The Experts below are selected from a list of 186 Experts worldwide ranked by ideXlab platform

Koichi Ito - One of the best experts on this subject based on the ideXlab platform.

  • structural optimization of an energy supply system from economic viewpoint
    Jsme International Journal Series B-fluids and Thermal Engineering, 2004
    Co-Authors: Satoshi Gamou, Ryohei Yokoyama, Koichi Ito, Shu Yoshida
    Abstract:

    An optimal planning method of system structure is proposed to determine kinds, numbers and capacities of equipment for an energy supply system installed in commercial and public buildings from economic viewpoint. In this method, they are determined together with maximum contract demands of utilities such as electricity and natural gas so as to minimize the Annual Total Cost in consideration of system's Annual operational strategies corresponding to seasonal and hourly energy demand requirements. A numerical study is carried out for an office building with Total floor area of 15 000 m 2 . Through the study, the following are clarified: (a) the optimal system structure for the office building; (b) the economic effects of the optimal system compared to other typical energy supply systems; (c) the influence on the optimal system structure of the future efficiency improvement and initial capital Cost reduction of equipment.

  • effect of inlet air cooling by ice storage on unit sizing of a gas turbine cogeneration plant
    Journal of Engineering for Gas Turbines and Power-transactions of The Asme, 2004
    Co-Authors: Ryohei Yokoyama, Koichi Ito
    Abstract:

    In the commercial sector, heat and power demands peak in the summer daytime because of high space cooling demands, and cogeneration plants are required to produce maximum heat and power to meet their demands. However, gas turbine cogeneration plants have the disadvantage of decreases in maximum power output in the summer daytime, which reduces the availability of gas turbines. One of the ways to avoid the aforementioned disadvantage is to cool inlet air and augment maximum power output. In addition, one of the ways for inlet air cooling is to make ice by driving electric compression refrigerators using off-peak power generated during the nighttime, store it in ice banks, and use its heat for inlet air cooling during the on-peak period. The objective of this paper is to investigate the effect of inlet air cooling by ice storage on the unit sizing and Cost of a gas turbine cogeneration plant. An optimal unit sizing method based on the mixed-integer linear programming is used to rationally determine equipment capacities and operational strategies of the plant. A numerical study is conducted, in which the gas turbine cogeneration plants with and without inlet air cooled by ice storage are compared with each other, and the effect of inlet air cooling on the equipment capacities as well as the Annual Total Cost and its items is clarified.

  • optimal unit sizing of cogeneration systems in consideration of uncertain energy demands as continuous random variables
    Energy Conversion and Management, 2002
    Co-Authors: Satoshi Gamou, Ryohei Yokoyama, Koichi Ito
    Abstract:

    Abstract An optimal unit sizing method for cogeneration systems is proposed using energy demands as continuous random variables. In this method, design variables such as equipment capacities and maximum contract utility demands are determined together with the systems' operational strategies so as to minimize an expected value of the Annual Total Cost subject to the satisfaction of all the possible energy demands. In evaluating the expected value, decision variables and the objective function are considered as piece-wise linear functions of energy demands by applying a sensitivity analysis in linear programming and an enumeration method in mixed-integer programming. This optimization problem is formulated and solved based on a hierarchical optimization algorithm. A numerical study is carried out on a fuel cell cogeneration system installed in an office building. Through the study, the influence of uncertainties in energy demands on a system's economics and optimal equipment capacities are clarified.

  • effect of inlet air cooling by ice storage on unit sizing of a gas turbine cogeneration plant
    ASME Turbo Expo 2002: Power for Land Sea and Air, 2002
    Co-Authors: Ryohei Yokoyama, Koichi Ito
    Abstract:

    In the commercial sector, heat and power demands peak in the summer daytime because of high space cooling demands, and cogeneration plants are required to produce maximum heat and power to meet their demands. However, gas turbine cogeneration plants have the disadvantage of decreases in maximum power output in the summer daytime, which reduces the availability of gas turbines. One of the ways to avoid the aforementioned disadvantage is to cool inlet air and augment maximum power output. In addition, one of the ways for inlet air cooling is to make ice by driving electric compression refrigerators using off-peak power generated during the nighttime, store it in ice banks, and use its heat for inlet air cooling during the on-peak period. The objective of this paper is to investigate the effect of inlet air cooling by ice storage on the unit sizing and Cost of a gas turbine cogeneration plant. An optimal unit sizing method based on the mixed-integer linear programming is used to rationally determine equipment capacities and operational strategies of the plant. A numerical study is conducted, in which the gas turbine cogeneration plants with and without inlet air cooled by ice storage are compared with each other, and the effect of inlet air cooling on the equipment capacities as well as the Annual Total Cost and its items is clarified.Copyright © 2002 by ASME

