The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
Kazimierz Strzalka - One of the best experts on this subject based on the ideXlab platform.
-
low light induced violaxanthin de epoxidation in shortly preheated leaves uncoupling from δph dependent nonphotochemical quenching
Photochemistry and Photobiology, 2010Co-Authors: Petr Ilík, Martina Špundová, Eva Kotabova, Ondřej Novak, Radek Kaňa, Kazimierz StrzalkaAbstract:Plants protect themselves against excessive light by the induction of Delta pH-dependent nonphotochemical quenching (qE) that is associated with de-epoxidation of violaxanthin (V) to zeaxanthin (Z) in thylakoid membranes. In this work, we report that low light (12 micromol photons m(-2) s(-1)) is sufficient for a marked stimulation of the V to Z conversion in shortly preheated wheat leaves (5 min, 40 degrees C), but without a substantial increase in qE. Re-irradiation of these leaves with high light led to a rapid induction of nonphotochemical quenching, implying a potential photoprotective role of low-light-induced Z in preheated leaves. On the contrary to low light conditions, preheated leaves exposed to high light behaved similar to nonheated leaves with respect to the V to Z conversion and qE induction. The obtained results indicate that low-light-induced lumen acidification in preheated leaves is high enough to activate V de-epoxidation, but not sufficiently high to induce the formation of quenching centers.
Gang Xu - One of the best experts on this subject based on the ideXlab platform.
-
a supercritical co2 brayton cycle with a bleeding anabranch used in coal fired power plants
Energy, 2018Co-Authors: Guoqiang Zhang, Gang Xu, Y P Li, Yongping YangAbstract:Abstract This study investigates a novel supercritical carbon dioxide Brayton cycle with a bleeding anabranch used in coal-fired power plants. For the proper utilization of the medium-low temperature heat in the boiler, the coupling between the air-Preheater and the cycle is concentrated. After analyzing the distribution of heat duty in the boiler, the flow diagram of the Brayton cycle is design. Subsequently, the influences of maximal temperature/pressure, pinch temperature difference, component pressure drop, and preheated air temperature on the cycle efficiency are studied. Results show that the proposed cycle coupled with a coal-fired power plant can achieve 52.33% gross cycle efficiency and 49.5% net low heat value efficiency with 296 bar/650 °C. A further increment of 1% pt. in gross cycle efficiency can be achieved with the decrement of 5 K pinch temperature difference or 0.7 bar pressure loss in the recuperators. The simulation indicates that an increment of 2.14% pt. in gross cycle efficiency can be further achieved with 370 bar/700 °C. Besides, the parameter of the bleeding anabranch do not affect the cycle performance. In conclusion, this study proposes a promising novel supercritical carbon dioxide cycle coupled with coal-fired power plants.
-
a new conceptual cold end design of boilers for coal fired power plants with waste heat recovery
Energy Conversion and Management, 2015Co-Authors: Yongping Yang, Gang Xu, Cheng Xu, Yaxiong Fang, Dongke ZhangAbstract:Abstract After conducting an in-depth analysis of the conventional boiler cold-end design for waste heat recovery, this work proposed a new conceptual boiler cold-end design integrated with the steam cycle in a 1000 MW CFPP, in which the preheating of air was divided into high-temperature air Preheater (HTAP), main air Preheater (MAP) and low-temperature air Preheater (LTAP). The HTAP and an economizer were installed in separate flue ducts, and the low temperature economizer (LTE) was situated between the MAP and the LTAP in the main flue duct to heat the condensed water. In the proposed boiler cold-end design, the flue gas waste heat was not only used to heat condensed water, but also to further preheat the combustion air. The air temperature at the air-Preheater outlet increases and part of the steam bleeds with high exergy can be saved, resulting in greater energy-savings and better economics. Results showed that, for a typical 1000 MW CFPP in China, using the proposed boiler cold-end design for waste heat recovery could produce 13.3 MW e additional net power output with a heat rate reduction of approximately 112.0 kJ/kW h and could yield a net benefit of up to $85.8 M per year, which is much greater than those of the conventional cases. Exergy destruction is also reduced from 49.9 MW th in the conventional boiler cold-end design to 39.6 MW th in the proposed design.
