hasan ghafori

The research projects conducted in the field of biogas shows that the type of reactor and the composition of different animal wastes have a direct effect on the amount of biogas extraction. Therefore, the main goal of this research is to design and build a multi-bed reactor with a new capability and investigate the effect of the combination of livestock and poultry waste on the gas production process. For this purpose, a multi-bed cylindrical reactor equipped with a separate stirrer for each bed was designed and built, and the effect of different combinations of livestock and poultry wastes in three levels including 60% by weight of chicken waste and 40% by weight of cow waste, 50% by weight of chicken waste and 50% by weight of cow waste, and finally 40% by weight of chicken waste and 60% by weight of cow waste. , the compound concentration at two levels of TS=10% and TS=15% and the reactor temperature at two levels of 37 and 40 degrees Celsius were examined on the pH and percentage of extracted biogas. The results showed that the use of a bed stirrer in this type of reactor increased the volume of produced gas by 17%. Increasing the ratio of animal waste to poultry, balanced the acidity of the environment and finally increased the percentage of extracted biogas. Diluting the composition from TS=15% to TS=10% led to an increase in the pH level and approaching the neutral environment. Also, reducing the temperature of the reactor from 40°C to 37°C increased the percentage of extracted biogas by 8%.

The quality of drying in solar dryers depends on the heat transfer inside the dryer and performance parameters such as pressure drop and efficiency factor. Therefore, the purpose of this research is to investigate the effect of dryer geometry, vortex flow generator, radiation intensity and Reynolds number on heat transfer, pressure drop and performance evaluation coefficient of solar dryer. For this purpose, three different geometries were considered, including a channel with a completely smooth surface, a channel with a curved surface, and a channel with a flow perturber, all three of which were exposed to specific and uniform solar heat flux radiation. For each of the above modes and for Reynolds numbers 3000, 4500, 6000 and 7500 and solar radiation intensities of 700, 800, 900, 1000 and 1100 wat/m2, the amount of average Nusselt number, pressure drop inside the channel and performance evaluation coefficient calculated. The results showed that the use of a vortex generating channel and a channel with concave surface compared to a simple channel increases the amount of heat transfer. Also, as the Reynolds number of the flow increases, while the pressure drop increases, the average Nusselt number also increases.

The mill is one of the equipments which used in agricultural products processing. Impact or hammer mills are used for crushing grain, animal feed and spices due to their simplicity and ease of operation. In these mills, the crushing operation is done by impacts from the blades to the grains. The movement of the blade in the grain, after a relatively short period of time, leads to wear and erosion on the impacting edge of the blade. Frequent replacement of blades requires cost and time, which reduces the efficiency of the device and increases the cost of the product. Therefore, in this study, the evaluation of mechanical properties of steels with different alloys is considered as a suitable alternative to existing hammer mill blades. For this purpose, the effect of blade material on four levels and the effect of heat treatment in two different cycles for each sample on the hardness and abrasion resistance indices were investigated by laboratory test and practical test. Hardness test and abrasion test were performed using a hardness tester and pin on disk method in the metallurgical laboratory of the Islamic Azad University of Majlesi branch. The practical test of the blades was performed by installing the blades on the rotor of the milling machine and measuring their amount of wear in terms of mass losses, after grinding 1800 tons of grain. The results showed that DIN X 210Cr12 steel with SPK brand after quenching heat treatment cycle in oil, has more hardness and higher abrasion resistance than other samples. Appearance examination of the blades in the practical test showed that the DIN X 210Cr12 steel blades with different heat treatment cycles has the least erosion at the impact edge of the blade and is recommended as a suitable replacement for current blades.

Engines with variable poppet valve timing systems are among numerous efforts that aim to reduce engine emissions and/or increase efficiency. In the present paper we have investigated the stability of a magnetic valve system in MATLAB. First we designed the magnet and interactive forces inside the electromagnetic valve system, then we produced a mechanical model for the system by using a two degree of freedom mass and spring system and finally designed a PID controller to maintain system stability. The results of the present study indicate that the controller had decreased the maximum valve displacement domain and duration from 2 mm to 0.001 mm and 0.1 seconds to 0.022 seconds, respectively. Poppet valve settling speed was 0.0126 and had a standard deviation of 0.1304 while the armature settling speed was 0.0184, with a standard deviation of 0.1363. Passes for the phases were -37.5 and -169, with gains of 10.3 and -9.35.

Nowadays, compared to the past, the growth of technology in suspension systems have led the magnetic bearings to a more powerful and economical design. Such bearings proved to have lots of benefits such as performance capability in high speeds and the ability to perform action without lubrication in different performances. That cause a decrease in the environmental and system pollution and makes it possible to work in vacant environments. Such bearings which work without friction show to have little attrition. In This paper, investigates the operation of magnetic bearing having 8 and 16 polar at a velocity rate at 30000 rpm and gap tolerance ranging from 2 to 0.5 mm. The magnetic for condition simulates based on finite element by optimizing the best mesh measurement.