The Experts below are selected from a list of 5253 Experts worldwide ranked by ideXlab platform

Fengrui Sun - One of the best experts on this subject based on the ideXlab platform.

  • thermodynamic optimization principle for open inverse Brayton Cycle refrigeration heat pump Cycle
    Scientia Iranica, 2012
    Co-Authors: W. Zhang, Fengrui Sun
    Abstract:

    Abstract A thermodynamic model for an open inverse Brayton Cycle (refrigeration or heat pump Cycle) with pressure drop irreversibilities is established. There are seven flow resistances (or pressure drops) encountered by the working fluid stream for the inverse Brayton Cycle. Two of these, the friction through the blades and vanes of the compressor and the expander, are related to the isentropic efficiencies. The remaining flow resistances are always present because of the changes in flow cross-section at the compressor inlet and outlet, heat exchanger inlets and outlets and expander inlet and outlet. The analytical formulae about the cooling load of refrigeration Cycle, the heating load of heat pump Cycle and other coefficients are derived, which indicate that the thermodynamic performance for open inverse Brayton Cycle can be optimized by adjusting the mass flow rate (or the distribution of pressure losses along the flow path). It is shown that there are optimal air mass flow rates (or the distribution of pressure losses along the flow path) which maximize the cooling load of refrigeration Cycle, and the optimal air mass flow rates are smaller than the one at the maximum power output of the direct Brayton Cycle.

  • thermodynamic optimisation for open regenerated inverse Brayton Cycle refrigeration heat pump Cycle
    Journal of The Energy Institute, 2012
    Co-Authors: W. Zhang, Fengrui Sun
    Abstract:

    A thermodynamic model for an open regenerated inverse Brayton Cycle with pressure drop irreversibilities is established using finite time thermodynamics considering the size constraints of real plant in Part 1 of this paper. The analytical formulae about the cooling load and coefficient of performance of refrigeration Cycle, the heating load and coefficient of performance of heat pump Cycle are derived, which indicate that the thermodynamic performance for open regenerated inverse Brayton Cycle can be optimised by adjusting the mass flowrate. It is shown that the cooling load, heating load and the power input increase with the increase in the compressor inlet relative pressure drops, the coefficient of performance reaches its maximum at the optimal compressor ratio and the exhaust temperature is higher than that of the ambient, which is lower than that of the ambient only at small effectiveness of the regenerator.

  • power optimization of an endoreversible closed intercooled regenerated Brayton Cycle
    International Journal of Thermal Sciences, 2005
    Co-Authors: Wenhua Wang, Fengrui Sun
    Abstract:

    Abstract In this paper, power is optimized for an endoreversible closed intercooled regenerated Brayton Cycle coupled to constant-temperature heat reservoirs in the viewpoint of finite-time thermodynamics (FTT) or entropy generation minimization (EGM). The effects of some design parameters, including the Cycle heat reservoir temperature ratio and total heat exchanger inventory, on the maximum power and the corresponding efficiency are analyzed by numerical examples. The analysis shows that the Cycle dimensionless power can be optimized by searching the optimum heat conductance distributions among the hot- and cold-side heat exchangers, the regenerator and the intercooler for fixed total heat exchanger inventory, and by searching the optimum intercooling pressure ratio. When the optimization is performed with respect to the total pressure ratio of the Cycle, the maximum dimensionless power can be maximized again.

  • closed intercooled regenerator Brayton Cycle with constant temperature heat reservoirs
    Applied Energy, 2004
    Co-Authors: Wenhua Wang, Fengrui Sun
    Abstract:

    The performance of an irreversible closed intercooled regenerator Brayton-Cycle coupled to constant-temperature heat reservoirs is analyzed by using the theory of finite-time thermodynamics (FTT). Analytical formulae for dimensionless power and efficiency are derived. Especially, the intercooling pressure-ratio is optimized for the optimal power and the optimal efficiency, respectively. The effects of component (the intercooler, the regenerator, and the hot- and cold-side heat-exchangers) effectivenesses, the compressor and turbine efficiencies, the heat-reservoir temperature-ratio, and the temperature ratio of the cooling fluid in the intercooler and the cold-side heat reservoir on the optimal power and the corresponding efficiency and corresponding intercooling pressure ratio, as well as the optimal efficiency and the corresponding power and corresponding intercooling pressure-ratio are analyzed by detailed numerical examples.

  • Power Density Optimization for an Irreversible Closed Brayton Cycle
    Open Systems & Information Dynamics, 2001
    Co-Authors: Lingen Chen, Junlin Zheng, Fengrui Sun
    Abstract:

    In this paper, the power density, defined as the ratio of power output to the maximum specific volume in the Cycle, is taken as objective for performance optimization of an irreversible closed Brayton Cycle coupled to constant-temperature heat reservoirs in the viewpoint of finite time thermodynamics (FTT) or entropy generation minimization (EGM). The analytical formulas about the relations between power density and pressure ratio are derived with the heat resistance losses in the hot- and cold-side heat exchangers and the irreversible compression and expansion losses in the compressor and turbine. The maximum power density optimization is performed by searching the optimum heat conductance distribution corresponding to the optimum power density of the hot- and cold- side heat exchangers for the fixed heat exchanger inventory. The influence of some design parameters on the optimum heat conductance distribution, the maximum power density, and the optimum pressure ratio corresponding to the maximum power density are provided. The power plant design with optimization leads to a higher efficiency and smaller size including the compressor, turbine, and the hot- and cold-side heat exchangers.

