland Winston, Joseph J. O'gallagher, James Bergquam, Thomas HenkelAbstract:Abstract In 1998 two new technologies were demonstrated for the first time in a commercial building: (1) a new integrated CPC reflector evacuated solar Collector (ICPC) and (2) the solar operation of a double effect absorption (2E) chiller. The 106.5 m2 ICPC Collector Array consisted of 336 evacuated tubes. A commercial 2E gas-fired absorption chiller was modified to operate with 150 °C hot water from the solar Collector Array. Daily collection efficiencies of nearly 50% and instantaneous collection efficiencies of about 60% were achieved throughout the first two years of operation. Daily chiller COPs of about 1.1 were also achieved.
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Solar thermal drum drying performance of prune and tomato pomaces
Food and Bioproducts Processing, 2017Co-Authors: Rebecca R. Milczarek, Jonathan J. Ferry, Fatima S. Alleyne, Carl W. Olsen, Donald A. Olson, Roland WinstonAbstract:Fruit and vegetable pomaces are co-products of the food processing industry; they are underutilized in part because their high water activity (aw) renders them unstable. Drum drying is one method that can dry/stabilize pomaces, but current drum drying methods utilize conventional, high-environmental-impact heating mechanisms. In this work, a small-scale double drum dryer (20 cm length × 15 cm diameter) was interfaced with a 98.3 m2External Compound Parabolic Concentrator (XCPC) [solar thermal Collector] Array designed to produce up to approximately 40 kW of heating power. The conditions for drying prune and tomato pomaces were optimized on this system via a split-plot design. The design had 4 variables: added water, added maltodextrin carrier, dwell time, and drum surface temperature. Moisture content, aw, and color of the dried pomaces were assessed to determine the effectiveness of the drying. Both pomaces were rendered shelf-stable (aw< 0.6) for all tested conditions. However, prune pomace exhibited a narrower range of awvalues than did tomato pomace. Conditions for adequate drying with minimal color change (and thus expected minimal nutrition loss) were established. This work demonstrates the potential for solar thermal energy to provide the heat for drum drying fruit and vegetable pomaces.
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Performance of a 23KW solar thermal cooling system employing a double effect absorption chiller and thermodynamically efficient non-tracking concentrators
Energy Procedia, 2014Co-Authors: Roland Winston, Lun Jiang, Bennett WidyolarAbstract:A solar thermal cooling system using novel non-tracking External Compound Parabolic Concentrators (XCPC) has been built and operated for two cooling seasons (summers of 2011 and 2012). Its performance in providing power for space cooling has been analyzed. This solar cooling system is comprised of 53.3 m2of XCPC trough Collectors which are used to power a 23 kW double effect (LiBr) absorption chiller. This is the first system that combines both XCPC and absorption chilling technologies. Performance of the system was measured in both sunny and cloudy conditions. The Collector system maintained operating temperatures between 160-200 °C. When operated in this temperature range, the XCPC Collector Array collected solar energy with an average daily efficiency of 36.7% and reached instantaneous efficiencies up to 40%. The thermal COP of the system (including thermal losses and COP of absorption chiller) averaged at 0.99 and the daily solar COP of the entire system averaged 0.363. It was found that these Collectors are well suited at providing thermal power to drive absorption cooling systems and that both the coinciding of available thermal power with cooling demand and the simplicity of the XCPC Collectors compared to other solar thermal Collectors makes them a highly attractive candidate for cooling projects. XCPC technology has numerous potential applications and is currently being commercialized in the U.S. and India.
Christos N. Markides - One of the best experts on this subject based on the ideXlab platform.