  • optimal unit sizing of cogeneration systems under the toleration for shortage of energy supply
    International Journal of Energy Research, 2000
    Co-Authors: Satoshi Gamou, Ryohei Yokoyama, Koichi Ito
    Abstract:

    The paper investigates the influence of tolerating the shortage of energy supplies on the economy of cogeneration systems in consideration of energy demands as random variables. To make a reasonable investigation into the influence, an optimal unit sizing method proposed by the authors is adopted after it is extended to this case so that it enables probability distributions of energy demands to be considered. In the method, equipment capacities and maximum contract demands of utilities such as electricity and natural gas are determined so as to minimize the expected value of the Annual Total Cost in consideration of operational strategies for all the estimated energy demands under the toleration for the shortage of energy supplies. Numerical studies are carried out on cogeneration systems installed in a hotel or an office building with changing shortage rates of energy supplies as parameters. Through the studies, it is found that the expected systems' economy is improved even if the shortage rates of energy supplies are very small, and that the improvement for the office building is larger than that for the hotel. Copyright © 2000 John Wiley & Sons, Ltd.

Guoqiang Zhang - One of the best experts on this subject based on the ideXlab platform.

  • optimization analysis of a novel combined heating and power system based on biomass partial gasification and ground source heat pump
    Energy Conversion and Management, 2018
    Co-Authors: Xiaofeng Zhang, Lifang Liu, Chengying Bai, Shuang Wang, Quanbin Song, Jing Zeng, Xiaobo Liu, Guoqiang Zhang
    Abstract:

    Abstract The thermodynamic performance of a novel combined heating and power system integrated with biomass partial gasification and ground source heat pump has been investigated previously, while system performances are greatly dependent on system component capacity and operation strategy. In this paper, a multi-objective optimization model of proposed integration system is presented, which considers the energetic, economic and environmental performances. The optimal parameters are mainly consists of three parts: the rated power of power generation unit, carbon conversion ratio and the temperature of warm water. Genetic algorithm is adopted to optimize the component capacity and operation strategy of proposed system. In order to demonstrate the optimal model, a case study is adopted. The optimal results show that the primary energy saving ratio, Annual Total Cost saving ratio, carbon dioxide emission reduction ratio and performance indicator are 7.61%, 23.62%, 66.52%, 32.58%, respectively. In addition, the influences of related economic factors on proposed system performances are also analyzed. Finally, the research shows that the multi-objective optimization model provides a new way for the optimization design of the integration system.

  • analysis of a feasible trigeneration system taking solar energy and biomass as co feeds
    Energy Conversion and Management, 2016
    Co-Authors: Xiaofeng Zhang, Hongqiang Li, Rong Zeng, Guoqiang Zhang
    Abstract:

    Abstract The trigeneration systems are widely used owing to high efficiency, low greenhouse gas emission and high reliability. Especially, those trigeneration systems taking renewable energy as primary input are paid more and more attention. This paper presents a feasible trigeneration system, which realizes biomass and solar energy integrating effective utilization according to energy cascade utilization and energy level upgrading of chemical reaction principle. In the proposed system, the solar energy with mid-and-low temperature converted to the chemical energy of bio-gas through gasification process, then the bio-gas will be taken as the fuel for internal combustion engine (ICE) to generate electricity. The jacket water as a byproduct generated from ICE is utilized in a liquid desiccant unit for providing desiccant capacity. The flue gas is transported into an absorption chiller and heat exchanger consequently, supplying chilled water and domestic hot water. The thermodynamic performance of the trigeneration system was investigated by the help of Aspen plus. The results indicate that the overall energy efficiency and the electrical efficiency of the proposed system in case study are 77.4% and 17.8%, respectively. The introduction of solar energy decreases the consumption of biomass, and the solar thermal energy input fraction is 8.6%. In addition, the primary energy saving ratio and Annual Total Cost saving ratio compared with the separated generation system are 16.7% and 25.9%, respectively.

