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Hanfei Tuo - One of the best experts on this subject based on the ideXlab platform.

  • thermal economic analysis of a transcritical rankine power Cycle with Reheat enhancement for a low grade heat source
    International Journal of Energy Research, 2013
    Co-Authors: Hanfei Tuo
    Abstract:

    SUMMARY A thermal-economic analysis of a transcritical Rankine power Cycle with Reheat enhancement using a low-grade industrial waste heat is presented. Under the identical operating conditions, the Reheat Cycle is compared to the non-Reheat baseline Cycle with respect to the specific net power output, the thermal efficiency, the heat exchanger area, and the total capital costs of the systems. Detailed parametric effects are investigated in order to maximize the Cycle performance and minimize the system unit cost per net work output. The main results show that the value of the optimum Reheat pressure maximizing the specific net work output is approximately equal to the one that causes the same expansion ratio across each stage turbine. Relative performance improvement by Reheat process over the baseline is augmented with an increase of the high pressure but a decrease of the turbine inlet temperature. Enhancement for the specific net work output is more significant than that for the thermal efficiency under each condition, because total heat input is increased in the Reheat Cycle for the Reheat process. The economic analysis reveals that the respective optimal high pressures minimizing the unit heat exchanger area and system cost are much lower than that maximizing the energy performance. The comparative analysis identifies the range of operating conditions when the proposed Reheat Cycle is more cost effective than the baseline. Copyright © 2012 John Wiley & Sons, Ltd.

  • Thermodynamic and Economic Analysis of Reheat Transcritical Organic Rankine Power Cycle Using a Low Temperature Geothermal Heat Source
    Volume 4: Codes Standards Licensing and Regulatory Issues; Fuel Cycle Radioactive Waste Management and Decommissioning; Computational Fluid Dynamics (, 2012
    Co-Authors: Hanfei Tuo
    Abstract:

    A revision of transcritical power Cycle with Reheat enhancement is proposed in this paper. Energy analysis is carried out to investigate parametric effects on Cycle performance, and further detailed cost and economic analysis is conducted to evaluate the feasibility of the Reheat Cycle in practical applications. CO2 is chosen as the working fluid and heat source is from the geothermal energy in the present study. Results show that Reheat pressure is a very important parameter affecting the Cycle performance, and its optimal value corresponding to the maximum Cycle performance is that makes the same expansion ratio across each stage turbine. There is more potential for regeneration enhancement in the Reheat Cycle, since the exhaust out of the turbine has a higher temperature than without Reheat.From the economic analysis and optimization, it is found that in both Cycles the cost minimization is obtained at a corresponding optimal value of the high pressure which is significantly lower than that maximizing the Cycle performance based on the first law of thermodynamics. This is due to the fact that the turbine and pump costs are dominant over other major components considered and their costs increase significant with the high operating pressure. The comparison of their unit costs reveal the existence of a critical high pressure for a given turbine inlet temperature Th above which Reheat Cycle is more cost effective than the baseline. And this value of the critical pressure increases with Th.Overall, Reheat enhancement method has great potential to improve thermal efficiency and especially net work output of transcritical power Cycle using a low-grade geothermal heat source.Copyright © 2012 by ASME

  • Thermal‐economic analysis of a transcritical Rankine power Cycle with Reheat enhancement for a low‐grade heat source
    International Journal of Energy Research, 2012
    Co-Authors: Hanfei Tuo
    Abstract:

    SUMMARY A thermal-economic analysis of a transcritical Rankine power Cycle with Reheat enhancement using a low-grade industrial waste heat is presented. Under the identical operating conditions, the Reheat Cycle is compared to the non-Reheat baseline Cycle with respect to the specific net power output, the thermal efficiency, the heat exchanger area, and the total capital costs of the systems. Detailed parametric effects are investigated in order to maximize the Cycle performance and minimize the system unit cost per net work output. The main results show that the value of the optimum Reheat pressure maximizing the specific net work output is approximately equal to the one that causes the same expansion ratio across each stage turbine. Relative performance improvement by Reheat process over the baseline is augmented with an increase of the high pressure but a decrease of the turbine inlet temperature. Enhancement for the specific net work output is more significant than that for the thermal efficiency under each condition, because total heat input is increased in the Reheat Cycle for the Reheat process. The economic analysis reveals that the respective optimal high pressures minimizing the unit heat exchanger area and system cost are much lower than that maximizing the energy performance. The comparative analysis identifies the range of operating conditions when the proposed Reheat Cycle is more cost effective than the baseline. Copyright © 2012 John Wiley & Sons, Ltd.

