Mass Transfer Studies in Three-phase Fluidized Bed Using Response Surface Method

Mass transfer characteristics of co-current three-phase fluidization were determined in terms of mass transfer coefficient and Sherwood number using Box-Behnken method. The experiment was carried out in a 5.4 cm I.D, 6 cm O.D and 160 cm high vertical Perspex column. Gypsum particles of diameter 0.0842 cm, 0.1676 cm and 0.2818 cm, water, and air were used as solid, liquid and gaseous phase respectively. Initially, the superficial liquid velocity was maintained constant and superficial gas velocities varied. After attaining steady state, at a particular gas velocity, the fluidized bed height and manometer readings were recorded for pressure drop estimation. The above-mentioned procedure was repeated for four different liquid velocities in a fluidized bed. The effect of individual phase holdup and mass transfer coefficient for various particle sizes with the specific liquid flow rates and gas flow rates were studied. It was observed that the mass transfer coefficient and Sherwood number increased with increase in superficial gas velocity and particle size in cocurrent three-phase fluidized bed. A quadratic model for bed porosity, gas holdup, Sherwood number and mass transfer coefficient were developed using response surface method (RSM)

Prediction of Air Flow and Temperature Distribution Inside a Yogurt Cooling Room Using Computational Fluid Dynamics

Air flow and heat transfer inside a yogurt cooling room were analysed using Computational Fluid Dynamics. Air flow and heat transfer models were based on 3D, unsteady state, incompressible, Reynolds-averaged Navier-Stokes equations and energy equations. Yogurt cooling room was modelled with the measured geometry using 3D design tool AutoCAD. Yogurt cooling room model was exported into the flow simulation software by specifying properties of inlet air, yogurt, pallet and walls of the room. Packing material was not considered in this study because of less thickness (cup-0.5mm, carton box-1.5mm) and negligible resistance created in the conduction of heat. 3D Computational domain was meshed with hexahedral cells and governing equations were solved using explicit finite volume method. Air flow pattern inside the room and the temperature distribution in the bulk of palletized yogurt were predicted. Through validation, the variation in the temperature distribution and velocity vector from the measured value was found to be 2.0oC (maximum) and 30% respectively. From the simulation and the measured value of the temperature distribution, it was observed that the temperature was non-uniform over the bulk of yogurt. This might be due to refrigeration capacity, air flow pattern, stacking of yogurt or geometry of the room. Required results were achieved by changing the location of the cooling fan

COMPARATIVEANALYSIS OF ADVANCED CONTROLLERS IN A HEAT EXCHANGER

Abstract: Temperature control of the shell and tube heat exchanger is characteristics of nonlinear, time varying and time lag. Since the temperature control with conventional PID controller cannot meet a wide range of precision temperature control requirement, we design temperature control system of the shell and tube heat exchanger by combining fuzzy and PID control methods in this paper. The simulation and experiments are carried out; making a comparison with conventional PID control showing that fuzzy PID strategy can efficiently improve the performance of the shell and tube heat exchanger

Prediction of gas holdup in the three-phase fluidized bed: air/Newtonian and non-Newtonian liquid systems

The application of the three-phase fluidization technology in wastewater treatment and other biochemical processes has been regularly addressed in the past decades. For the design and development of the threephase fluidized bed reactors, knowledge of the hydrodynamic parameter such as gas holdup is essential and hence in this paper an attempt has been made to study the effect of fundamental and operating variables on gas holdup. On the basis of the experimental results, a unified correlation has been developed to predict gas holdup in the fluidized bed using the Newtonian and the non-Newtonian liquids. The experimental results showed good agreement with those predicted according to the developed correlation

Treatability of resin effluents by electrochemical oxidation using batch recirculation reactor

Electro oxidation processes are developed throughout the world for ambient temperature destruction of organic wastes. Several of these processes are based on mediated electrochemical oxidation. This article presents the experimental results of electro chemical study based on mediated electrochemical oxidation process conducted for synthetic organic ion exchange resin materials. Investigation was carried out using the traditional noble metal oxide coated anode, ruthenium oxide-titanium and the mediator used for the experiment was ferrous sulphate, with sodium chloride as supporting electrolyte. The concentration of sodium chloride was maintained at 5, 8, 12 gm/L. The experiment was carried out in batch recirculation reactor with varied current densities for various flow rates. The study highlighted that in batch reactor set up the best effect of total organic content reduction was found to occur at 3.75 A/dm2 with flow rate of 20 L/h. The simulated studies were carried out for different volumes of effluent and current densities. A graphical analysis was made between the experimental and simulated values and it was found that both the values are very close

Removal of hydroquinone from water by electrocoagulation using flow cell and optimization by response surface methodology

In this study, hydroquinone was removed from water by electrocoagulation using flow electrolyzer in mono polar and bipolar configurations in a batch recirculation mode of operation. Treatment performances of such effluents have been evaluated in terms of chemical oxygen demand removal. The effect of important operating parameters such as current density, flow rate, concentration of hydroquinone and supporting electrolyte on the pollutant removal and energy consumption is critically evaluated. The experimental data were analyzed using response surface methodology (RSM).MaximumCOD removal inmonopolar configuration of 80.95% was noticed at condition of supporting electrolyte concentration 2.67 g L−1, flow rate 27 mL min−1, current density 0.7 A dm−2 at energy consumption of 2.36 kWh per kg of COD for the 1000 mg L−1 of hydroquinone concentration. In the case of bipolar configuration a maximum COD removal of 87.13 was noticed at: supporting electrolyte concentration 4 g L−1, flow rate 29.15 mL min−1, current density 1 Adm−2 at energy consumption of 8.495 kWh per kg of COD for the same hydroquinone concentration

International Journal of Pharma and Bio Sciences RESEARCH ARTICLE PHARMACY PRACTICE POTENTIAL RISK FACTORS FOR COGNITIVE DECLINE IN DIABETIC COHORT

OBJECTIVE: The objective of the study was to evaluate the association between Gender, Age and Social habits with regard to Cognitive dysfunction in Diabetic patients. Research Design: The study is a randomised prospective study on 500 diabetic patients of various socio demographic characteristics, extending over a period of eighteen months with baseline and follow up’s scheduled at every six months intervals with the aid of Mini Mental State Examination (MMSE scale). Results and Conclusion: Among Diabetic patients studied for cognitive dysfunction with regard to our study objective, it was evident that older Diabetic patients exhibited a potential decline in cognitive function, further more there was as significant impact of diabetes on cognitive function with regard to gender. Women with diabetes marked a high level of cognitive decline than men of the same age group. The study concluded that a social habit imparts a significant risk to cognitive functioning. This article can be downloaded from www.ijpbs.ne