Showing papers in "International Journal of Engineering - Transactions C: Aspects in 2019"

Energy and Exergy Analysis of a New Power, Heating, Oxygen and Hydrogen Cogeneration Cycle Based on the Sabalan Geothermal Wells

Abstract: In this paper, a new power, heating and hydrogen cogeneration cycle from Sabalan geothermal two wells is proposed and analyzed. In the proposed system, a new double flash cycle and organic Rankine cycle are used for power production. A proton exchange membrane (PEM) is also used for hydrogen production and the domestic water heater is used for heating. The impacts of some design parameters, such as separators pressures, evaporator temperature, pinch point temperature difference and PEM temperature on the integrated system performance are investigated and then optimization is done from exergy point of view for three considered scenarios. According to the optimization results, the value of heating, net output power, hydrogen production and thermal and exergy efficiencies of the cogeneration system are obtained as 15751 kW, 18436 kW, 11.13 kg/h, 29.48% and 65.23%, respectively.

Investigation of the Effect of L-Ascorbic Acid on Class G Oil Well Cement

Abstract: Various chemicals can have different effects on the properties of the cement slurry. In this paper, the different effects of L-ascorbic acid have been investigated on the important parameters of cement slurry made from class G oil well cement. These parameters included the amount of free fluid, rheological properties, Thickening Time, and compressive strength. Several cement slurries were made with different dosages of L-ascorbic acid. By increasing the amount of L-ascorbic acid, free fluids were decreased and rheological properties of the slurries were improved. This improvement in the amount of free fluid and rheological properties continued with an increase of L-ascorbic acid. Increasing the dosage of L-ascorbic acid to 0.03% by weight of cement, decreased the thickening time and increased the compressive strength. In other words, L-ascorbic acid acted as an accelerator up to 0.03% by weight of cement and would have the role of a retarder in higher value.

Static Coil Design Considerations for the Magnetic Resonance Imaging

Abstract: One of the main challenges in developing magnetic resonance imaging (MRI) systems is to create a static coil that needs to generate magnetic field density along with the characteristics of optimal homogeneity and magnitude size. To do this, two N42 Block PMs are used and the iron core is designed and optimized in accordance with the dimensions of PM pieces using ANSYS Maxwell software. Then, all iron parts are lathed, the yoke pieces and pole spacers are welded. In addition, PM and pole pieces are installed. Finally, measurement is done by Lutron to evaluate the static coil performance.

A New Approach to Provide High Water Permeable Polyethersulfone based Nanofiltration Membrane by Air Plasma Treatment

Abstract: In this study, polyethersulfone based nanofiltration membranes were modified by air plasma generated through dielectric barrier discharge to increase the membrane hydrophilicity aiming to improve the separation and antifouling characteristics. The effect of plasma time on the physico-chemical and separation properties of membrane was investigated. The PES nanofiltration membranes were fabricated by the solution casting technique associated with phase inversion method. The FTIR spectra showed formation of imine and amine functional groups on the membrane surface. The water contact angle decreased form 58 ° to 31 ° by plasma treatment which produces more hydrophilic surface. SEM and SOM images demonstrated that the surface morphology was changed due to ions collision with membrane surface bombardment. AFM results indicated that membrane roughness was initially enhanced by plasma treatment up to 1 minute, and then decreased again by a further increase of treatment time. Membrane water flux increased from 10.05 (L/m2.h) to 35.17 (L/m2.h) remarkably by plasma treatment up to 1 minute and then decreased again at longer treatment times. An opposite trend was observed for the salt rejection of membranes. The water flux was enhanced ~270% for the modified membrane at 2 min plasma treatment whereas rejection declined less than 18%.

Reversible Logic Multipliers: Novel Low-Cost Parity-Preserving Designs

Abstract: Reversible logic is one of the new paradigms for power optimization that can be used instead of the current circuits. Moreover, the fault-tolerance capability in the form of error detection or error correction is a vital aspect for current processing systems. In this paper, as the multiplication is an important operation in computing systems, some novel reversible multiplier designs are proposed with the parity-preserving property which will be useful for error detection. At first, two optimal signed serial multipliers are presented based on the Booth’s algorithm and its enhanced version called the K-algorithm, utilizing the new arrangements of reversible gates. Then, another low-cost serial multiplier is proposed based on the conventional Add & Shift method to be utilized in the applications in which unsigned numbers are used. Finally, a new signed parallel multiplier is proposed based on the Baugh-Wooley method that is useful for speed-critical applications. The comparative results showed that the proposed multipliers are much better than the existing designs regarding the main criterions used in reversible logic circuits including quantum cost, gate count, constant inputs, and garbage outputs.