  • Thermodynamic analysis of performance improvement by Reheat on the CO2 transcritical power Cycle
    2012
    Co-Authors: Hanfei Tuo
    Abstract:

    The CO2 transcritical rankine power Cycle has been widely investigated recently, because of its better temperature glide matching between sensible heat source and working fluid in vapor generator, and its desirable qualities, such as moderate critical point, little environment impact and low cost. A Reheat CO2 transcritical power Cycle with two stage expansion is presented to improve baseline Cycle performance in this paper. Energy and exergy analysis are carried out to investigate effects of important parameters on Cycle performance. The main results show that Reheat Cycle performance is sensitive to the variation of medium pressures and the optimum medium pressures exist for maximizing work output and thermal efficiency, respectively. Reheat Cycle is compared to baseline Cycle under the same conditions. More significant improvements by Reheat are obtained at lower turbine inlet temperatures and larger high Cycle pressure. Work output improvement is much higher than thermal efficiency improvement, because extra waste heat is required to Reheat CO2. Based on second law analysis, exergy efficiency of Reheat Cycle is also higher than that of baseline Cycle, because more useful work is converted from waste heat. Reheat with two stage expansion has great potential to improve thermal efficiency and especially net work output of a CO2 transcritical power Cycle using a low-grade heat source.

  • Analysis of a Reheat Carbon Dioxide Transcritical Power Cycle Using a Low Temperature Heat Source
    Volume 4: Energy Systems Analysis Thermodynamics and Sustainability; Combustion Science and Engineering; Nanoengineering for Energy Parts A and B, 2011
    Co-Authors: Hanfei Tuo
    Abstract:

    The CO2 transcritical Rankine power Cycle has been widely investigated recently, because of its better temperature glide matching between sensible heat source and working fluid in vapor generator, and its desirable qualities, such as moderate critical point, little environment impact and low cost. A Reheat CO2 transcritical power Cycle with two stage expansion is presented to improve baseline Cycle performance in this paper. Energy and exergy analysis are carried out to investigate parametric effects on Cycle performance. The main results show that Reheat Cycle performance is sensitive to the medium pressures and the optimum pressures exist for maximizing net work output and thermal efficiency, respectively. Reheat Cycle is compared to baseline Cycle under the same conditions. More significant improvements by Reheat are obtained at lower turbine inlet temperatures and/or larger high Cycle pressure. Work output improvement is much higher than thermal efficiency improvement, because extra waste heat is required to Reheat CO2. Based on second law analysis, exergy efficiency of Reheat Cycle is also higher than that of baseline Cycle, because more useful work is converted from waste heat. Reheat with two stage expansion has great potential to improve thermal efficiency and especially net work output of a CO2 transcritical power Cycle using a low-grade heat source.

A. M. Bassily - One of the best experts on this subject based on the ideXlab platform.

  • analysis and cost optimization of the triple pressure steam Reheat gas Reheat gas recuperated combined power Cycle
    International Journal of Energy Research, 2008
    Co-Authors: A. M. Bassily
    Abstract:

