Sharif Digital Repository

A general investigation of the thermal conductivity of natural gas as a function of temperature, pressure and composition was carried out to develop a generalized correlation. The model obtained was based on 731 data points of 42 binary mixtures in wide ranges of pressures (0.1-300MPa), temperatures (220-425K) and specific gravities (0.626-1.434). Correction terms for non-hydrocarbons of carbon dioxide and nitrogen were up to 87.8 and 82.8 of mole percent, respectively. The arithmetic average of the model's absolute error was found to be 5.69%, which is acceptable in engineering calculations  

A new generalized and non-group contribution method has been developed to predict critical temperature (Tc), critical pressure (Pc), critical volume (Vc) and acentric factor (ω) for pure substances and petroleum fractions based on two types of input parameters. This method can take either refractive index and molecular weight or refractive index and normal boiling point as its input. Since refractive index cannot be obtained for an unknown mixture (petroleum fraction), in order to apply the proposed method for petroleum fractions, refractive index is converted to mass density at 293K using the one-third rule. Moreover, the proposed correlation is capable of predicting the properties using... 

This paper presents an experimental study on the interfacial characteristics of rammed earth materials stabilized with the combination of cement and alkali-activated fly ash (AAFA), an eco-friendly alternative for cement. Several direct shear tests were conducted to obtain cohesion and friction angle to do so. Moreover, pulse velocity and unconfined compression tests were exploited to assess other physical and mechanical properties of this material. Through the methodology used in this work, it is shown that the replacement of cement with AAFA dramatically improved cohesion, compressive strength, and pulse velocity. However, no general correlation was observed for the friction angle. © 2021,... 

Magnetic convection heat transfer in a two-dimensional square cavity induced by magnetic field gradient is investigated numerically using a semi-implicit finite volume method. The side walls of the cavity are heated with different temperatures, the top and bottom walls are isolated, and a permanent magnet is located near the bottom wall. Thermal buoyancy-induced flow is neglected due to the nongravity condition on the plane of the cavity. Conditions for the different values of non-dimensional variables in a variety of ferrofluid properties and magnetic field parameters are studied. Based on this numerical analysis, a general correlation for the overall Nusselt number on the side walls is... 

Excess pressure drop induced by inertial effects limits the applicability of Darcy's law for modeling of fluid flow through porous media at high velocities. It is expected such additional pressure drop is influenced by pore/morphology of porous media. This work concerns with fundamental understanding of how throat curvature affects intrinsic properties of porous media at non-Darcy flow conditions using network modeling. Conical, parabolic, hyperbolic, and sinusoidal capillary ducts with three types of imposed anisotropy are used to construct the network in a more realistic manner. Solutions of one dimensional Navier-Stokes equation for incompressible fluid flow through converging/diverging... 

In this work, PC-SAFT, an equation of state based on perturbation theory, is applied to predict the reservoir fluids phase behavior. PC-SAFT parameters for pure components have previously been assessed, but they cannot be determined for petroleum fractions with unspecified components and composition. In order to remove this difficulty and making use of PC-SAFT model in the reservoir fluids simulations, a new approach is studied which leads to appearing generalized correlations for the estimation of PC-SAFT parameters for petroleum cuts and plus fractions using only their molecular weight and specific gravity, without the essential need for the characterization of petroleum fractions in... 

This paper presented a numerical study that predicts critical mass flow rate, pressure, vapor quality, and void fraction along a very long tube with small diameter or capillary tub under critical condition by the drift flux model. Capillary tubes are simple expansion devices and are necessary to design and optimization of refrigeration systems. Using dimensional analysis by Buckingham's π theory, some generalized correlations are proposed for prediction of flow parameters as functions of flow properties and tube sizes under various critical conditions. This study is performed under the inlet pressure in the range of 0.8 ≤ pin ≤ 1.5Mpa, subcooling temperature between 0 ≤ ΔTsub ≤10 °C. The...