Performance evaluation and economic assessment of a gas power plant with solar and desalination integrated systems

In this study, a new configuration of a cogeneration system of electricity and freshwater in integration with solar collector has been thoroughly investigated. A gas power plant is modeled thermodynamically. The results of this modeling are compared with the actual data of a power plant to verify the simulation. Subsequently, by placing multi-effect desalination with thermal vapor compression and solar collectors, the functions including energy and exergy efficiencies and carbon dioxide emissions of the power plant have been studied. By applying the desalinating cycle and solar collectors, the energy efficiency of this power plant is increased from 35% to 46% and the exergy efficiency from 37% to 48%. This configuration of the cogeneration system with linear solar collectors produces 16.479 m3 of fresh water per day while reducing the CO2 emissions by 37,216 tons/d.http://www.deswater.comam2020Mechanical and Aeronautical Engineerin

Sensitivity analysis of combined cycle parameters on exergy, economic, and environmental of a power plant

In this paper, a typical combined cycle power generation unit in Iran is simulated by a mathematical method in order to perform sensitivity analysis on environmental emission and electricity price. The results of this study demonstrate that the efficiency of the power plant depends on both gas turbine design parameters such as gas turbine inlet temperature, compressor pressure ratio and steam cycle design parameters such as HRSG pinch point temperature, condenser pressure. The results demonstrate that an increase in TIT and compressor pressure ratio have a significant effect on exergy efficiency and destruction.http://link.springer.com/journal/109732020-05-28hj2020Mechanical and Aeronautical Engineerin

Experimental Investigation of Flow Control over an Ahmed Body using DBD Plasma Actuator

Ahmed body is a standard configuration of road vehicles and most of the studies of automobile aerodynamics are performed based on it. In this paper, the plasma actuator was used as an active flow control method to control the flow around the rear part of the Ahmed body with the rear slant angle of 25°. Experiments were carried out in a wind tunnel at two different velocities of U=10m/s and U=20m/s using steady and unsteady excitations. The hot-wire anemometer was used to measure the vortex shedding frequency at the downstream of the body. Pressure distribution was measured using 52 sensors and total drag force was extracted with a load cell. Furthermore, smoke flow visualization was employed to investigate the flow pattern around the body. The results showed that the plasma actuator was more effective on the pressure distribution and total drag force at the velocity of U=10m/s. In fact, by applying steady and unsteady excitations there was 7.3% and 5% drag reduction; respectively. While at the velocity of U=20m/s; the actuator had no significant effect on pressure distribution and total drag. As a remarkable result, the plasma actuator, especially in the steady actuation, has demonstrated its effectiveness on dispersing the longitudinal vortices and suppressing the separated flow on the rear slant at low velocities

Modeling and predicting of the flash point of chemical compounds

Flash point is one of the most important flammability characteristics of chemical compounds. In the present study, we developed a neural network model for accurate prediction of the flash point of chemical compounds, using the number of hydrogen and carbon atoms, critical temperature, normal boiling point, acentric factor and enthalpy of formation as model inputs. Using a robust strategy to efficiently assign neural network parameters and evaluate the authentic performance of the neural networks, we could achieve an accurate model which yielded average absolute relative errors of 0. 97, 0. 96, 0.99 and 1.0% and correlation coefficients of 0.9984, 0.9985, 0.9981 and 0.9979 for the overall, training, validation and test sets, respectively. These results are among the most accurate ever reported ones, to date.in this article method for selection the best learning algorithm and transfer function are clearly presented and relative error for these parameters are represented in detail

4E Transient Analysis of a Solar-Hybrid Gas-Turbine Cycle Equipped with Heliostat and MED