    Increasing the inlet temperature of gas turbine (TIT) and optimization are important methods for improving the efficiency and power of the combined Cycle. In this paper, the triple-pressure steam-Reheat gas-Reheat recuperated combined Cycle (the Regular Gas-Reheat Cycle) was optimized relative to its operating parameters, including the temperature differences for pinch points (δTPP). The optimized triple-pressure steam-Reheat gas-Reheat recuperated combined Cycle (the Optimized Cycle) had much lower δTPP than that for the Regular Gas-Reheat Cycle so that the area of heat transfer of the heat recovery steam generator (HRSG) of the Optimized Cycle had to be increased to keep the same rate of heat transfer. For the same mass flow rate of air, the Optimized Cycle generates more power and consumes more fuel than the Regular Gas-Reheat Cycle. An objective function of the net additional revenue (the saving of the optimization process) was defined in terms of the revenue of the additional generated power and the costs of replacing the HRSG and the additional fuel. Constraints were set on many operating parameters such as the minimum temperature difference for pinch points (δTPPm), the steam turbines inlet temperatures and pressures, and the dryness fraction at steam turbine outlet. The net additional revenue was optimized at 11 different maximum values of TIT using two different methods: the direct search and variable metric. The performance of the Optimized Cycle was compared with that for the Regular Gas-Reheat Cycle and the triple-pressure steam-Reheat gas-Reheat recuperated reduced-irreversibility combined Cycle (the Reduced-Irreversibility Cycle). The results indicate that the Optimized Cycle is 0.17–0.35 percentage point higher in efficiency and 5.3–6.8% higher in specific work than the Reduced-Irreversibility Cycle, which is 2.84–2.91 percentage points higher in efficiency and 4.7% higher in specific work than the Regular Gas-Reheat Cycle when all Cycles are compared at the same values of TIT and δTPPm. Optimizing the net additional revenue could result in an annual saving of 33.7 million US dollars for a 481 MW power plant. The Optimized Cycle was 3.62 percentage points higher in efficiency than the most efficient commercially available H-system combined Cycle when compared at the same value of TIT. Copyright © 2007 John Wiley & Sons, Ltd.

  • Enhancing the efficiency and power of the triple-pressure Reheat combined Cycle by means of gas Reheat, gas recuperation, and reduction of the irreversibility in the heat recovery steam generator
    Applied Energy, 2008
    Co-Authors: A. M. Bassily
    Abstract:

    Abstract The main methods for improving the efficiency or power of the combined Cycle are: increasing the inlet temperature of the gas turbine (TIT), inlet air-cooling, applying gas Reheat, steam or water injection into the gas turbine (GT), and reducing the irreversibility of the heat recovery steam generator (HRSG). In this paper, gas Reheat with recuperation was applied to the regular triple-pressure steam-Reheat combined Cycle (the Regular Cycle) by replacing the GT unit with a recuperated gas-Reheat GT unit (requires two gas turbines, gas recuperator, and two combustion chambers). The Regular Cycle with gas-Reheat and gas-recuperation (the Regular Gas Reheat Cycle) was modeled including detailed modeling of the combustion and GT cooling processes and a feasible technique to reduce the irreversibility of its HRSG was introduced. The Regular Gas Reheat Cycle and the Regular Gas Reheat Cycle with reduced-irreversibility HRSG (the Reduced Irreversibility Cycle) were compared with the Regular Cycle, which is the typical design for a commercial combined Cycle. The effects of varying the TIT on the performances of all Cycles were presented and discussed. The results indicate that the Reduced Irreversibility Cycle is 1.9–2.15 percentage points higher in efficiency and 3.5% higher in the total specific work than the Regular Gas Reheat Cycle, which is 3.3–3.6 percentage points higher in efficiency and 22–26% higher in the total specific work than the Regular Cycle. The Regular Gas Reheat and Reduced Irreversibility Cycles are 1.18 and 3.16 percentage points; respectively, higher in efficiency than the most efficient commercially-available combined Cycle at the same value of TIT. Economic analysis was performed and showed that applying gas Reheat with recuperation to the Regular Cycle could result in an annual saving of 10.2 to 11.2 million US dollars for a 339 MW to 348 MW generating unit using the Regular Cycle and that reducing the irreversibility of the HRSG of the Regular Gas Reheat Cycle could result in an additional annual saving of 11.8 million US dollars for a 439 MW generating unit using the Regular Gas Reheat Cycle.