-
a novel flue gas waste heat recovery system for coal fired ultra supercritical power plants
Applied Thermal Engineering, 2014Co-Authors: Gang Xu, Cheng Xu, Yongping Yang, Yaxiong Fang, Yuanyuan Li, Xiaona SongAbstract:Abstract Recovering flue gas waste heat is important in improving power plant efficiency. The most widely method is installing a low-temperature economizer (LTE) after the electrostatic precipitator (ESP) to heat the condensed water, thereby saving the extraction steam from the steam turbine and achieving extra work. The inlet flue gas temperature of the LTE is relatively low, so it can only heat condensed water from low-grade regenerative heaters, resulting in comparatively minor energy savings. After conducting an in-depth analysis of the conventional waste heat recovery system (WHRS), this paper proposes a novel WHRS, in which the air Preheater is divided into high-temperature (HT) and low-temperature (LT) air Preheaters, and the LTE can be situated between the ESP and the LT air Preheater. Through system integration, higher-grade extraction steam can be saved, resulting in greater economic benefits. Results show that the net additional power output can reach 9.00 MWe and using the proposed WHRS can yield net benefits up to USD 2.60 million per year, which is much greater than those of conventional WHRS. Exergy destruction is also reduced from 34.1 MWth in the conventional WHRS to 28.5 MWth in the proposed WHRS.
Petr Ilík - One of the best experts on this subject based on the ideXlab platform.
-
low light induced violaxanthin de epoxidation in shortly preheated leaves uncoupling from δph dependent nonphotochemical quenching
Photochemistry and Photobiology, 2010Co-Authors: Petr Ilík, Martina Špundová, Eva Kotabova, Ondřej Novak, Radek Kaňa, Kazimierz StrzalkaAbstract:Plants protect themselves against excessive light by the induction of Delta pH-dependent nonphotochemical quenching (qE) that is associated with de-epoxidation of violaxanthin (V) to zeaxanthin (Z) in thylakoid membranes. In this work, we report that low light (12 micromol photons m(-2) s(-1)) is sufficient for a marked stimulation of the V to Z conversion in shortly preheated wheat leaves (5 min, 40 degrees C), but without a substantial increase in qE. Re-irradiation of these leaves with high light led to a rapid induction of nonphotochemical quenching, implying a potential photoprotective role of low-light-induced Z in preheated leaves. On the contrary to low light conditions, preheated leaves exposed to high light behaved similar to nonheated leaves with respect to the V to Z conversion and qE induction. The obtained results indicate that low-light-induced lumen acidification in preheated leaves is high enough to activate V de-epoxidation, but not sufficiently high to induce the formation of quenching centers.
-
Low‐light‐induced Violaxanthin De‐epoxidation in Shortly Preheated Leaves: Uncoupling from ΔpH‐dependent Nonphotochemical Quenching
Photochemistry and Photobiology, 2010Co-Authors: Petr Ilík, Martina Špundová, Eva Kotabova, Ondřej Novak, Radek Kaňa, Kazimierz StrzałkaAbstract:Plants protect themselves against excessive light by the induction of Delta pH-dependent nonphotochemical quenching (qE) that is associated with de-epoxidation of violaxanthin (V) to zeaxanthin (Z) in thylakoid membranes. In this work, we report that low light (12 micromol photons m(-2) s(-1)) is sufficient for a marked stimulation of the V to Z conversion in shortly preheated wheat leaves (5 min, 40 degrees C), but without a substantial increase in qE. Re-irradiation of these leaves with high light led to a rapid induction of nonphotochemical quenching, implying a potential photoprotective role of low-light-induced Z in preheated leaves. On the contrary to low light conditions, preheated leaves exposed to high light behaved similar to nonheated leaves with respect to the V to Z conversion and qE induction. The obtained results indicate that low-light-induced lumen acidification in preheated leaves is high enough to activate V de-epoxidation, but not sufficiently high to induce the formation of quenching centers.