Ryohei Yokoyama - One of the best experts on this subject based on the ideXlab platform.

  • thermoeconomic analysis and optimization of a gas turbine cogeneration unit by a systems approach
    ASME Turbo Expo 2005: Power for Land Sea and Air, 2005
    Co-Authors: Ryohei Yokoyama, Shinsuke Takeuchi, Koichi Ito
    Abstract:

    It is important to design and operate energy conversion systems such as gas turbine cogeneration ones optimally from the thermoeconomic viewpoint. However, an energy conversion system has a complex network structure, and it takes much time to create its model for the thermoeconomic analysis and optimization. In this paper, a systems approach is presented for the performance analysis and optimization of mechanical systems with network structures, and it is applied to the thermoeconomic analysis and optimization of a gas turbine cogeneration unit. The system modeling for the performance analysis is conducted by a building block approach. Static and dynamic problems for the performance analysis are formulated as sets of nonlinear algebraic and differential algebraic equations, and are solved by the Newton-Raphson method and a hierarchical combination of the Runge-Kutta and Newton-Raphson methods, respectively. The performance optimization is conducted to determine design and operation conditions which optimize performance criteria. This problem is formulated as a nonlinear programming one and is solved by a global optimization method. In the application, the cycle analysis is conducted to determine mass flow rates, pressures, and temperatures, which is followed by the exergy and Cost analyses to determine exergy flow rates and efficiencies, and capital Costs, respectively. In addition, design and operation conditions are determined to maximize the exergy efficiency or minimize the Annual Total Cost based on the results of the cycle, exergy, and Cost analyses. Through a numerical study, it turns out that the proposed systems approach enables one to conduct the thermoeconomic analysis and optimization efficiently.Copyright © 2005 by ASME

  • structural optimization of an energy supply system from economic viewpoint
    Jsme International Journal Series B-fluids and Thermal Engineering, 2004
    Co-Authors: Satoshi Gamou, Ryohei Yokoyama, Koichi Ito, Shu Yoshida
    Abstract:

    An optimal planning method of system structure is proposed to determine kinds, numbers and capacities of equipment for an energy supply system installed in commercial and public buildings from economic viewpoint. In this method, they are determined together with maximum contract demands of utilities such as electricity and natural gas so as to minimize the Annual Total Cost in consideration of system's Annual operational strategies corresponding to seasonal and hourly energy demand requirements. A numerical study is carried out for an office building with Total floor area of 15 000 m 2 . Through the study, the following are clarified: (a) the optimal system structure for the office building; (b) the economic effects of the optimal system compared to other typical energy supply systems; (c) the influence on the optimal system structure of the future efficiency improvement and initial capital Cost reduction of equipment.

  • effect of inlet air cooling by ice storage on unit sizing of a gas turbine cogeneration plant
    Journal of Engineering for Gas Turbines and Power-transactions of The Asme, 2004
    Co-Authors: Ryohei Yokoyama, Koichi Ito
    Abstract:

    In the commercial sector, heat and power demands peak in the summer daytime because of high space cooling demands, and cogeneration plants are required to produce maximum heat and power to meet their demands. However, gas turbine cogeneration plants have the disadvantage of decreases in maximum power output in the summer daytime, which reduces the availability of gas turbines. One of the ways to avoid the aforementioned disadvantage is to cool inlet air and augment maximum power output. In addition, one of the ways for inlet air cooling is to make ice by driving electric compression refrigerators using off-peak power generated during the nighttime, store it in ice banks, and use its heat for inlet air cooling during the on-peak period. The objective of this paper is to investigate the effect of inlet air cooling by ice storage on the unit sizing and Cost of a gas turbine cogeneration plant. An optimal unit sizing method based on the mixed-integer linear programming is used to rationally determine equipment capacities and operational strategies of the plant. A numerical study is conducted, in which the gas turbine cogeneration plants with and without inlet air cooled by ice storage are compared with each other, and the effect of inlet air cooling on the equipment capacities as well as the Annual Total Cost and its items is clarified.

