فهرست مطالب jamshid khorshidi

The present study examined the pool boiling process in a specific geometry by designing, constructing a laboratory complex and Providing Empirical Relations. Investigation of pool boiling process, electrical resistance, critical heat flux, heat transfer coefficient, bubble growth and departure, bubble growth frequency, and nucleation site density by applying heat flux to critical heat flux was carried out on wire mesh element in deionized water at different temperatures. According to the results, increasing the size of mesh and fluid temperature decreased the critical heat flux. In the case of a wire mesh with a constant size of mesh, a fluid with a constant temperature, and the use of heat flux values less than the critical heat flux, the wire temperature increased, but it decreased in the case of increasing the size of mesh, a fluid with a constant temperature and applying critical heat flux values. In the case of a constant size of mesh, the heat transfer coefficient was constant by increasing fluid temperature at values of heat flux less than the critical heat flux, but the heat transfer coefficient was increased with increasing values of heat flux less than the critical heat flux and decreased at critical heat flux values. By increasing 4 times the mesh size in the fluid at 30, 70 and 100°C in the critical heat flux, the heat transfer coefficient decreases by 0.7%. The maximum bubble growth frequency is related to the 0.5 mm wire mesh in 100°C fluid with 0.0763 bubbles per millisecond.

Today, the application of supercritical fluid extraction (SFE) has been the focus of many researchers in various industries due to suitable operating conditions, environmental friendliness (no use of organic solvents) and high efficiency. In this process, a solvent is used for separation in supercritical conditions. Pharmaceutical, oil extraction, and oil and gas industries have conducted extensive research in this field. Electronic and electric devices are constantly being upgraded and updated due to the rapid advancement of science and technology, which creates a number of issues with handling electric and electronic waste (e-waste). The most significant issue is that it is challenging to safely dispose of halogen flame retardants and refractory polymers in e-waste. Supercritical fluid (SCF) techniques provide significant environmental benefits over previous disposal methods like pyrolysis and acid leaching since they pose no dangers for air or water contamination. This study discusses and provides a summary of the basic concepts and appropriate factors of supercritical fluid extraction (SFE). SCF methods were claimed to have recovered precious metals, base metals, and other inorganic minerals from e-waste with a recovery efficiency of further 93%. This study reviews the recent advances in supercritical water (SCW) and supercritical carbon dioxide (SCCO2) extraction technologies for metal recovery from e-wastes. On the other hand, hybrid technologies are significantly improving in this field which could be considered for future studies.

The present study examined the pool boiling process in a specific geometry by designing and constructing a laboratory complex. Investigation of pool boiling process, electrical resistance, critical heat flux, heat transfer coefficient, bubble growth and departure, bubble growth frequency, and nucleation site density by applying heat flux to critical heat flux was carried out on a ring wire in deionized water at different temperatures. According to the results, increasing the number of rings and fluid temperature decreased the critical heat flux. In the case of a ring wire with a constant number of rings, a fluid with a constant temperature, and the use of heat flux values less than the critical heat flux, the wire temperature increased, but it decreased in the case of increasing the number of rings, a fluid with a constant temperature and applying critical heat flux values. In a ring wire with a constant number of rings, the heat transfer coefficient was constant by increasing fluid temperature at values of heat flux less than the critical heat flux, but the heat transfer coefficient decreased at critical heat flux values. The diameters of the produced bubbles were enhanced by increasing heat flux and they separated from the rings when combined. At the beginning of the reddening of the ring wire, a critical heat flux occurred, and considering 110% of the time required for the critical heat flux, the images of the state of the ring wire after the critical heat flux are presented.

One of the critical elements of an adsorption desalination system is the adsorption bed. The system dynamics of a 2-bed single-stage silica gel plus water-based adsorption desalination system were analyzed. A great pattern was expanded using energy conservation and mass connected with the kinetics of the adsorption/desorption process. Computational fluid dynamics (CFD) modeling was used to simulate the adsorption process for a rectangular finned tube-based adsorption bed featured with silica gel adsorbent substance. The adsorbents in the simulation were considered solid volume with defined porosity based on the Darcy equation. The adsorption and desorption modes of  the adsorption bed was simulated. CFD techniques were then applied to study fin thickness and height. The results showed that decreasing the fin thickness increased the water uptake by up to 8% and decreasing the fin height from 30mm to 20mm increased the water uptake by up to 17%. CFD technique was also used to investigate the effects of plate type on the adsorption bed performance. The results showed that the copper plate improved the water uptake up to 9%. The temperature decline of adsorption bed caused by the copper plate was up to 11% more than that of the aluminum plate.

