Sharif Digital Repository

Using gas-liquid lifting pumps is a quite different technology for pumping two or three phase flows rather than other types of pumping systems. Therefore, finding performance characteristic chart for this type of pumping system seems to be necessary. In this type of pumping system, the liquid phase is pushed upward by the compressed air which has been injected in the bottom of upriser pipe of the pump. Therefore, compressed air acts as the driving force in gas lifting pumps instead of moving parts in ordinary pumps. It can be concluded that the definition of characteristic curve used for ordinary pump is not very appropriate for this type of pumping system. In this study, it has been... 

Airlift Systems (ALS) are widely used in various industrial applications. As the main part of the flow through ALS's upriser pipe, is formed by gas-liquid flow, the analysis of such systems will be accompanied by problems of two-phase flow modelling. Several effective variables are involved in ALS; thereupon comprehensive method is needed to consider these parameters. Exergy analysis can be considered as a simple solution for the realisation of the preferred domain of ALS's operation. Here, this method has been proposed to examine the performance of ALS. Based on thermodynamic principles, an analytical model has been implemented in each phase and the respective experimental data have been... 

Liquid-liquid two-phase flow is capable of boosting heat transfer in microdevices compared to the single-phase and gas-liquid flows. A thorough investigation is performed here to characterize the heat transfer in water-oil flow in a microtube. Finite element method along with the level-set model is employed for numerical simulation. A main part of this paper is devoted to studying the effect of wettability on the heat transfer performance. Four contact angles of 0°, 30°, 150°, and 180° are investigated, which revealed that the contact angle of 150° produces the highest Nusselt number (Nu). Triple points form at this contact angle, and the slugs slide on the wall, which results in more... 

A new approach has been presented to solve gas-liquid flow numerically in vertical pipes of air-lift pumps. To improve modelling, a new strategy has been employed with the capability of coupling the continuity and momentum equations and enforcing the role of pressure directly in the continuity equation. This is achieved via applying a novel scheme called the Physical Influence Scheme (PIS). The current finite volume solution is compared with other available numerical solutions. Indeed, they are in fair agreement. However, the present predictions are far superior to those obtained from an existing simple method, which is widely used in airlift pump modelling  

In the present work we studied the use of a membrane contactor system for simultaneous absorption of H2S and CO2 from a gas mixture similar to natural gas. MDEA solution and mixtures of MDEA/DEA and MDEA/MEA were used as absorbent liquid. PVDF and PSf hollow fiber membranes were used in the membrane contactor modules. Design of experiments were carried out by Taguchi method in a manner that a systematical investigation of the effect of operational parameters (temperature, pressure, gas and liquid flow rates, absorbent concentration and acid gas content of the feed), in addition to the effect of membrane material and absorbent liquid, was implemented on process performance parameters...