  • Analysis and cost optimization of the triple‐pressure steam‐Reheat gas‐Reheat gas‐recuperated combined power Cycle
    International Journal of Energy Research, 2008
    Co-Authors: A. M. Bassily
    Abstract:

    Increasing the inlet temperature of gas turbine (TIT) and optimization are important methods for improving the efficiency and power of the combined Cycle. In this paper, the triple-pressure steam-Reheat gas-Reheat recuperated combined Cycle (the Regular Gas-Reheat Cycle) was optimized relative to its operating parameters, including the temperature differences for pinch points (δTPP). The optimized triple-pressure steam-Reheat gas-Reheat recuperated combined Cycle (the Optimized Cycle) had much lower δTPP than that for the Regular Gas-Reheat Cycle so that the area of heat transfer of the heat recovery steam generator (HRSG) of the Optimized Cycle had to be increased to keep the same rate of heat transfer. For the same mass flow rate of air, the Optimized Cycle generates more power and consumes more fuel than the Regular Gas-Reheat Cycle. An objective function of the net additional revenue (the saving of the optimization process) was defined in terms of the revenue of the additional generated power and the costs of replacing the HRSG and the additional fuel. Constraints were set on many operating parameters such as the minimum temperature difference for pinch points (δTPPm), the steam turbines inlet temperatures and pressures, and the dryness fraction at steam turbine outlet. The net additional revenue was optimized at 11 different maximum values of TIT using two different methods: the direct search and variable metric. The performance of the Optimized Cycle was compared with that for the Regular Gas-Reheat Cycle and the triple-pressure steam-Reheat gas-Reheat recuperated reduced-irreversibility combined Cycle (the Reduced-Irreversibility Cycle). The results indicate that the Optimized Cycle is 0.17–0.35 percentage point higher in efficiency and 5.3–6.8% higher in specific work than the Reduced-Irreversibility Cycle, which is 2.84–2.91 percentage points higher in efficiency and 4.7% higher in specific work than the Regular Gas-Reheat Cycle when all Cycles are compared at the same values of TIT and δTPPm. Optimizing the net additional revenue could result in an annual saving of 33.7 million US dollars for a 481 MW power plant. The Optimized Cycle was 3.62 percentage points higher in efficiency than the most efficient commercially available H-system combined Cycle when compared at the same value of TIT. Copyright © 2007 John Wiley & Sons, Ltd.

E. L. Resler - One of the best experts on this subject based on the ideXlab platform.

  • Wave Cycle Design for Wave Rotor Gas Turbine Engines With Low NOx Emissions
    Journal of Engineering for Gas Turbines and Power, 1996
    Co-Authors: M. R. Nalim, E. L. Resler
    Abstract:

    The wave rotor is a promising means of pressure-gain for gas turbine engines. This paper examines novel wave rotor topping Cycles that incorporate low-NO x combustion strategies. This approach combines two-stage rich-quench-lean (RQL) combustion with intermediate expansion in the wave rotor to extract energy and reduce the peak stoichiometric temperature substantially. The thermodynamic Cycle is a type of Reheat Cycle, with the rich-zone air undergoing a high-pressure stage. Rich-stage combustion could occur external to or within the wave rotor. An approximate analytical design method and CFD/combustion codes are used to develop and simulate wave rotor flow Cycles. Engine Cycles designed with a bypass turbine and external combustion demonstrate a performance enhancement equivalent to a 200-400 R (110-220 K) increase in turbine inlet temperature. The stoichiometric combustion temperature is reduced by 300-450 R (170-250 K) relative to an equivalent simple Cycle, implying substantially reduced NO x formation.

