Sharif Digital Repository

Densities and viscosities of aqueous solutions containing sulfolane and ternary aqueous solutions of sulfolane and triethanolamine and ternary aqueous solutions containing sulfolane and disopropanolamine and also equilibrium surface tensions of the above ternary aqueous solutions were measured at temperatures ranging from (303.15 to 343.15) K and atmospheric pressure. The overall concentration of sulfolane, triethanolamine, and diisopropanolamine in solutions varied in the range of 0 to 16.5, 0 to 43, and 0 to 40 mass percent, respectively. Using the density, viscosity, and surface tension of pure water as the solvent, the corresponding experimental values obtained for the investigated... 

In this study, a hydrophilic metal-organic framework (MOF) was applied to improve the performance of a cellulosic membrane for forward osmosis (FO) desalination application. The characterization results confirmed that the MOF particles existed within the matrix of the modified membrane. The MOF loading led to adjustment of the membranes in terms of overall porosity, pore inter-connectivity and hydrophilicity. These features caused an improvement in the pure water permeability (72%) and reduce the structural parameter of the modified membrane to 136 μm. The FO water flux of the modified membrane enhanced by about 180% compared to an unmodified membrane, without decreasing its selectivity. FO... 

Estimating the feasibility of acid gas geological disposal requires the knowledge of the water content of the gas phase at moderate pressures and temperatures (typically below 50MPa, below 380K) and up to 6mol NaCl. In this paper, a non-iterative model is developed to predict the water content of sour and acid gases at equilibrium with pure water and brine. This model is based on equating the chemical potential of water and using the modified Redlich-Kwong equation of state to calculate the fugacity of the gas phase. The water content of pure CH4, CO2 and H2S are represented with average absolute deviations of less than 3.36, 7.04 and 8.4%, respectively. Experimental data of the water... 

The height of a dense layer underflow is defined as the interface between a dyed saline solution fluid and colorless ambient fluid. In this paper, the density current height or vision height of three-dimensional saline water under pure water is measured empirically, and the relation of this parameter with the location of maximum velocity is investigated. Because of the absence of a clear interface between the dense underflow and pure water, researchers were unable to define a unique parameter for the evaluation of density current height. The parameters used by some researchers include the height corresponding to the location of maximum, half-maximum, and quarter-maximum velocity in the... 

In this paper, the effect of different parameters on the thermal operation of a Closed Loop Pulsating Heat Pipe (CLPHP) has been investigated. These parameters include the working fluid, the inclination angle, the filling ratio, and the input heat flux. The effect of nanoparticle mass concentrations has been analyzed as well. It was observed that the CLPHP can decrease thermal resistance up to 11.5 times compared to the same empty copper tube with thermal resistance of 9.4 K/W. Optimum thermal operation for a system with the water-silver nanofluid was achieved at conditions of the 50% filling ratio with thermal resistance of 0.9 K/W, and for the water-titanium oxide system, the optimal... 

In this paper, the effect of several different parameters on the thermal resistance of a Closed Loop Pulsating Heat Pipe (CLPHP) has been investigated. These parameters include the working fluid, the inclination angle, the filling ratio and the heat influx. Also, the impact of using nanofluids with different nano-particle concentrations has been analyzed. It was observed that a CLPHP can increase the heat transfer up to 11.5 times compared to an empty pipe. Optimum performance for a system with the water-silver nanofluid was achieved at conditions of 50% filling ratio and 0.9 K/W of thermal resistance, and for the water-titanium oxide system, these optimal conditions were found to be 40%... 

To investigate boiling heat transfer characteristics of nanofluids, transient quenching experiments of a high temperature silver sphere in water-based nanofluids with Ag and TiO2 nanoparticles were performed. A silver sphere with a diameter of 10 mm and an initial temperature of 700 °C was quenched in these nanofluids at a temperature of 90 °C. The results showed a considerable reduction in the quenching ability of nanofluids compared to that of pure water. The presence of nanoparticles in water caused the film boiling mode to vanish at lower temperatures depending on the mixture concentration. Calculated heat transfer rates in nanofluids were lower than those in pure water. In the quenching... 

In this study, silicon microchannel heat sink (MCHS) performance using nanofluids as coolants was analyzed. The nanofluid was a mixture of nanoscale Cu particles and pure water with various volume fractions. Based on theoretical models and experimental correlations, the heat transfer and friction coefficients required in the analysis were used. In the theoretical model, nanofluid was treated as a single-phase fluid. In the experimental correlation, thermal dispersion due to particle random motion was included. The microchannel heat sink performances for a specific geometries with Wch = W fin = 100 μm and Lch =300 μm is examined. In this study, flow in laminar and turbulent regimes using the... 

Numerical investigation on the application of nanofluids in Micro-Pin-Fin Heat Sinks (MPFHSs) has been presented in this paper. To investigate flow and heat transfer behavior in MPFHS the three-dimensional steady Navier-Stokes and energy equations were discretized using a finite volume approach and have been solved iteratively, using the SIMPLE algorithm. DI-water is used as a base coolant fluid while the nanoparticles used in the present study are CuO nanoparticles with mean diameters of 28.6 and 29 nm and Al 2O 3 nanoparticles with mean diameters of 38.4 and 47 nm. The results show that (i) a significant enhancement of heat transfer in the MPFHS due to suspension of CuO orAl 2O 3...