Ebrahim Hajidavalloo - One of the best experts on this subject based on the ideXlab platform.
-
three dimensional simulation of rotary air Preheater in steam power plant
Applied Thermal Engineering, 2014Co-Authors: Armin Heidarikaydan, Ebrahim HajidavallooAbstract:In this study, thermal behavior of a full-scale rotary air Preheater is investigated using three-dimensional approach and treating Preheater matrix as a porous media. Mass, momentum and energy equations are solved using moving reference frame (MRF) to incorporate the effect of rotational speed of the matrix. Temperature distributions of the matrix at different conditions have been presented and the effect of essential parameters such as rotational speed of the matrix, fluid mass flow, matrix material and temperature of inlet air on the performance of Preheater have been discussed. Numerical results which are confirmed by experimental data show the significant effect of rotational speed, separator plate, fluid flow rate on the performance and temperature distribution of Preheater. Increasing the rotational speed of the air heater increases the efficiency up to certain limit, after which it does not significantly change. It was also found that the effect of material change on the efficiency is very limited.
Eva Kotabova - One of the best experts on this subject based on the ideXlab platform.
-
low light induced violaxanthin de epoxidation in shortly preheated leaves uncoupling from δph dependent nonphotochemical quenching
Photochemistry and Photobiology, 2010Co-Authors: Petr Ilík, Martina Špundová, Eva Kotabova, Ondřej Novak, Radek Kaňa, Kazimierz StrzalkaAbstract:Plants protect themselves against excessive light by the induction of Delta pH-dependent nonphotochemical quenching (qE) that is associated with de-epoxidation of violaxanthin (V) to zeaxanthin (Z) in thylakoid membranes. In this work, we report that low light (12 micromol photons m(-2) s(-1)) is sufficient for a marked stimulation of the V to Z conversion in shortly preheated wheat leaves (5 min, 40 degrees C), but without a substantial increase in qE. Re-irradiation of these leaves with high light led to a rapid induction of nonphotochemical quenching, implying a potential photoprotective role of low-light-induced Z in preheated leaves. On the contrary to low light conditions, preheated leaves exposed to high light behaved similar to nonheated leaves with respect to the V to Z conversion and qE induction. The obtained results indicate that low-light-induced lumen acidification in preheated leaves is high enough to activate V de-epoxidation, but not sufficiently high to induce the formation of quenching centers.
-
Low‐light‐induced Violaxanthin De‐epoxidation in Shortly Preheated Leaves: Uncoupling from ΔpH‐dependent Nonphotochemical Quenching
Photochemistry and Photobiology, 2010Co-Authors: Petr Ilík, Martina Špundová, Eva Kotabova, Ondřej Novak, Radek Kaňa, Kazimierz StrzałkaAbstract:Plants protect themselves against excessive light by the induction of Delta pH-dependent nonphotochemical quenching (qE) that is associated with de-epoxidation of violaxanthin (V) to zeaxanthin (Z) in thylakoid membranes. In this work, we report that low light (12 micromol photons m(-2) s(-1)) is sufficient for a marked stimulation of the V to Z conversion in shortly preheated wheat leaves (5 min, 40 degrees C), but without a substantial increase in qE. Re-irradiation of these leaves with high light led to a rapid induction of nonphotochemical quenching, implying a potential photoprotective role of low-light-induced Z in preheated leaves. On the contrary to low light conditions, preheated leaves exposed to high light behaved similar to nonheated leaves with respect to the V to Z conversion and qE induction. The obtained results indicate that low-light-induced lumen acidification in preheated leaves is high enough to activate V de-epoxidation, but not sufficiently high to induce the formation of quenching centers.