To predict static aeroelastic behavior accurately, two-way fluid and structure interaction (FSI) coupling methods are used to calculate the static deformations and aerodynamic characteristics of the deformed rocket. According to the studies, little research has been done on the weight reduction of space structures. Therefore, due to the stratigicness of the Fin of space structures, the mechanical behavior of the sheets for the construction of the Fin has been experimentally studied using a constrained groove pressing (CGP) method and a comparison has been done between the amounts of deviation caused for a rocket flying in different Mach numbers and different angles of attack, by simulating a two-way FSI Method for WAF and Flat Fins models with two types of material, the CGP 7075-T6 aluminum, and the 4130 steel. Results of constrained groove pressing show that with the increase in the steps of this process, 7075-T6 aluminum with 38% increase of yield strength in fourth transit, 34% increase in tensile strength, 40 percent decrease in elongation, and 62% increase in toughness relative to the prototype, will be produced. The total deviation in WAF Fin is much less than the flat Fin. Also, deviations of Fin made of CGP 7075-T6 aluminum is less than the Fin made of 4130 steel.

Biomass gasification is the process of converting biomass into a combustible gas suitable for use in boilers, engines, and turbines to produce combined cooling, heat, and power. This paper presents a detailed model of a biomass gasification system and designs a multigeneration energy system that uses the biomass gasification process for generating combined cooling, heat, and electricity. Energy and exergy analyses are first applied to evaluate the performance of the designed system. Next, the minimizing total cost rate and the maximizing exergy efficiency of the system are considered as two objective functions and a multiobjective optimization approach based on the differential evolution algorithm and the local unimodal sampling technique is developed to calculate the optimal values of the multigeneration system parameters. A parametric study is then carried out and the Pareto front curve is used to determine the trend of objective functions and assess the performance of the system. Furthermore, sensitivity analysis is employed to evaluate the effects of the design parameters on the objective functions. Simulation results are compared with two other multiobjective optimization algorithms and the effectiveness of the proposed method is verified by using various key performance indicators.

In this study, Exergy analysis and computational fluid dynamics simulation of one of the Iranian Offshore Oil Company boilers at Kharg Island, Dorood 3 (boiler unit) has been carried out simultaneously. A type of fire tube boiler with length of 5980 mm and a diameter of 1360 and three pass tubes is investigated. Desired geometry is drawn using SolidWork software, and the equations are solved using Fluent software. In addition to the momentum equations, the energy and combustion equations were also used to the model. Computational space, including burners, furnaces, hot gas chamber at the end of furnaces, the second pass of the tubes, hot gas chamber from the super heater passes into the third tube pass and finally the stack. Temperature, pressure, velocity and concentration distribution in the boiler has been obtained. The simulation results show good agreement with the experimental data. The results show that the area of maximum mass fraction of NO is made in accordance with the area of maximum temperature in the furnace. NO contaminant is maximum in the flame area. NO contaminant is reduced when the gas temperature in the furnace is reduced;moreover, Exergy analysis is discussed to determine the feasibility of optimize boiler. The results of exergy analysis of operations for the produced heat flux values by fuel gas are obtained and percent error is calculated. The results show that with increasing temperature to °160C fuel, the furnace radiant heat transfer rate increased and the flame temperature and consequently also reduce NO contaminant.

This paper addresses an experimental investigation in the hydrodynamic behavior of a modified slotted sieve tray. Slotted sieve tray (Push valve sieve tray) is a sieve tray that the push valves have been utilized on the tray deck to eliminate liquid gradients and non-uniformity of liquid distribution on the tray. The air-water system was used in an industrial scale experimental rig with an internal diameter of 1.2 m. The dry pressure drop, total pressure drop, weeping and entrainment of the modified slotted sieve tray were measured and compared with the conventional sieve tray. Weeping and pressure drop data for the tray was correlated. Results show the better hydrodynamic behavior of the modified push valve sieve tray than a conventional sieve tray. This modification can be an effective and inexpensive way to debottleneck sieve tray columns, because it has good characteristic of sieve tray and eliminate the disadvantage of sieve tray by increasing the operating window of the tray.

In the present study, experimental investigations about the hydrodynamics of the conical cap tray (ConCap tray) have been carried out. The ConCap tray is an innovative and novel type of cap trays. The effect of the different weir height (2.5, 5 and 7 cm) on the weeping, entrainment and the total pressure drop for the ConCap tray was measured, compared and correlated. The hydraulic experiments were carried out in an industrial scale simulator rig with an inner diameter of 1.2 m which has two test trays (ConCap tray) and two chimney trays. It was found that the weir height affects only on the pressure drop. The recommended weir height for the ConCap tray must be 2.5 cm because of observed spray flow regime on the tray and experimental results in different weir height which shows no effect on the weeping and entrainment rates. Moreover, the hydraulic behavior of the tray in the lower operating limits was also investigated.