Swelling and Gelation Time Behavior of Sulfonated Polyacrylamide/Chromium Triacetate Hydrogels

A hydrogel was prepared by crosslinking of aqueous solutions of sulfonated polyacrylamide/chromium triacetate for use in water shut-off operations in oil reservoirs. The effects of pH, salinity, retarder and temperature, as well as co-polymer and crosslinker concentration, on the gelation time were investigated. The results indicated that as temperature increased, gelation occurred more rapidly. The activation energy was measured as about 86 kJ/mol. The effects of initial pH and retarder on the gelation time were also examined. The results showed that addition of retarder and increasing of pH increased and decreased the gelation time, respectively. The increase of co-polymer concentration in solution increased the gel swelling. However, the increase of crosslinker concentration decreased the gel swelling. In the presence of electrolytes, the gel swelling decreased by about 80%. Finally, some usable practical recommendations are offered for the gelling systems in reservoirs.     

The effect of rib shape on the behavior of laminar flow of oil/MWCNT nanofluid in a rectangular microchannel

Journal of Thermal Analysis and Calorimetry - In this research, the laminar and forced flow and heat transfer of oil/multi-walled carbon nanotubes nanofluid in a microchannel have been numerically...     

Methane hydrate stability in the presence of water-soluble hydroxyalkyl cellulose

The effect of low-dosage water-soluble hydroxyethyl cellulose (approximate MW～90,000 and 250,000) as a member of hydroxyalkyl cellulosic polymer group on methane hydrate stability was investigated by monitoring hydrate dissociation at pressures greater than atmospheric pressure in a closed vessel. In particular, the influence of molecular weight and mass concentration of hydroxyethyl cellulose (HEC) was studied with respect to hydrate formation and dissociation. Methane hydrate formation was performed at 2℃ and at a pressure greater than 100 bar. Afterwards, hydrate dissociation was initiated by step heating from -10℃ at a mild pressure of 13 bar to 3℃, 0℃ and 2℃. With respect to the results obtained for methane hydrate formation/dissociation and the amount of gas uptake, we concluded that HEC 90,000 at 5000 ppm is suitable for long-term gas storage and transportation under a mild pressure of 13 bar and at temperatures below the freezing point.     

Numerical study on the effects of geometrical parameters and Reynolds number on the heat transfer behavior of carboxy-methyl cellulose/CuO non-Newtonian nanofluid inside a rectangular microchannel

Journal of Thermal Analysis and Calorimetry - Present work studies the effects of microchannel height and Reynolds number on the temperature distribution behavior, pressure drop, and Nusselt number...     

Generating an adaptive multiresolution image analysis with compact cupolets

We present an efficient control scheme for stabilizing unstable periodic orbits of chaotic systems. The resulting orbits are called cupolets and have been proven to be useful in the representation of oscillatory or quasi periodic signals such as appear in music and image compression (Short et al., AES 118th Convention preprint 6446, May 2005; Short et al., AES 119th Convention preprint 6588, October 2005). In this paper we show that these cupolets can be used effectively to produce an adaptive basis for the space of real-valued functions of a discrete variable. From this basis, we construct a multiresolution analysis which allows for the approximation of signals at different resolution levels and apply it to image compression. This adaptive multiresolution analysis provides an interesting continuum between Fourier analysis and wavelet analysis.     

Numerical simulation of transient mixed convection of water–Cu nanofluid in a square cavity with multiple rotating cylinders having harmonic motion

Journal of Thermal Analysis and Calorimetry - Mixed convection in a lid-driven square cavity with different walls temperature in the existence of four rotating cylinders having harmonic motion is...