  • optimal unit sizing of cogeneration systems in consideration of uncertain energy demands as continuous random variables
    Energy Conversion and Management, 2002
    Co-Authors: Satoshi Gamou, Ryohei Yokoyama, Koichi Ito
    Abstract:

    Abstract An optimal unit sizing method for cogeneration systems is proposed using energy demands as continuous random variables. In this method, design variables such as equipment capacities and maximum contract utility demands are determined together with the systems' operational strategies so as to minimize an expected value of the Annual Total Cost subject to the satisfaction of all the possible energy demands. In evaluating the expected value, decision variables and the objective function are considered as piece-wise linear functions of energy demands by applying a sensitivity analysis in linear programming and an enumeration method in mixed-integer programming. This optimization problem is formulated and solved based on a hierarchical optimization algorithm. A numerical study is carried out on a fuel cell cogeneration system installed in an office building. Through the study, the influence of uncertainties in energy demands on a system's economics and optimal equipment capacities are clarified.

  • effect of inlet air cooling by ice storage on unit sizing of a gas turbine cogeneration plant
    ASME Turbo Expo 2002: Power for Land Sea and Air, 2002
    Co-Authors: Ryohei Yokoyama, Koichi Ito
    Abstract:

    In the commercial sector, heat and power demands peak in the summer daytime because of high space cooling demands, and cogeneration plants are required to produce maximum heat and power to meet their demands. However, gas turbine cogeneration plants have the disadvantage of decreases in maximum power output in the summer daytime, which reduces the availability of gas turbines. One of the ways to avoid the aforementioned disadvantage is to cool inlet air and augment maximum power output. In addition, one of the ways for inlet air cooling is to make ice by driving electric compression refrigerators using off-peak power generated during the nighttime, store it in ice banks, and use its heat for inlet air cooling during the on-peak period. The objective of this paper is to investigate the effect of inlet air cooling by ice storage on the unit sizing and Cost of a gas turbine cogeneration plant. An optimal unit sizing method based on the mixed-integer linear programming is used to rationally determine equipment capacities and operational strategies of the plant. A numerical study is conducted, in which the gas turbine cogeneration plants with and without inlet air cooled by ice storage are compared with each other, and the effect of inlet air cooling on the equipment capacities as well as the Annual Total Cost and its items is clarified.Copyright © 2002 by ASME

Satoshi Gamou - One of the best experts on this subject based on the ideXlab platform.

  • structural optimization of an energy supply system from economic viewpoint
    Jsme International Journal Series B-fluids and Thermal Engineering, 2004
    Co-Authors: Satoshi Gamou, Ryohei Yokoyama, Koichi Ito, Shu Yoshida
    Abstract:

    An optimal planning method of system structure is proposed to determine kinds, numbers and capacities of equipment for an energy supply system installed in commercial and public buildings from economic viewpoint. In this method, they are determined together with maximum contract demands of utilities such as electricity and natural gas so as to minimize the Annual Total Cost in consideration of system's Annual operational strategies corresponding to seasonal and hourly energy demand requirements. A numerical study is carried out for an office building with Total floor area of 15 000 m 2 . Through the study, the following are clarified: (a) the optimal system structure for the office building; (b) the economic effects of the optimal system compared to other typical energy supply systems; (c) the influence on the optimal system structure of the future efficiency improvement and initial capital Cost reduction of equipment.

  • optimal unit sizing of cogeneration systems in consideration of uncertain energy demands as continuous random variables
    Energy Conversion and Management, 2002
    Co-Authors: Satoshi Gamou, Ryohei Yokoyama, Koichi Ito
    Abstract:

    Abstract An optimal unit sizing method for cogeneration systems is proposed using energy demands as continuous random variables. In this method, design variables such as equipment capacities and maximum contract utility demands are determined together with the systems' operational strategies so as to minimize an expected value of the Annual Total Cost subject to the satisfaction of all the possible energy demands. In evaluating the expected value, decision variables and the objective function are considered as piece-wise linear functions of energy demands by applying a sensitivity analysis in linear programming and an enumeration method in mixed-integer programming. This optimization problem is formulated and solved based on a hierarchical optimization algorithm. A numerical study is carried out on a fuel cell cogeneration system installed in an office building. Through the study, the influence of uncertainties in energy demands on a system's economics and optimal equipment capacities are clarified.

