Gholamreza Ahmadi

Bio: Gholamreza Ahmadi is an academic researcher from Islamic Azad University. The author has contributed to research in topics: Exergy & Steam-electric power station. The author has an hindex of 13, co-authored 22 publications receiving 937 citations. Previous affiliations of Gholamreza Ahmadi include Islamic Azad University, Isfahan.

Energy and exergy analysis of Montazeri Steam Power Plant in Iran

Abstract: This paper aims at investigating steam cycle of Shahid Montazeri Power Plant of Isfahan with individual unit capacity of 200 MW. Using mass, energy, and exergy balance equations, all cycle equipment have been analyzed individually and energy efficiency, exergy efficiency, and irreversibility has been calculated for each of them as required. EES (Engineering Equation Solver) software is used for performing analyses. Values and ratios regarding heat drop and exergy loss have been presented for each equipment in individual tables. The results from the energy analysis show that 69.8% of the total lost energy in the cycle occurs in the condenser as the main equipment wasting energy, while exergy analysis introduces the boiler as the main equipment wasting exergy where 85.66% of the total exergy entering the cycle is lost.

The effect of velocity and dimension of solid nanoparticles on heat transfer in non-Newtonian nanofluid

Abstract: In this investigation, the behavior of non-Newtonian nanofluid hydrodynamic and heat transfer are simulated. In this study, we numerically simulated a laminar forced non-Newtonian nanofluid flow containing a 0.5 wt% carboxy methyl cellulose (CMC) solutionin water as the base fluid with alumina at volume fractions of 0.5 and 1.5 as the solid nanoparticle. Numerical solution was modelled in Cartesian coordinate system in a two-dimensional microchannel in Reynolds number range of 10≤Re≤1000. The analyzed geometrical space here was a rectangular part of whose upper and bottom walls was influenced by a constant temperature. The effect of volume fraction of the nanoparticles, Reynolds number and non-Newtonian nanofluids was studied. In this research, the changes pressure drop, the Nusselt number, dimensionless temperature and heat transfer coefficient, caused by the motion of non-Newtonian nanofluids are described. The results indicated that the increase of the volume fraction of the solid nanoparticles and a reduction in the diameter of the nanoparticles would improve heat transfer which is more significant in Reynolds number. The results of the introduced parameters in the form of graphs drawing and for different parameters are compared.

Solar parallel feed water heating repowering of a steam power plant: A case study in Iran

Abstract: Currently, the use of renewable energies is put on the agenda of most researchers in the field of energy. On the other hand, in many parts of the world, fossil fuel power plants continue to be the main source of electrical power. Increased efficiency of fossil fuel power plants and the use of solar energy lead to recommendation of merging solar farms with the cycle of these power plants. The statistics indicate that the output of fossil fuel power plants in Iran, which currently supply about 93.9% of electricity of the national network, is experiencing a negative growth. On the other hand, according to government plans, part of the generated electricity should be provided from renewable energy sources in the next few years. In this paper, the use of solar energy for integration with power-plant units of Isfahan is investigated. To do this, preheat project of the feed water is investigated on 7 separate scenarios. The results showed that replacing all high-pressure feed water preheaters with solar farm increases the net energy and exergy efficiencies of the power plant by 18.3% compared to the simple cycle which respectively reaches to 45% and 43.91%. Given the importance of reducing emissions of CO 2 pollutants at power plants, reduction level of gas emissions, as well as some economic aspects of the integration of solar farm with the cycle of this power plant has also been evaluated.