in this study, the diffusivity and volumetric mass transfer coefficients for the extraction of β-carotene from crude palm oil using co2 solvent in supercritical fluid were determined in the pressure range of 7.5-17.5 mpa and temperature range of 80-120 ºc. for this purpose, a statistical method was applied in order to minimize the number of experiments required. the volumetric mass transfer coe...

a one–dimensional, transient and thermal degradation model for predicting responses of composite materials when are exposed to the fire is presented. the presented model simulates ablation of composites with different layers of materials and considers material properties as functions of temperature. the reactions are modeled by using arrhenius-type parameters and density-temperature diagrams wh...

recently, the production of biosurfactants in bioreactors and their use in various pharmaceutical,chemical and food industries have been developed. optimum production is directly related to the physicochemicalcondition of culture medium (such as ph and temperature) and engineering parameters of bioreactors (such asaeration rate, volume of operation and the amount of energy input). understanding...

this study aimed to find an appropriate way to minimize water utility in the petrochemical and petroleum industries. for this purpose, tehran oil refinery was chosen to analyze feasibilities of regeneration, reuse and recycling in the water network. in this research, two key contaminants including cod and hardness were analyzed. amount of freshwater was reduced about 180 m3/h (53%) and 216.88 m...

a numerical model is developed to simulate the transport phenomena in the flow channel between parallel plates with porous and non-porous (or impermeable) walls. the continuity and momentum equations were solved first, assuming the wall reynolds number in the range of with the suction or injection of air at a speed equal to the uniform inlet velocity. the results show that at constant inlet and...

active carbon is char derived from pyrolysis of organic materials. it has a high porosity level and is used to filter fluids. many types of agricultural materials are used to produce active carbon. the trunk of the date palm, with its low density and high porosity, has great potential for producing active carbon. in this research, the bark was pyrolyzed at 450°c for 60 min to produce active car...

proper estimation of droplet growth rate plays a crucial role on appropriate prediction of supersonic separators performance for separation of fine droplets from a gas stream. up to now, all available researches employ empirical or semi-empirical correlations to define the relationship between droplet growth rate (dr/dt) and other operating variables such as temperatures (t and tl), pressure (p...

recently, the production of biosurfactants in bioreactors and their use in various pharmaceutical,chemical and food industries have been developed. optimum production is directly related to the physicochemicalcondition of culture medium (such as ph and temperature) and engineering parameters of bioreactors (such asaeration rate, volume of operation and the amount of energy input). understanding...

nowadays, hydrogels are widely used as wound dressings in biomedical applications. similar to other types of the moist (wet) wound dressings, it is necessary to have sufficient information about their dehydration kinetics during the pre-usage period (e.g. storage duration) and also the wound healing process. in this work, hydrogel wound dressings based on polyvinyl alcohol were prepared by cycl...