Iranian Association of Chemical Engineers(IAChE)Iranian Journal of Chemical Engineering(IJChE)1735-53976420091001A Simple One-Dimensional Model for Investigation of Heat and Mass Transfer Effects on Removal Efficiency of Particulate Matters in a Venturi Scrubber31415172ENJournal Article20160529<span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>In the present study a mathematical model is developed in order to examine the effects</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>of heat and mass transfers on removal efficiency of particulate matters in venturi type</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>scrubbers. The governing equations including the variations of the particulate</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>concentration, gas temperature, droplet temperature, diameter, and velocity are</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>obtained based on the conservation laws and are solved numerically. In order to</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>validate the model, necessary data was measured and collected in a commercial cement</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>plant that uses these types of scrubbers in air pollution control applications. A good</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>agreement between plant data and the model predictions is noticed in general. The</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>results obtained from the model reveal that the existance of temperature difference</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>between the gas and the liquid droplets decreases the overall removal efficiency of</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>particulate matters. This is due to sudden reduction ofrelative velocity between the gas</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>and droplets which is resulted from the existence ofheat and mass transfers between the</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>two fluids, especially in the throat section. In addition, the effects ofvarious operating</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>parameters on the extent ofreduction in the removal efficiency are examined. This study</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>confirms that in most industrial applications ofventuri scrubbers it is necessary to use a</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>direct or an indirect cooling tower in order to decrease the gas temperature before</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>entering the venturi.</em></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span><br style="font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" /><br class="Apple-interchange-newline" /></span>Iranian Association of Chemical Engineers(IAChE)Iranian Journal of Chemical Engineering(IJChE)1735-53976420091001Experimental Study on the Effect of Heat Loads, Fill Ratio and Extra Volume on Performance of a Partial-Vacuumed Thermosyphon152615173ENJournal Article20160529<span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>This paper reports a study on the effect of the heat flux, cooling water flow rate, fill</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>ratio and extra volume on the overall performance of a partially vacuumed</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>thermosyphon. A rig was made from a 1 m copper tube with an inner and outer</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>diameter of 17.5 and 19 mm. The heights of the evaporator, the adiabatic section and</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>the condenser are 40, 20 and 40 cm, respectively. The temperatures at different places</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>on the thermosyphon and on the inlet/outlet ofthe cooling water were measured. It was</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>observed that change in heat flux, fill ratio and employing different extra volumes, has</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>a significant effect on its performance. On the other hand, with changes in the cooling</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>water flow rate the performance ofthe thermosyphon was altered regarding the trapped</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>air movement. In order to illustrate the effect ofthe existence ofair in deactivating the</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>thermosyphon, the pipe was cooled down by disconnecting the evaporator power input.</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>It was seen that the thermosyphon loses its performance as the trapped gas occupies the</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>whole condenser. The whole study shows that due to the existence ofthe trapped air, the</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>heat loads can have significant effects on the thermosyphon performance.</em></span></span></span></span></span></span></span></span></span></span></span></span></span><br style="font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" /><br class="Apple-interchange-newline" /></span>Iranian Association of Chemical Engineers(IAChE)Iranian Journal of Chemical Engineering(IJChE)1735-53976420091001Optimization of Integrated Low-Temperature Gas Separation Processes Using SA Method and Different Refrigerants273315174ENJournal Article20160529<span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>In low-temperature processes, heat rejected from separation columns is removed by</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>refrigeration systems to heat sinks (reboilers & pre-heaters), process streams, other</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>refrigeration streams, or external utilities. The need for efficient utilization and</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>recovery of energy in sub-ambient gas separation processes is still challenging.</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>Performance and reliability of Simulated Annealing (SA) for simultaneous design and</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>optimization of such systems has been investigated previously. In this work, the effect of</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>different refrigerants satisfying a set of process cooling duties at different temperatures</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>is addressed. Cost reduction can be realized by encompassing both effective screening</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>of heat-integrated separation columns and selecting the best refrigerants. A 29.7% cost</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>savings has been shown through a case study. Afterwards, a comprehensive</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>thermodynamic analysis has been carried out on achieved solutions to verify the</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>accuracy of existing shortcut models and robustness of optimized structure. It has been</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>shown that exergy analysis using two different approaches (i.e. stream wise and unit</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>operation wise) are the same, which indicate the accuracy of the used models.</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>Moreover, we have indicated that both utility costs and exergy losses can be considered</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>as an objective function when optimizing the designs.