The current study investigates a cogeneration cycle of power and freshwater integrated with a solar system. The solar system is of the heliostat type, which is considered to preheat the inlet air in the combustion chamber of a 25-MW gas turbine. The waste heat of the turbine output stream is used to produce freshwater. Parameters such as the ambient temperature and solar irradiance significantly affect the system’s performance; hence, all analyses, including those pertaining to energy, exergy, economics, and environment, were conducted transiently, with a one-hour time step throughout the year so that the impacts of these effective parameters could be examined. Besides the analysis assuming a constant mass flow rate for the air entering the compressor, the calculations were repeated with the assumption of a constant volumetric flow rate to evaluate the cycle in the same conditions as those of natural gas power plants. Given the constant volumetric flow rate, for every 10-degree increase in temperature, the compressor power consumption decreased by approximately 2%. Moreover, a sensitivity analysis of the cycle performance in terms of ambient temperature was performed, and the corresponding results are presented. Finally, some correlations are presented to estimate variations in compressor power consumption and net turbine power due to temperature variations. The results demonstrate that in Bushehr, Iran, every one-degree increase in ambient temperature leads to an approximately 0.67 percentage decrease in net-generated power. In the end, the performance of the cycle was investigated under climatic conditions and solar irradiation intensities in several cities in Iran and some cities in different countries in which heliostat power plants have already been established. The results obtained in these cities were compared; it was concluded that the lowest annual cost of electricity generation is related to Isfahan in Iran, which reduces the cost of electricity generation by more than 20% (2.32 Cents/kWh) compared to the base cycle.</p

Time-Transient Optimization of Electricity and Fresh Water Cogeneration Cycle Using Gas Fuel and Solar Energy

In this study, a cogeneration cycle in a time-transient state is investigated and optimized. A quasi-equilibrium state is assumed because of the small time increments. Air temperature and solar power are calculated hourly. The cycle is considered in terms of energy, exergy, and economic and environmental analyses. Increasing the net present value (the difference between the present value of the cash inflows and outflows over a period of time) and reducing exergy destruction are selected as two optimization objective functions. The net present value is calculated for the period of 20 years of operation according to the operation parameters. The optimization variables are selected in such a way that one important variable is selected from each system. To optimize the cycle, the particle swarm optimization method is used. The number of particles used in this method is calculated using the trial-and-error method. This cycle is optimized using 13 particles and 42 iterations. After optimization, the energy efficiency increased by 0.5%, the exergy efficiency increased by 0.25%, and the exergy destruction decreased by 1% compared to the cycle with existing parameters

Time-Transient Optimization of Electricity and Fresh Water Cogeneration Cycle Using Gas Fuel and Solar Energy

In this study, a cogeneration cycle in a time-transient state is investigated and optimized. A quasi-equilibrium state is assumed because of the small time increments. Air temperature and solar power are calculated hourly. The cycle is considered in terms of energy, exergy, and economic and environmental analyses. Increasing the net present value (the difference between the present value of the cash inflows and outflows over a period of time) and reducing exergy destruction are selected as two optimization objective functions. The net present value is calculated for the period of 20 years of operation according to the operation parameters. The optimization variables are selected in such a way that one important variable is selected from each system. To optimize the cycle, the particle swarm optimization method is used. The number of particles used in this method is calculated using the trial-and-error method. This cycle is optimized using 13 particles and 42 iterations. After optimization, the energy efficiency increased by 0.5%, the exergy efficiency increased by 0.25%, and the exergy destruction decreased by 1% compared to the cycle with existing parameters

A New Thermal Conductivity Model and Two-Phase Mixed Convection of CuO–Water Nanofluids in a Novel I-Shaped Porous Cavity Heated by Oriented Triangular Hot Block

This paper investigates the cooling performance of nanofluid (NF) mixed convection in a porous I-shaped electronic chip with an internal triangular hot block using Buongiorno&rsquo;s two-phase model. This type of cavity and hot block geometry has not been studied formerly. The NF was assumed to be a mixture of water and CuO nanoparticles (NP) up to 4% of volume concentration. As most published mathematical models for the thermal conductivity of NF give inaccurate predictions, a new predictive correlation for effective thermal conductivity was also developed with a high accuracy compared to the experimental data. The results showed that any increase in the NP volume concentration enhances the average Nusselt number (Nu&macr;) and the normalized entropy generation, and reduces the thermal performance of the cavity in all orientations of the hot block. The maximum enhancement in cooling performance was 17.75% and occurred in the right-oriented hot block in the sand-based porous cavity. Furthermore, adding the NP to the base fluid leads to a more capable cooling system and enhances the irreversibility of the process