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Optimisation of a high-efficiency solar-driven organic Rankine cycle for applications in the built environment
Applied Energy, 2018Co-Authors: A. Ramos, Maria Anna Chatzopoulou, James Freeman, Christos N. MarkidesAbstract:Abstract Energy security, pollution and sustainability are major challenges presently facing the international community, in response to which increasing quantities of renewable energy are to be generated in the urban environment. Consequently, recent years have seen a strong increase in the uptake of solar technologies in the building sector. In this work, the potential of a solar combined heat and power (CHP) system based on an organic Rankine cycle (ORC) engine is investigated in a domestic setting. Unlike previous studies that focus on the optimisation of the ORC subsystem, this study performs a complete system optimisation considering both the design parameters of the solar Collector Array and the ORC engine simultaneously. Firstly, we present thermodynamic models of different Collectors, including flat-plate and evacuated-tube designs, coupled to a non-recuperative sub-critical ORC architecture that delivers power and hot water by using thermal energy rejected from the engine. Optimisation of the complete system is first conducted, aimed at identifying operating conditions for which the power output is maximised. Then, hourly dynamic simulations of the optimised system configurations are performed to complete the system sizing. Results are presented of: (i) dynamic 3-D simulations of the solar Collectors together with a thermal energy storage tank, and (ii) of an optimisation analysis to identify the most suitable working fluids for the ORC engine, in which the configuration and operational constraints of the Collector Array are considered. The best performing working fluids (R245fa and R1233zd) are then chosen for a whole-system annual simulation in a southern European climate. The system configuration combining an evacuated-tube Collector Array and an ORC engine is found to be best-suited for electricity prioritisation, delivering an electrical output of 3,605 kWh/year from a 60 m2 Collector Array. In addition, the system supplies 13,175 kWh/year in the form of domestic hot water, which is equivalent to more than 6 times the average annual household demand. A brief cost analysis and comparison with photovoltaic (PV) systems is also performed, where despite the lower PV investment cost per kWel, the levelised energy costs of the different systems are found to be similar if the economic value of the thermal output is taken into account. Finally, a discussion of the modelled solar-CHP systems results shows how these could be used for real applications and extended to other locations.
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a small scale solar organic rankine cycle combined heat and power system with integrated thermal energy storage
Applied Thermal Engineering, 2017Co-Authors: James Freeman, I Guarracino, Soteris A Kalogirou, Christos N. MarkidesAbstract:Abstract In this paper, we examine integrated thermal energy storage (TES) solutions for a domestic-scale solar combined heat and power (S-CHP) system based on an organic Rankine cycle (ORC) engine and low-cost non-concentrating solar-thermal Collectors. TES is a critical element and distinct advantage of solar-thermal systems. It can allow, depending on how it is implemented, improved matching to the end-user demands, improved load factors, higher average efficiencies and overall performance, as well as reduced component and system sizes and costs, especially in climates with high solar-irradiance variability. The operating temperature range of the TES solution must be compatible with the solar-Collector Array and with the ORC engine operation in order to maximise the overall performance of the system. Various combinations of phase change materials (PCMs) and solar Collectors are compared and the S-CHP system’s performance is simulated for selected months in the contrasting climates of Cyprus and the UK. The most important performance indicator of the ORC engine, i.e., net-power output, and the required TES volume are compared and discussed. The PCM-TES solutions that enable the best summer performance from an ORC engine sized for a nominal ∼1-kWe output in combination with a 15-m2 solar Collector Array result in diurnal volume requirements as low as ∼100 L in Cyprus and 400–500 L in the UK. However, the required TES volume is strongly influenced by the choice of operational strategy for the system in matching the domestic load profiles. In a full-storage strategy in which electrical energy generation from the ORC engine is offset to match the week-day evening peak in demand, it is found that a ∼20% higher total daily electrical output per unit storage volume can be achieved with a PCM compared to water as a sensible storage medium. The isothermal operation of the PCMs during phase-change allows for smaller diurnal storage temperature swings and higher energy conversion efficiencies from the solar Collector Array. These results are useful in informing the development of small-scale solar-thermal heat and power systems and of suitable integrated TES solutions for such applications.
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Thermo-economic Assessment of an Externally Fired Hybrid CSP/biomass Gas Turbine and Organic Rankine Combined Cycle
Energy Procedia, 2017Co-Authors: Antonio M. Pantaleo, Christos N. Markides, Sergio Mario Camporeale, Adio Miliozzi, V. Russo, Giacomo Scarascia Mugnozza, Nilay ShahAbstract:Abstract This paper focuses on the thermo-economic analysis of a hybrid solar-biomass CHP combined cycle composed by a 1.3-MW externally fired gas-turbine (EFGT) and a bottoming organic Rankine cycle (ORC) plant. The primary thermal energy input is provided by a hybrid concentrating solar power (CSP) Collector-Array coupled to a biomass boiler. The CSP Collector-Array is based on parabolic-trough concentrators (PTCs) with molten salts as the heat transfer fluid (HTF) upstream of a fluidized-bed furnace for direct biomass combustion. Thermal-energy storage (TES) with two molten-salt tanks (one cold and one hot) is considered, as a means to reducing the variations in the plant's operating conditions and increasing the plant's capacity factor. On the basis of the results of the thermodynamic simulations, upfront and operational costs assessments, and considering an Italian energy policy scenario, the global energy conversion efficiency and investment profitability are estimated for 2 different sizes of CSP Arrays and biomass furnaces. The results indicate the low economic profitability of CSP in comparison to only biomass CHP, because of the high investment costs, which are not compensated by higher electricity sales revenues.
