فهرست مطالب

Energy Equipment and Systems - Volume:8 Issue: 3, 2020
  • Volume:8 Issue: 3, 2020
  • تاریخ انتشار: 1399/06/24
  • تعداد عناوین: 5
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  • Ahmadreza Sajadi *, Sasan Talebi Pages 203-215

    In this study, for the first time, the heat transfer and the pressure drop of zinc oxide nanoparticles in alternating elliptical axis (AEA) tube have been investigated experimentally. The zinc oxide nanoparticles were at volumetric concentrations 1% and 2%. The base fluid was heat transfer oil and the experiments were conducted at constant wall temperature. Also, the study was done in Reynolds number range of 400- 1900. The experimental results show that the heat transfer, pressure drop and, the efficiency of AEA tubes are higher than the circular tube. The heat transfer rate and pressure drop increase by flattening the tube and adding nanoparticles. To compare the heat transfer and pressure drop simultaneously, an efficiency parameter is defined. This parameter shows how much increase in heat transfer can be obtained for the pressure drop of a circular tube with the same hydraulic diameter as the AEA tube. Using AEA tube with nanoparticles increases heat transfers by up to threefold, and pressure drop by up to twofold, resulting in an overall twofold increase in the efficiency.

    Keywords: Alternating Elliptical Axis Tube, nanofluid, Heat Transfer, Pressure drop, Efficiency
  • Bagher Shahbazi *, Faramarz Talati, Mohammad Seyyedmahmoodi, Mortaza Yari Pages 217-235
    In this paper, the annual and economic performance of an integrated solar combined cycle (ISCC) with indirect energy storage tanks is investigated. The study includes four scenarios, in which the combined cycle performance was studied exclusively in the first scenario. In the second scenario, the integrated solar combined cycle (ISCC) was examined, and the use of supplementary firing instead of solar energy with the assumption of producing the same power as that by the ISCC scenario was examined for the third scenario. For the fourth scenario, the use of energy storage in the form of indirect tanks with the purpose of energy storage during peak solar direct normal irradiation times and discharge during peak power electricity consumption within the network for such power plants were subjected to investigation. Results show that the contribution of solar energy in the annual produced power by the ISCC scenario is 40 GWh, which is 2.2% of the total. In the case that this amount of power is produced using supplementary firing, there will be about 1.98 tons of increased fuel consumption, and about 18 kton increased in CO2 production. By using the energy storage system, the annual power generation increases by 5 GWh, which will raise the plant's annual revenue by 0.25 M$ if the increment occurs during peak hours.  Moreover, the levelized costs of energy (LCOE) for the four scenarios are 8.99, 8.86, 9.04, and 9.135 cents/kWh, respectively.
    Keywords: Integrated Solar Combined Cycle, Thermal Energy Storage, Economic Analysis, Levelized Cost of Electricity
  • Alireza Jalali *, Naeem Niknafs Pages 237-251
    In this paper, we perform two-dimensional simulations of cross-flow forward osmosis (FO) membrane modules in the presence of draw and feed channel spacers. For this purpose, the equations corresponding to the conservation of mass, momentum, and convection-diffusion for the mass fraction of solute are solved using a commercial finite volume flow solver. We consider six configurations of channel spacers being constructed by the symmetric and asymmetric placement of cavity, submerged, and zigzag arrangements. We will study the effect of the spacers’ geometrical parameters such as diameter and relative distance in these configurations as well as the solute resistivity of the porous support layer on the performance of the FO membrane modules in terms of water flux, external concentration polarization (ECP) factors, and pressure drop per unit length of the membrane. Our results reveal that increasing the solute resistivity of the porous support layer has an adverse effect on the water flux, whereas the impact on the ECP factors is positive. In addition, it turns out that the submerged configurations, where the spacer filaments are not in direct contact with the membrane surface, produce the highest water flux through the membrane; however, they have an adverse effect on the pressure drop along the membrane surface.
    Keywords: Forward osmosis, concentration polarization, Channel Spacer, Computational fluid dynamics
  • Alireza Bozorgi *, Ghader Ghorbaniasl Pages 253-262
    Several studies show that the Low-Frequency Noise (LFN) of wind turbines could have harmful effects on human health even when it is infrasound. In traditional classifications, the LFN of upwind turbines is referred only to steady thickness and steady loading sources, and the effect of vortices is considered negligible. In this study, the LFN of a horizontal axis wind turbine is simulated in wind speeds of 5-25 m/s by using a hybrid approach. The results show that vortices being far from blades have a significant effect on the LFN. It is also observed that the position received maximum LFN is far from the point introduced by the IEC 61400-11 standard for measuring the noise of horizontal axis wind turbines.
    Keywords: Wind Turbine, noise pollution, NREL Phase VI, Mean Flow
  • Nima Bahrami Ziabari, Samane Ghandehariun * Pages 263-273
    The climate change crisis has urged societies to take action for mitigating greenhouse gas emissions. Carbon neutral fuel is one of the proposed solutions to achieve this goal. Carbon neutral fuel is the product of captured CO2 with different methods such as direct air capture, sea water-absorbent, and power plant chimneys, and reformed through reactions with hydrogen under high temperatures and pressures. Methane, Methanol, E-diesel and Dimethyl Ether are some fuels that can be made through these processes. With this renewable fossil fuel, there will be no need for building new infrastructures, and it saves tons of money and mitigates greenhouse gas emissions resulting in higher GDP and life quality in the long term. Since there must be no added CO2 emissions within the whole process of carbon-neutral fuel production, to fulfill carbon neutrality, the hydrogen component should be produced from renewable energy sources like solar, wind or geothermal. This paper presents an economic assessment of the solar-based hydrogen for green methanol production. The results show that the levelized cost of solar-based hydrogen is dramatically higher than fossil-based hydrogen due to lack of investments in the renewable energy section in Iran. With a solar-based hydrogen price of $28.1/kg, green methanol price is evaluated $19159/mt.
    Keywords: Carbon Neutral Fuel, Solar-Based Hydrogen, Greenhouse gases, Renewable Energy, Green Methanol