دکتر شیوا گرجیان

Due to the increase in freshwater demand and climatic threats such as the drought phenomenon, it is necessary to implement efficient methods in water and wastewater treatment. Therefore, it is very vital to provide solutions in the agricultural sector and related industries as the largest water consumer in the world. In this regard, the desalination of greenhouse effluent and its reuse by relying on different energy sources can be considered a big step towards the sustainable development of the agricultural industry. Shell and tube exchangers are widely used in various industries. This research is focused on design, simulation, and optimization of four exchangers connected together in the wastewater treatment network of a greenhouse with an area of 2000 m2 located in Tehran using HYSYS and EDR software. One of the advantages of this method compared to reverse osmosis is that it reduces pollution of the environment and water sources. Among the innovations of this research is the use of thermal methods in the agricultural industry. The obtained result shows that the first converter with a square arrangement includes 37 tubes with a length of 1650 mm, the second converter with a square arrangement includes 52 tubes with a length of 1850 mm, the third converter with a triangular arrangement includes 24 tubes with a length of 1700 mm, and the fourth with a square arrangement consisting of 24 tubes with a length of 800 mm. The network is optimal, and 160 L/h of freshwater are delivered to the greenhouse.

Concentrators have many functions, one of which is their use in the evaporation of liquids. Since a high level of heat is present in concentrator absorbers, it is possible to develop a heat exchanger system that enables the vaporization of salt water. One of the main components of these systems is the heat absorber, which is located at the focal point. In this study, an attempt was made to investigate two geometries of annular and hollow absorbers using the computational fluid dynamics (CFD) method. For this purpose, the working fluid was defined based on the properties of seawater in the Fluent Ansys software, and the creation of the geometry and thermal analysis was considered based on the initial and boundary conditions of the system. The results of the validation of the grid quality showed that the use of a tetrahedral grid with square grid order is suitable for the cylindrical geometry. Due to the dimensional symmetry of the geometry of the ring converter, the use of the simplest grid method leads to a high accuracy of the solver. The thermal analysis of the absorber has shown that with the cavity geometry, the heat distribution at the bottom of the geometry is greater than at the top. The results of the Nusselt number change analysis showed the concentration of thermal stress in the area of the liquid outlet. This stress concentration leads to a shift of the evaporation process from the inside of the chamber to the transfer tubes.

Iran is one of the countries with a radiation potential that is very suitable for the construction of solar carports. Considering the high initial cost of constructing these parking lots, the importance of their feasibility and optimal design is very high. In the present study, the design and simulation of a solar carport connected to the power grid that was implemented at the Faculty of Agriculture of Tarbiat Modares University (TMU) in Tehran was carried out. For this purpose, the photovoltaic system was calculated in PVsyst software considering the geographical location and weather conditions of Tehran. In this case, the optimal side angle for installing the photovoltaic modules on the parking lot was set at 35 degrees to maximize the annual electricity production. Then, in determining the type and model of the photovoltaic modules and the solar inverter, their optimal electrical arrangement was designed. In addition, the losses of the various parts of the system were calculated, including the losses caused by shading, temperature rise, connecting wires, and so on; besides, the optimal spacing and arrangement of the modules were presented. Based on the final results of the simulation, the amount of electricity generated by the parking lot was 48.2 MWh/year; the annual power factor was 0.791; the reduction rate of CO2 production was 499.89 tons in a total of 30 years, and the sensitivity analysis and lower return on investment were calculated from 5 years onwards. The results of this study showed that the implementation of the project at the investigated site was economically justified in addition to the benefit of providing renewable electricity.