Marc A Rosen - One of the best experts on this subject based on the ideXlab platform.

  • introducing and analysis of a hybrid molten carbonate fuel cell supercritical carbon dioxide Brayton Cycle system
    Sustainable Energy Technologies and Assessments, 2016
    Co-Authors: Fathollah Pourfayaz, Mehdi Mehrpooya, Parimah Bahramian, Marc A Rosen
    Abstract:

    Abstract A hybrid system is proposed, which integrates a molten carbonate fuel cell, and a supercritical carbon dioxide Brayton Cycle. This case deals with waste heat recovery from catalytic burner exhaust gas using a Brayton Cycle as a bottoming Cycle for additional power production due its very high temperature, which yields high electrical and overall efficiencies. After designing and simulating the process energy and exergy analyses are performed. The greatest exergy destruction is observed in the reformer while the lowest exergy efficiency is attributable to the fuel cell. The main advantage of this kind of hybrid system, in addition to efficiency improvement and cost reduction, is its ability to reduce harmful emissions and negative impacts on the environment.

Mehdi Mehrpooya - One of the best experts on this subject based on the ideXlab platform.

  • introducing and analysis of a hybrid molten carbonate fuel cell supercritical carbon dioxide Brayton Cycle system
    Sustainable Energy Technologies and Assessments, 2016
    Co-Authors: Fathollah Pourfayaz, Mehdi Mehrpooya, Parimah Bahramian, Marc A Rosen
    Abstract:

    Abstract A hybrid system is proposed, which integrates a molten carbonate fuel cell, and a supercritical carbon dioxide Brayton Cycle. This case deals with waste heat recovery from catalytic burner exhaust gas using a Brayton Cycle as a bottoming Cycle for additional power production due its very high temperature, which yields high electrical and overall efficiencies. After designing and simulating the process energy and exergy analyses are performed. The greatest exergy destruction is observed in the reformer while the lowest exergy efficiency is attributable to the fuel cell. The main advantage of this kind of hybrid system, in addition to efficiency improvement and cost reduction, is its ability to reduce harmful emissions and negative impacts on the environment.

Youcai Liang - One of the best experts on this subject based on the ideXlab platform.

  • theoretical analysis of a regenerative supercritical carbon dioxide Brayton Cycle organic rankine Cycle dual loop for waste heat recovery of a diesel natural gas dual fuel engine
    Energy Conversion and Management, 2019
    Co-Authors: Youcai Liang, Xingyan Bian, Weiwei Qian, Mingzhang Pan, Zhibo Ban
    Abstract:

    Abstract Supercritical carbon dioxide Brayton Cycle is considered one of the most promising systems for waste heat recovery of engines because of its compactness and high energy efficiency. To further improve the fuel utilization ratio and solve the difficulties of waste heat recovery of high temperature exhaust gas, a regenerative supercritical carbon dioxide Brayton Cycle/organic Rankine Cycle dual loop is proposed for cascade utilization of exhaust heat from a dual-fuel engine. The regenerative supercritical carbon dioxide Brayton Cycle of the proposed system is powered by the waste heat contained in the exhaust gas. The working fluid in the organic Rankine Cycle is pre-heated by CO2 exiting the regenerator and then further heated by the residual heat of the exhaust gas. The flow rates of the working fluids in both sub Cycles are adjusted to match the waste heat recovery system to respond to the changing conditions of the dual-fuel engine. The results revealed that the maximum net power output of this system is up to 40.88 kW, thus improving the dual-fuel engine power output by 6.78%. Therefore, such a regenerative supercritical carbon dioxide Brayton Cycle/organic Rankine Cycle dual loop system design enables the thorough recovery of high temperature exhaust heat, leading to higher energy efficiency and lower fuel consumption of the engine.

Zha Liu - One of the best experts on this subject based on the ideXlab platform.

  • advanced exergoeconomic evaluation on supercritical carbon dioxide recompression Brayton Cycle
    Journal of Cleaner Production, 2020
    Co-Authors: Zha Liu, Zihui Liu, Xing Cao, Tao Luo, Xiaohu Yang
    Abstract:

    Abstract This study proposes a comprehensive understanding of the supercritical carbon dioxide recompression Brayton Cycle by means of extending and applying the advanced exergoeconomic method as one of the first attempts. The advantages of this advanced exergy-based method are determining the real potential for improvement of each significant component and considering the interactions among system components, which cannot be achieved by using the conventional method. The unavoidable/avoidable and endogenous/exogenous concepts are introduced, and detailed modeling is performed to calculate exergy destruction and investment costs. The results demonstrate that the unavoidable value of each component is higher than the avoidable value for exergy destruction cost (except for high temperature recuperator). Even under the most optimistic scenario, the total exergy destruction cost can only be reduced by 2199.29 $/h (38.86%), and about half of this avoidable variable is exogenous. According to the results of traditional exergoeconomic analysis, the reactor is recommended as the governing component to improve the cost effectiveness of the Cycle due mainly to its highest operating cost (5313.39 $/h). On the contrast, the turbine should have the highest improvement priority owing to the highest value of the avoidable operating cost (1390.88 $/h). The findings provide a novel way to guide the design and evaluation of the carbon dioxide Brayton Cycle through benefiting from the advanced exergoeconomic analysis.