The Experts below are selected from a list of 237 Experts worldwide ranked by ideXlab platform
Jiangfeng Wang - One of the best experts on this subject based on the ideXlab platform.
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Thermodynamic and economic analysis and multi-objective optimization of a novel transcritical CO2 Rankine cycle with an ejector driven by low grade Heat Source
Energy, 2018Co-Authors: Jiangfeng Wang, Kehan Zhou, Pan ZhaoAbstract:Abstract Transcritical CO2 Rankine cycle (T-CO2) is a promising technology for the utilization of low temperature Heat Source. The low critical temperature of CO2 (about 31 °C) leads to a restriction in the practical application of the cycle, since CO2 could hardly be condensed into liquid using higher temperature Heat sink under the environment conditions. In this paper, a novel transcritical CO2 Rankine cycle with an ejector is proposed to solve the condensation problem of CO2 under the higher temperature Heat sink. By establishing the mathematical model, a parametric analysis is carried out to examine the effects of five key parameters on thermodynamic and economic performances of the system. A multi-objective optimization is also conducted to obtain the optimum performance of cycle. The results indicate that increasing turbine inlet temperature and ejector back pressure could increase the exergy efficiency. In addition, lower investment cost of the system could be achieved by increasing the turbine back pressure and the valve expansion pressure. Furthermore, according to the Pareto frontier solution of multi-objective optimization, the exergy efficiency could reach a maximum of 19.33% and the investment cost of the system could reach a minimum of 657.9 × 103 USD.
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Three-dimensional performance analysis of a radial-inflow turbine for an organic Rankine cycle driven by low grade Heat Source
Energy Conversion and Management, 2018Co-Authors: Jiangfeng Wang, Hongyang WangAbstract:Abstract Turbine is one of the key components in organic Rankine cycle, and its aerodynamic performance and geometric dimension affect the performance of the system directly. This paper presents the one-dimensional design and three-dimensional CFD analysis for an ORC radial-inflow turbine based on the parameter optimization of the system under low grade Heat Source conditions. Real Gas Property (RGP) file is encoded by using the NIST REFPROP database to guarantee the prediction accuracy of the working fluid properties. The results comparison between the one-dimensional design and the three-dimensional CFD simulation is carried out. What’s more, the addition of splitter blade to the rotor passage is considered to optimize the ORC radial-inflow turbine. It is concluded that the three-dimension CFD results are in good agreement with the one-dimensional analysis. And the addition of splitter blade is benefit to improve the performance of the ORC radial-inflow turbine.
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Comprehensive analysis and optimization of Kalina-Flash cycles for Low-Grade Heat Source
Applied Thermal Engineering, 2018Co-Authors: Jiangfeng Wang, Liangqi ChenAbstract:Abstract In this paper, two configurations of Kalina-Flash cycles (KFC) are proposed to recover Low-Grade Heat Source. The thermodynamic and economic models of Kalina-Flash cycles are established. A numerical simulation is conducted, and a parametric analysis is performed to examine the effect of five key parameters, including separator temperature, separator pressure, ammonia mass fraction of ammonia-water basic solution, flash pressure and pinch-point temperature difference, on the thermodynamic and economic performances of Kalina-Flash cycles. Furthermore, a single-objective optimization and a multi-objective optimization are carried out by genetic algorithm and Non-dominated sorting genetic algorithm-II to obtain the optimum thermodynamic and economic performances. The single-objective optimization results show that the Kalina-Flash cycles can achieve higher exergy efficiency and lower specific investment cost than Kalina cycle does. The multi-objective optimization results of Kalina-Flash cycles present the Pareto frontier solutions, which is a series of optimum solutions for exergy efficiency and total capital investment. The Pareto frontier solutions indicate that Kalina-Flash cycles are superior to Kalina cycle in the aspect of thermodynamic and economic performances.
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Assessment of off-design performance of a Kalina cycle driven by Low-Grade Heat Source
Energy, 2017Co-Authors: Jianyong Wang, Jiangfeng Wang, Pan ZhaoAbstract:Abstract Kalina cycle is a promising power cycle to utilize or recover the Heat of Low-Grade Heat Sources. Most of previous works focused on the thermodynamic and thermoeconomic analysis or optimization for the cycle. In this paper, an off-design mathematical model for Kalina cycle is established to examine the off-design performance of the cycle with the variation of Heat Source mass flow rate, Heat Source temperature and cooling water temperature. A modified sliding pressure regulation method, which regulates the turbine inlet pressure to keep the temperature difference between Heat Source temperature and turbine inlet temperature constant, is applied to control the cycle when off-design conditions occur. The results show that the modified sliding pressure regulation method keeps Kalina cycle with a good off-design performance. With the increase of Heat Source mass flow rate or Heat Source temperate, both of the net power output and thermal efficiency increase. With the increase of cooling water temperature, both of the net power output and thermal efficiency decrease. In addition, the turbine efficiency almost keeps the designed value under the off-design conditions.