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an assessment of solar powered organic rankine cycle systems for combined heating and power in uk domestic applications
Applied Energy, 2015Co-Authors: James Freeman, Klaus Hellgardt, Christos N. MarkidesAbstract:Performance calculations are presented for a small-scale combined solar heat and power (CSHP) system based on an Organic Rankine Cycle (ORC), in order to investigate the potential of this technology for the combined provision of heating and power for domestic use in the UK. The system consists of a solar Collector Array of total area equivalent to that available on the roof of a typical UK home, an ORC engine featuring a generalised positive-displacement expander and a water-cooled condenser, and a hot water storage cylinder. Preheated water from the condenser is sent to the domestic hot water cylinder, which can also receive an indirect heating contribution from the solar Collector. Annual simulations of the system are performed. The electrical power output from concentrating parabolic-trough (PTC) and non-concentrating evacuated-tube (ETC) Collectors of the same total Array area are compared. A parametric analysis and a life-cycle cost analysis are also performed, and the annual performance of the system is evaluated according to the total electrical power output and cost per unit generating capacity. A best-case average electrical power output of 89W (total of 776kWh/year) plus a hot water provision capacity equivalent to ∼80% of the total demand are demonstrated, for a whole system capital cost of £2700–£3900. Tracking PTCs are found to be very similar in performance to non-tracking ETCs with an average power output of 89W (776kWh/year) vs. 80W (701kWh/year).
Yoshiki Sohrin - One of the best experts on this subject based on the ideXlab platform.
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Heavy element stable isotope ratios : analytical approaches and applications
Analytical and Bioanalytical Chemistry, 2013Co-Authors: Masaharu Tanimizu, Yoshiki Sohrin, Takafumi HirataAbstract:Continuous developments in inorganic mass spectrometry techniques, including a combination of an inductively coupled plasma ion source and a magnetic sector-based mass spectrometer equipped with a multiple-Collector Array, have revolutionized the precision of isotope ratio measurements, and applications of inorganic mass spectrometry for biochemistry, geochemistry, and marine chemistry are beginning to appear on the horizon. Series of pioneering studies have revealed that natural stable isotope fractionations of many elements heavier than S (e.g., Fe, Cu, Zn, Sr, Ce, Nd, Mo, Cd, W, Tl, and U) are common on Earth, and it had been widely recognized that most physicochemical reactions or biochemical processes induce mass-dependent isotope fractionation. The variations in isotope ratios of the heavy elements can provide new insights into past and present biochemical and geochemical processes. To achieve this, the analytical community is actively solving problems such as spectral interference, mass discrimination drift, chemical separation and purification, and reduction of the contamination of analytes. This article describes data calibration and standardization protocols to allow interlaboratory comparisons or to maintain traceability of data, and basic principles of isotope fractionation in nature, together with high-selectivity and high-yield chemical separation and purification techniques for stable isotope studies. Figure Isotope ratios of the elements can vary through almost all the chemical and biochemical reactions in nature
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Heavy element stable isotope ratios: analytical approaches and applications.
Analytical and bioanalytical chemistry, 2013Co-Authors: Masaharu Tanimizu, Yoshiki Sohrin, Takafumi HirataAbstract:Continuous developments in inorganic mass spectrometry techniques, including a combination of an inductively coupled plasma ion source and a magnetic sector-based mass spectrometer equipped with a multiple-Collector Array, have revolutionized the precision of isotope ratio measurements, and applications of inorganic mass spectrometry for biochemistry, geochemistry, and marine chemistry are beginning to appear on the horizon. Series of pioneering studies have revealed that natural stable isotope fractionations of many elements heavier than S (e.g., Fe, Cu, Zn, Sr, Ce, Nd, Mo, Cd, W, Tl, and U) are common on Earth, and it had been widely recognized that most physicochemical reactions or biochemical processes induce mass-dependent isotope fractionation. The variations in isotope ratios of the heavy elements can provide new insights into past and present biochemical and geochemical processes. To achieve this, the analytical community is actively solving problems such as spectral interference, mass discrimination drift, chemical separation and purification, and reduction of the contamination of analytes. This article describes data calibration and standardization protocols to allow interlaboratory comparisons or to maintain traceability of data, and basic principles of isotope fractionation in nature, together with high-selectivity and high-yield chemical separation and purification techniques for stable isotope studies.