</em></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span><br style="font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" /><br class="Apple-interchange-newline" /></span>Iranian Association of Chemical Engineers(IAChE)Iranian Journal of Chemical Engineering(IJChE)1735-53976420091001CFD Simulation of Catalytic Combustion of Benzene344415175ENJournal Article20160529<span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>This paper reports the result of CFD simulation of catalytic oxidation of benzene on</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>monolithic catalyst. The geometries ofthe catalyst and reactor were designed in Gambit</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>software and simulation of catalytic oxidation was carried out in fluent 6.2. Results of</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>simulation showed excellent agreement with the experimental data. This study</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>confirmed the accuracy of the used model in this simulation (Mars van Krevelen).</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>Furthermore, CFD made it possible to obtain a more accurate view ofheat transfer and</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>fluid flow. This study confirmed CFD is the best tool for study offluid regime and heat</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>transfer and especially, concentration of species, and surface deposition along the</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>reactor in the chemical process.</em> </span></span></span></span></span></span></span><br style="font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" /><br class="Apple-interchange-newline" /></span></span>Iranian Association of Chemical Engineers(IAChE)Iranian Journal of Chemical Engineering(IJChE)1735-53976420091001Numerical Study of Non-Newtonian Flow Through Rectangular Microchannels446115176ENJournal Article20160529<span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>A numerical investigation was carried out to solve the flow dimensionless partial</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>differential equations through rectangular microchannels. A purely viscous power law</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>model was used to characterize the flow behavior of non-Newtonian fluids. The flow</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>was assumed to be steady and laminar, and slip conditions were used as boundary</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>conditions at the walls. The problem was solved for different power law indices as well</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>as for various rectangular aspect ratios. Results showed that the effects ofslip velocity</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>on dilatant fluids are more pronounced than that for pseudoplastic fluids. An increase</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>in the power law index enhances the product of the friction factor and the Reynolds</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>number, as well as the dimensionless incremental pressure drop and the dimensionless</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>maximum velocity, while the hydrodynamic entrance length decreases. Results</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>emphasize the significant effects of channel aspect ratio on the hydrodynamic flow</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>behavior through microchannels.</em> </span></span></span></span></span></span></span></span></span></span><br style="font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" /><br class="Apple-interchange-newline" /></span></span>Iranian Association of Chemical Engineers(IAChE)Iranian Journal of Chemical Engineering(IJChE)1735-53976420091001Calculation of Physical Properties of the Methanol-Water Mixture Using Molecular Dynamics Simulation627215177ENJournal Article20160529<span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>In this study some properties ofthe methanol-water mixture such as diffusivity, density,</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>viscosity, and hydrogen bonding were calculated at different temperatures and</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>atmospheric pressure using molecular dynamics simulations (MDS). The results were</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>compared with the available experimental data as well as some theoretical models;</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>overall indicating a good agreement. This shows the useful and effective application of</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>MDS for determination ofphysical properties.</em> </span></span></span></span><br style="font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" /><br class="Apple-interchange-newline" /></span></span>Iranian Association of Chemical Engineers(IAChE)Iranian Journal of Chemical Engineering(IJChE)1735-53976420091001Simultaneous Effects of Ionic Surfactant and Salt on Drop-Interface Coalescence738615178ENJournal Article20160529<span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>In this research, the effect ofmixed salts together with mixed ionic surfactants on dropinterface coalescence time was studied for the system of water (d) / toluene(c) as a</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>model system. Sodium dodecyl sulfate (SDS) and cetyl trimethyl ammonium bromide</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>(CTAB) as anionic and cationic surfactants were used. Sodium chloride (NaCl) and</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>magnesium sulfate were used as salts. In the first stage of experiments, the system of</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>water and toluene was influenced separately with SDS+NaCl, SDS+MgSO</em><span style="font-size: 6pt; color: #000000; font-style: normal; font-variant: normal;"><em>4</em><span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>,</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>CTAB+NaCl and CTAB+MgSO</em><span style="font-size: 6pt; color: #000000; font-style: normal; font-variant: normal;"><em>4</em><span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>. It was observed that drop size increased with</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>SDS+NaCl and also with SDS+MgSO</em><span style="font-size: 6pt; color: #000000; font-style: normal; font-variant: normal;"><em>4</em><span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>. Partial coalescence times increased for all</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>systems. Overall, this increase of coalescence time was more obvious when CTAB was</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>applied. Also reduction in drop size was observed. In the case ofmixed surfactants with</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>single salt, it was observed that partial coalescence was suppressed for the system with</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>(SDS+CTAB)+MgSO</em><span style="font-size: 6pt; color: #000000; font-style: normal; font-variant: normal;"><em>4</em><span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>. On the other hand, drop size decreased and total coalescence</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>time increased. This may be due to the difference between the anions and cations ofthe</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>two salts. For the case ofmixed surfactants with mixed salts, drop size and coalescence</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>time decreased.</em> </span></span></span></span></span></span></span></span></span></span></span></span><br style="font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" /><br class="Apple-interchange-newline" /></span></span></span></span></span></span></span></span></span></span>