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Thermodynamic analysis of a Kalina-based combined cooling and power cycle driven by Low-Grade Heat Source
Applied Thermal Engineering, 2017Co-Authors: Jiangfeng Wang, Hongyang Wang, Pan ZhaoAbstract:Abstract This paper investigates a Kalina-based combined cooling and power (CCP) cycle driven by Low-Grade Heat Source. The proposed cycle consists of a Kalina cycle and an absorption refrigeration cycle. By establishing the mathematical model, numerical simulation is conducted and parametric analysis is performed to examine the effects of five key parameters on the thermodynamic performances of Kalina-based CCP cycle. A performance optimization is conducted by genetic algorithm to obtain the optimum exergy efficiency. According to parametric analysis, an optimum expander inlet pressure can be achieved; exergy efficiency increases with expander inlet pressure and concentration of ammonia-water basic solution, but exergy efficiency decreases when terminal temperature difference of high-temperature recuperator and low-temperature recuperator increases. Refrigeration exergy increases with expander inlet pressure and decreases as expander inlet temperature and concentration of ammonia-water basic solution rise. However, the refrigeration exergy keeps constant as the terminal temperature difference of high-temperature recuperator and low-temperature recuperator vary. Furthermore, the optimized Kalina-based CCP cycle is compared with a separate generation system which is also optimized. The optimization results show that the exergy efficiency and net power output of Kalina-based CCP are higher than those of separate generation system.
Jinghuang Zou - One of the best experts on this subject based on the ideXlab platform.
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Operation and performance of a low temperature organic Rankine cycle
Applied Thermal Engineering, 2015Co-Authors: Zheng Miao, Xufei Yang, Jinliang Xu, Jinghuang ZouAbstract:The test and analysis of an Organic Rankine Cycle (ORC) with R123 as the working fluid were presented in this paper. A scroll expander was integrated in the system to generate work. The expander was connected with an AC dynamometer unit, which was used to control and measure the expander shaft torque and rotating speed. The conductive oil simulated the low grade Heat Source. Operation characteristics were compared between the Heat Source temperatures of 140°C and 160°C. The experiments were conducted by adjusting two independent parameters: the pumping frequency of the R123 pump and the shaft torque of the expander. The former parameter was directly related to the R123 mass flow rate and the later to the external load. The optimum system performance can be determined by these two parameters. The maximum measured shaft power and thermal efficiency were 2.35 kW and 6.39% at the Heat Source temperature of 140°C, but they were 3.25 kW and 5.12% at the Heat Source temperature of 160°C. This study identified that the measured shaft power was about 15-20% lower than the enthalpy determined values, and the pumping power of the organic fluid was 2-4 times higher than the enthalpy determined values. The enthalpy determined values were based on the local pressure and temperature sensor measurements.
L. Garousi Farshi - One of the best experts on this subject based on the ideXlab platform.
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Thermo-economic analysis of combined different ORCs geothermal power plants and LNG cold energy
Geothermics, 2017Co-Authors: A. H. Mosaffa, N. Hasani Mokarram, L. Garousi FarshiAbstract:Thermo-economic analysis is applied to four combined liquefied natural gas (LNG) cold energy and (1) simple, (2) with internal Heat exchanger, (3) regenerative and (4) dual-fluid ORCs. These power plants use geothermal fluid energy as Low-Grade Heat Source and cold energy of LNG as thermal sink. Also, after vaporization in the organic fluid condenser, natural gas expands in a turbine to generate power. The effects of operating parameters on energy and exergy efficiencies as well as total annual cost rate are studied for the proposed systems. The operating parameters considered include inlet pressure of the organic fluid and natural gas turbines, condensing temperature of organic fluid, minimum temperature difference in evaporator, inlet temperature and mass flow rate of geothermal fluid. Moreover, optimal values of operating parameters of the system are evaluated to maximize the energy and exergy efficiencies and minimize the total product unit cost. The results show that the highest energy and exergy efficiencies are obtained for regenerative system and for the system with internal Heat exchanger, respectively, while the simple system has the lowest total product cost. Furthermore, the maximum net power output is obtained using dual-fluid system at the same operating condition. Also, the higher and lower total cost rate in optimum performance condition belong to dual-fluid and regenerative systems, respectively.
Yang Chen - One of the best experts on this subject based on the ideXlab platform.
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Second Law Analysis of a Carbon Dioxide Transcritical Power System in Low-Grade Heat Source Recovery
2011Co-Authors: Yang Chen, Per Lundqvist, Almaz Bitew WorkieAbstract:Employing Carbon dioxide as a working media in power cycles for Low-Grade Heat Source utilization has attracted more and more attentions. However, compared to other well-known cycles that employed ...