  • optimal unit sizing of cogeneration systems under the toleration for shortage of energy supply
    International Journal of Energy Research, 2000
    Co-Authors: Satoshi Gamou, Ryohei Yokoyama, Koichi Ito
    Abstract:

    The paper investigates the influence of tolerating the shortage of energy supplies on the economy of cogeneration systems in consideration of energy demands as random variables. To make a reasonable investigation into the influence, an optimal unit sizing method proposed by the authors is adopted after it is extended to this case so that it enables probability distributions of energy demands to be considered. In the method, equipment capacities and maximum contract demands of utilities such as electricity and natural gas are determined so as to minimize the expected value of the Annual Total Cost in consideration of operational strategies for all the estimated energy demands under the toleration for the shortage of energy supplies. Numerical studies are carried out on cogeneration systems installed in a hotel or an office building with changing shortage rates of energy supplies as parameters. Through the studies, it is found that the expected systems' economy is improved even if the shortage rates of energy supplies are very small, and that the improvement for the office building is larger than that for the hotel. Copyright © 2000 John Wiley & Sons, Ltd.

  • optimal unit sizing of fuel cell cogeneration systems in consideration of performance degradation
    International Journal of Energy Research, 1998
    Co-Authors: Koichi Ito, Satoshi Gamou, Ryohei Yokoyama
    Abstract:

    The influence of the life of a cell stack due to performance degradation on a system's economy is investigated in unit sizing of fuel cell cogeneration systems. An optimal unit sizing method proposed by the authors is extended to this case so that it enables the life and performance degradation of the cell stack to be considered. In the method, equipment capacities and maximum contract demands of utilities such as electricity and natural gas are determined so as to minimize the Annual Total Cost leveled for a whole planning period based on the Annualized Costs method, in consideration of operational strategies which change with performance degradation of the cell stack. Numerical studies are carried out for normally and highly pressurized phosphoric acid fuel cell cogeneration systems installed in two urban areas. Through the studies, it is found that the life of the cell stack greatly influences system' economics and equipment capacities. © 1998 John Wiley & Sons, Ltd.

Shengwei Wang - One of the best experts on this subject based on the ideXlab platform.

  • robust optimal design of chilled water systems in buildings with quantified uncertainty and reliability for minimized life cycle Cost
    Energy and Buildings, 2016
    Co-Authors: Qi Cheng, Shengwei Wang
    Abstract:

    Abstract Conventional design of chilled water systems is typically based on the peak cooling loads of buildings, while the cooling load reaches its peak level for only a small proportion of time in a year. This results in that design flow of chilled water system could be significantly oversized in actual operation and it thus causes significant energy wastes. In this paper, a robust optimal design based on minimized life-cycle Cost is proposed to optimize the design of chilled water pump systems while concerning the uncertainties of design inputs and models as well as the component reliability in operation. Monte Carlo simulation is used to generate the cooling load distribution and hydraulic resistance distribution by quantifying the uncertainties. Markov method is used to obtain the probability distribution of the system state. Under different control methods, this proposed design method minimizes the Annual Total Cost. A case study on a building in Hong Kong is conducted to demonstrate the design process and validate the robust optimal design method. Results show that the system could operate at a relatively high efficiency and the minimum Total life-cycle Cost could be achieved.

  • robust optimal design of building cooling systems considering cooling load uncertainty and equipment reliability
    Applied Energy, 2015
    Co-Authors: Wenjie Gang, Shengwei Wang, Fu Xiao
    Abstract:

    Appropriate design provides the cooling system to achieve good performance with low energy consumption and Cost. Conventional design method in heating, ventilation and air-conditioning (HVAC) field usually selects the cooling system based on certain cooling load and experiences. The performance of the selected cooling system may deviate from the expectations due to cooling load uncertainty. This paper proposes a novel design method to obtain the robust optimal cooling systems for buildings by quantifying the uncertainty in cooling load calculation and equipment reliability in operation comprehensively. By quantifying the cooling load uncertainty with Monte Carlo method and chiller reliability using Markov method, the robust optimal cooling system is obtained with minimum Annual Total Cost. By applying the new method in the design of the cooling system for a building, its function and performance as well as potential benefits are demonstrated and evaluated. Results show that the proposed method can obtain the optimal cooling systems with low Cost and high robustness and provides a promising means for designers to make their best design decisions based on quantitative assessment according to their priority.