  • Wave Cycle Design for Wave Rotor Gas Turbine Engines With Low NOx Emissions
    Volume 2: Aircraft Engine; Marine; Microturbines and Small Turbomachinery, 1995
    Co-Authors: M. R. Nalim, E. L. Resler
    Abstract:

    The wave rotor is a promising means of pressure-gain for gas turbine engines. This paper examines novel wave rotor topping Cycles which incorporate low-NOx combustion strategies. This approach combines two-stage ‘rich-quench-lean’ (RQL) combustion with intermediate expansion in the wave rotor to extract energy and reduce the peak stoichiometric temperature substantially. The thermodynamic Cycle is a type of Reheat Cycle, with the rich-zone air undergoing a high pressure stage. Rich-stage combustion could occur external to or within the wave rotor.An approximate analytical design method and CFD/combustion codes are used to develop and simulate wave rotor flow Cycles. Engine Cycles designed with a bypass turbine and external combustion demonstrate a performance enhancement equivalent to a 200–400°R (110–220°K) increase in turbine inlet temperature. The stoichiometric combustion temperature is reduced by 300–450°R (170–250°K) relative to an equivalent simple Cycle, implying substantially reduced NOx formation.Copyright © 1995 by ASME

M. R. Nalim - One of the best experts on this subject based on the ideXlab platform.

  • Wave Cycle Design for Wave Rotor Gas Turbine Engines With Low NOx Emissions
    Journal of Engineering for Gas Turbines and Power, 1996
    Co-Authors: M. R. Nalim, E. L. Resler
    Abstract:

    The wave rotor is a promising means of pressure-gain for gas turbine engines. This paper examines novel wave rotor topping Cycles that incorporate low-NO x combustion strategies. This approach combines two-stage rich-quench-lean (RQL) combustion with intermediate expansion in the wave rotor to extract energy and reduce the peak stoichiometric temperature substantially. The thermodynamic Cycle is a type of Reheat Cycle, with the rich-zone air undergoing a high-pressure stage. Rich-stage combustion could occur external to or within the wave rotor. An approximate analytical design method and CFD/combustion codes are used to develop and simulate wave rotor flow Cycles. Engine Cycles designed with a bypass turbine and external combustion demonstrate a performance enhancement equivalent to a 200-400 R (110-220 K) increase in turbine inlet temperature. The stoichiometric combustion temperature is reduced by 300-450 R (170-250 K) relative to an equivalent simple Cycle, implying substantially reduced NO x formation.

  • Wave Cycle Design for Wave Rotor Gas Turbine Engines With Low NOx Emissions
    Volume 2: Aircraft Engine; Marine; Microturbines and Small Turbomachinery, 1995
    Co-Authors: M. R. Nalim, E. L. Resler
    Abstract:

    The wave rotor is a promising means of pressure-gain for gas turbine engines. This paper examines novel wave rotor topping Cycles which incorporate low-NOx combustion strategies. This approach combines two-stage ‘rich-quench-lean’ (RQL) combustion with intermediate expansion in the wave rotor to extract energy and reduce the peak stoichiometric temperature substantially. The thermodynamic Cycle is a type of Reheat Cycle, with the rich-zone air undergoing a high pressure stage. Rich-stage combustion could occur external to or within the wave rotor.An approximate analytical design method and CFD/combustion codes are used to develop and simulate wave rotor flow Cycles. Engine Cycles designed with a bypass turbine and external combustion demonstrate a performance enhancement equivalent to a 200–400°R (110–220°K) increase in turbine inlet temperature. The stoichiometric combustion temperature is reduced by 300–450°R (170–250°K) relative to an equivalent simple Cycle, implying substantially reduced NOx formation.Copyright © 1995 by ASME

Pyong Sik Pak - One of the best experts on this subject based on the ideXlab platform.

  • Characteristics and Economics Evaluation of an H2O Turbine Reheat Cycle Power Generation System Based on Oxy-Combustion Method for Utilizing Exhaust Gas of Large Scale MCFC
    Journal of International Council on Electrical Engineering, 2011
    Co-Authors: Pyong Sik Pak, Young Duk Lee, Kook Young Ahn
    Abstract:

    AbstractA large scale MCFC (48 MW) was adopted to construct a high-efficiency and economic power generation system without CO2 emission for utilizing its exhaust gas. A conventional steam turbine power generation system (STPS) is evaluated and the net generated power increase rate (NPIR) is estimated to be 8.22% and the STPS is economically feasible. A new CO2-capturing repowering system with Reheat Cycle is proposed: in the proposed system, saturated steam produced at a HRSG by using the MCFC exhaust gas is utilized as a main working fluid of a gas (H2O gas) turbine, and the temperature of the steam is raised by combusting fuel in a combustor by using pure oxygen instead of air. It is estimated that the NPIR of the proposed system is 24.4%, and the CO2 reduction amount is 27.0 kt-CO2/y, compared to that (9.09 kt-CO2/y) of the STPS, and that the proposed system surpasses the STPS in terms of economics.

  • characteristic evaluation of a co2 capturing repowering system based on oxy fuel combustion and exergetic flow analyses for improving efficiency
    International Journal of Energy Research, 2010
    Co-Authors: Pyong Sik Pak, Young Duk Lee, Kook Young Ahn
    Abstract:

    A CO2-capturing H2O turbine power generation system based on oxy-fuel combustion method is proposed to decrease CO2 emission from an existing thermal power generation system (TPGS) by utilizing steam produced in the TPGS. A high efficient combined Cycle power generation system (CCPS) with Reheat Cycle is adopted as an example of existing TPGSs into which the proposed system is retrofitted. First, power generation characteristics of the proposed CO2-capturing system, which requires no modification of the CCPS itself, are estimated. It is shown through simulation study that the proposed system can reduce 26.8% of CO2 emission with an efficiency decrease by 1.20% and an increase power output by 23.2%, compared with the original CCPS. Second, in order to improve power generation characteristics and CO2 reduction effect of the proposed system, modifications of the proposed system are investigated based on exergetic flow analyses, and revised systems are proposed based on the obtained results. Finally, it is shown that a revised proposed system, which has the same turbine inlet temperature as the CCPS, can increase power output by 33.6%, and reduce 32.5% of CO2 emission with exergetic efficiency decrease by 1.58%, compared with the original CCPS. Copyright © 2010 John Wiley & Sons, Ltd.

  • characteristics evaluation of a co2 capturing power generation system with Reheat Cycle utilizing regenerative oxygen combustion steam superheater
    Electrical Engineering in Japan, 2008
    Co-Authors: Pyong Sik Pak
    Abstract:

    A new CO2-capturing power generation system is proposed that can be easily realized by applying conventional technologies. In the proposed system, the temperature of medium-pressure steam in a thermal power plant is raised by utilizing an oxygen-combusting regenerative steam-superheater. The CO2 generated by combusting the fuel in the superheater can be easily separated and captured from the exhaust gas at the condenser outlet, and is liquefied. The superheated steam is used to drive a steam turbine power generation system. Using a high-efficiency combined Cycle power generation system as an example, it is shown that the proposed system can increase the power output by 10.8%, and decrease the CO2 emissions of the entire integrated system by 18.6% with a power generation efficiency drop of 2.36% compared with the original power plant without CO2 capture, when the superheated steam temperature is 750 °C. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(1): 35–41, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20575

  • Characteristics evaluation of a CO2‐capturing power generation system with Reheat Cycle utilizing regenerative oxygen‐combustion steam‐superheater
    Electrical Engineering in Japan, 2008
    Co-Authors: Pyong Sik Pak
    Abstract:

    A new CO2-capturing power generation system is proposed that can be easily realized by applying conventional technologies. In the proposed system, the temperature of medium-pressure steam in a thermal power plant is raised by utilizing an oxygen-combusting regenerative steam-superheater. The CO2 generated by combusting the fuel in the superheater can be easily separated and captured from the exhaust gas at the condenser outlet, and is liquefied. The superheated steam is used to drive a steam turbine power generation system. Using a high-efficiency combined Cycle power generation system as an example, it is shown that the proposed system can increase the power output by 10.8%, and decrease the CO2 emissions of the entire integrated system by 18.6% with a power generation efficiency drop of 2.36% compared with the original power plant without CO2 capture, when the superheated steam temperature is 750 °C. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(1): 35–41, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20575