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The Co2 Transcritical Power Cycle For Low Grade Heat Recovery-Discussion On Temperature Profiles In System Heat Exchangers
ASME 2011 Power Conference Volume 1, 2011Co-Authors: Yang Chen, Per LundqvistAbstract:Carbon dioxide transcritical power cycle has many advantages in Low-Grade Heat Source recovery compared to conventional systems with other working fluids. This is mainly due to the supercritical CO ...
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Low-Grade Heat Source Utilization by Carbon Dioxide Transcritical Power Cycle
ASME JSME 2007 Thermal Engineering Heat Transfer Summer Conference Volume 1, 2007Co-Authors: Yang Chen, Wimolsiri Pridasawas, Per LundqvistAbstract:One way to reduce the fossil fuel consumption and mitigate environmental impact is to utilize Low-Grade Heat Sources for power production. In this paper, a transcritical carbon dioxide power cycle ...
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Carbon dioxide cooling and power combined cycle for mobile applications
2006Co-Authors: Yang Chen, Per Gunnar LundqvistAbstract:The interest in utilizing the energy in low‐grade Heat Sources and waste Heat is increasing. There is an abundance of such Heat Sources, but their utilization today is insufficient, mainly due to the limitations of the conventional power cycles in such applications, such as low efficiency, bulky size or moisture at the expansion outlet (e.g. problems for turbine blades). Carbon dioxide (CO2) has been widely investigated for use as a working fluid in refrigeration cycles, because it has no ozonedepleting potential (ODP) and low global warming potential (GWP). It is also inexpensive, non‐explosive, non‐flammable and abundant in nature. At the same time, CO2 has advantages in use as a working fluid in low‐grade Heat reSource recovery and energy conversion from waste Heat, mainly because it can create a better matching to the Heat Source temperature profile in the supercritical region to reduce the irreversibility during the Heating process. Nevertheless, the research in such applications is very limited. This study investigates the potential of using carbon dioxide as a working fluid in power cycles for low‐grade Heat Source/waste Heat recovery. At the beginning of this study, basic CO2 power cycles, namely carbon dioxide transcritical power cycle, carbon dioxide Brayton cycle and carbon dioxide cooling and power combined cycle were simulated and studied to see their potential in different applications (e.g. low‐grade Heat Source applications, automobile applications and Heat and power cogeneration applications). For the applications in automobile industries, low pressure drop on the engine’s exhaust gas side is crucial to not reducing the engine’s performance. Therefore, a Heat exchanger with low‐pressure drop on the secondary side (i.e. the gas side) was also designed, simulated and tested with water and engine exhaust gases at the early stage of the study (Appendix 2). The study subsequently focused mainly on carbon dioxide transcritical power cycle, which has a wide range of applications. The performance of the carbon dioxide transcritical power cycle has been simulated and compared with the other most commonly employed power cycles in lowgrade Heat Source utilizations, i.e. the Organic Rankin Cycle (ORC). Furthermore, the annual performance of the carbon dioxide transcritical power cycle in utilizing the low‐grade Heat Source (i.e. solar) has also been simulated and analyzed with dynamic simulation in this work. Last but not least, the matching of the temperature profiles in the Heat exchangers for CO2 and its influence on the cycle performance have also been discussed. Second law thermodynamic analyses of the carbon dioxide transcritical power systems have been completed. The simulation models have been mainly developed in the software known as Engineering Equation Solver (EES)1 for both cycle analyses and computer‐aided Heat exchanger designs. The model has also been connected to TRNSYS for dynamic system annual performance simulations. In addition, Refprop 7.02 is used for calculating the working fluid properties, and the CFD tool (COMSOL) 3 has been employed to investigate the particular phenomena influencing the Heat exchanger performance.
Per Lundqvist - One of the best experts on this subject based on the ideXlab platform.
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Second Law Analysis of a Carbon Dioxide Transcritical Power System in Low-Grade Heat Source Recovery
2011Co-Authors: Yang Chen, Per Lundqvist, Almaz Bitew WorkieAbstract:Employing Carbon dioxide as a working media in power cycles for Low-Grade Heat Source utilization has attracted more and more attentions. However, compared to other well-known cycles that employed ...
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The Co2 Transcritical Power Cycle For Low Grade Heat Recovery-Discussion On Temperature Profiles In System Heat Exchangers
ASME 2011 Power Conference Volume 1, 2011Co-Authors: Yang Chen, Per LundqvistAbstract:Carbon dioxide transcritical power cycle has many advantages in Low-Grade Heat Source recovery compared to conventional systems with other working fluids. This is mainly due to the supercritical CO ...
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Low-Grade Heat Source Utilization by Carbon Dioxide Transcritical Power Cycle
ASME JSME 2007 Thermal Engineering Heat Transfer Summer Conference Volume 1, 2007Co-Authors: Yang Chen, Wimolsiri Pridasawas, Per LundqvistAbstract:One way to reduce the fossil fuel consumption and mitigate environmental impact is to utilize Low-Grade Heat Sources for power production. In this paper, a transcritical carbon dioxide power cycle ...
