Hameed B. Mahood

Analytical Modelling of a Spray Column Three-Phase Direct Contact Heat Exchanger

An analytical model for the temperature distribution of a spray column, three-phase direct contact heat exchanger is developed. So far there were only numerical models available for this process; however to understand the dynamic behaviour of these systems, characteristic models are required. In this work, using cell model configuration and irrotational potential flow approximation characteristic models has been developed for the relative velocity and the drag coefficient of the evaporation swarm of drops in an immiscible liquid, using a convective heat transfer coefficient of those drops included the drop interaction effect, which derived by authors already. Moreover, one-dimensional energy equation was formulated involving the direct contact heat transfer coefficient, the holdup ratio, the drop radius, the relative velocity, and the physical phases properties. In addition, time-dependent drops sizes were taken into account as a function of vaporization ratio inside the drops, while a constant holdup ratio along the column was assumed. Furthermore, the model correlated well against experimental data.

HEAT TRANSFER MODELLING OF TWO-PHASE BUBBLES SWARM CONDENSING IN THREE-PHASE DIRECT-CONTACT CONDENSER

An analytical model for the convective heat transfer coefficient and the two-phase bubble size of a three-phase direct contact heat exchanger was developed. Until the present, there has only been a theoretical model available that deals with a single two-phase bubble and a bubble train condensation in an immiscible liquid. However, to understand the actual heat transfer process within the three-phase direct contact condenser, characteristic models are required. A quasi - steady energy equation in a spherical coordinate system with a potential flow assumption and a cell model configuration has been simplified and solved analytically. The convective heat transfer in terms of Nu number has been derived, and it was found to be a function to Pe number and a system void fraction. In addition, the two-phase bubble size relates to the system void fraction and has been developed by solving a simple energy balance equation and using the derived convective heat transfer coefficient expression. Furthermore, the model correlates well with previous experimental data and theoretical results.

Measuring the Overall Volumetric Heat Transfer Coefficient in a Vapor-Liquid–Liquid Three-Phase Direct Contact Heat Exchanger

ABSTRACT An experimental investigation of the volumetric heat transfer coefficient in a three-phase direct contact condenser was carried out. A 75-cm-long cylindrical Perspex column with a 4 cm diameter was used. Only 48 cm of the column was utilised as the active direct contact condensation height. Pentane vapor at three different initial temperatures (40°C, 43.5°C, and 47.5°C), with differing mass flow rates, and tap water at a constant initial temperature (19°C) with five different mass flow rates were employed as the dispersed phase and the continuous phases, respectively. The results showed that the volumetric heat transfer coefficient increased with increasing mass flow rate ratio (variable dispersed phase mass flow rate per constant continuous phase mass flow rate), the continuous phase mass flow rate and holdup ratio. An optimal value of the continuous phase mass flow rate is shown for an individual dispersed phase mass flow rates. This value increases with increasing vapor (dispersed) phase mass flow rate. Furthermore, it was observed that the initial driving temperature difference had no effect on the volumetric heat transfer coefficient. While, the temperature gained by the continuous phase has a considerable effect.

Galvanic Corrosion of Steel–Brass Couple in Petroleum Waste Water in Presence of a Green Corrosion Inhibitor: Electrochemical, Kinetics, and Mathematical View

Control of galvanic corrosion of steel–brass couples in petroleum waste water solution by Curcuma longa was studied at different temperatures, inhibitor concentrations, and velocities using the electrochemical polarization technique. Inhibition efficiency was increased with the increase in inhibitor concentration and decreased with both rises in temperature and solution velocity. Maximum inhibitor efficiency was 94.9% in static solution, higher level of inhibitor concentration and lower level of temperature. The adsorption of Curcuma longa obeyed a Langmuir adsorption isotherm by formation of spontaneous physical layer on the metal surface. Scanning electron microscopy of the metal surface revealed that damage was lower in the presence of Curcuma longa. Activation studied via Arrhenius equation showed that the adsorb layer on the surface increases the energy barrier for corrosive dissolution which is also supported by the higher values of activation energy. Mathematical and statistical analyses were also used as a successful tool to correlate the corrosion rate data with operating conditions.

Removal Efficiency of Solid Particles from Raw Water Using AFM Grade-2 Media: Case Study

This paper describes the removal efficiency of solid particles from raw water by activated crushed glass media and compares its efficiency with sand media. In this study, activated crushed glass media (AFM) grade 2 and 14/25 sand media were experimentally tested using a filtration pilot plant unit in CORA laboratory. Turbidity level of the effluent used was around 70 NTU, which has been selected from turbidity profile test of Wey River (Guildford/UK) on March 2010. Although, both of these filter media were not identical in porosity and particle size distribution, the experimental results showed that AFM media garde-2 exhibited a high capability to remove solid particles from the raw water besides of it other advantages. Also, the capability of AFM for removing solid particles was slightly poorer than those of 14/25 sand media.

Experimental and Theoretical Studies of Mild Steel Corrosion Inhibition in Phosphoric Acid Using Tetrazoles Derivatives

The electrochemical behavior of mild steel in phosphoric acidic solutions was investigated in the absence and presence of three heterocyclic tetrazoles derivatives using polarization and electrochemical impedance techniques. The corrosion rate is affected by both acid and inhibitors concentration. Inhibitors reduce the corrosion rate values by suppression of anodic dissolution of steel rather than the cathodic process of hydrogen evolution. Corrosion potential values were shifted to positive direction. Addition of inhibitors did not change the mechanism of corrosion process, which indicates that these compounds act by forming a film on metal surface. Impedance measurements showed that the charge transfer resistance increases and the double layer capacity decreases with addition of inhibitors. Charge transfer resistance increased with time. Maximum inhibitor efficiency was 71.5%, which leads to conclude that the studied inhibitors represent moderate anticorrosion materials. Quantum chemical investigations were also used to optimize the chemical structure of inhibitors.