Mass Transfer Rate Enhancement in Sparged Vessel for Ammonia-Water Nano-Fluid in VARS by Adding Nanoparticles

2020 ◽  
Author(s):  
Rahul Bhujbal ◽  
Sanjay Nakate ◽  
Sunil V. Dingare
Keyword(s):  
Mass Transfer ◽  
Transfer Rate ◽  
Numerical Study ◽  
Mass Transfer Rate ◽  
Solution Flow Rate ◽  
Low Grade ◽  
Efficient Design ◽  
Operation Condition ◽  
Solution Flow ◽  
Ammonia Water

Abstract The refrigeration systems are used in domestic and commercial freezing applications. These systems are needed to be used energy efficiently to get the economic operation condition. The vapor compression refrigeration cycle (VCR) is getting replaced by vapor absorption refrigeration system (VARS) as they can use low grade energy. This VARS can be used by making use of waste energy in the form of heat which is readily available for many applications. Performance of the VARS is dependent on the generator and absorber performance. In absorber it is based on the amount of refrigerant absorbed and the solution flow rate. Experimental and Numerical study of bubble absorber and effect of nanoparticle on ammonia water mass transfer is carried out. In this study, different designs for the absorber chamber are viewed and compared together, based on the research did earlier. Looking at the aspects of bubble type absorber designs, these designs give better mass transfer performance as compared to other designs. These designs may be improved to get the energy efficient design of the absorber. Present study includes the enhancement of mass transfer rate by the addition of nanoparticles using aluminum oxide (Al2O3). Here, sparged vessels with NH3-H2O binary fluid are arranged with varying percentage of nanoparticle (Al2O3). This study includes the study of mass transfer enhancements by using nanoparticles. Based on the experimental results carried out for the varying mass flow rates it is found that the mass transfer rate is enhanced significantly, it is because the interfacial area is enhanced by the addition of nanoparticles to the base fluids.

scholarly journals Numerical Study of Natural Convective Heat and Mass Transfer in an Inclined Porous Media

2018 ◽  
Vol 8 (4) ◽  
pp. 3223-3227
Author(s):  
A. Latreche ◽  
M. Djezzar
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Transfer Rate ◽  
Numerical Study ◽  
Mass Transfer Rate ◽  
Momentum Conservation ◽  
Conservation Equation ◽  
Coupled Equations ◽  
Dimensional Parameters ◽  
Finite Volume Approach

In this study, two dimensional natural convection heat and mass transfer generated in an inclined rectangular porous cavity filled with Newtonian fluid has been investigated numerically. The cavity is heated and cooled along horizontal walls while the solutal gradient is imposed horizontally. The physical model for the momentum conservation equation makes use of the Darcy model, and the set of coupled equations is solved using a finite volume approach. The successive-under-relaxation (SUR) method is used in the solution of the stream function equation. The results are presented graphically in terms of streamlines, isotherms and iso-concentrations. The heat and mass transfer rate in the cavity is measured in terms of the average Nusselt and Sherwood numbers for various non-dimensional parameters.

scholarly journals Removal of Congo Red from Aqueous Solution by Circulating Fluidized Bed(CFB)

2021 ◽  
Vol 28 (2) ◽  
pp. 01-07
Author(s):  
Hamza Q. Ali ◽  
Ahmed A. Mohammed
Keyword(s):  
Mass Transfer ◽  
Fluidized Bed ◽  
Flow Rate ◽  
Congo Red ◽  
Circulating Fluidized Bed ◽  
Mass Transfer Rate ◽  
Breakthrough Curves ◽  
Solution Flow Rate ◽  
Solution Flow ◽  
Bed Height

In this study circulating fluidized bed was adopted to remove of Congo Red from wastewater using Eichhornia crassipes as a adsorbent. Solution flow rate(6,12 and 18)l/hr, bed height(2,4 and 6) cm and Congo Red initaial concentration (10,25 and 50)mg/l were examined in experiments to show their effects on breakthrough curves and time required to reach the adsorbent to fully saturated curve. The mass transfer coefficient "KL"decreased with decreasing the liquid flow rate. The minimum fluidization velocities of bed found equal to 1.6, 2, 2.5 mm/s for heights of 2, 4,6 cm respectively. The increasing of the bed height will increase the contact time of the solute in the bed, and these improve the solute removal efficiency. the increasing in flow rate and initial concentration will increase the mass transfer rate.

Numerical Study on Boiling Mechanism and Rapid Phase Transfer Phenomenon of LNG Discharging on Water

2012 ◽  
Vol 516-517 ◽  
pp. 97-106 ◽  
Author(s):  
Bin Zhang ◽  
Wan Qing Wu ◽  
Jian Wei Zhang
Keyword(s):  
Mass Transfer ◽  
Transfer Rate ◽  
Water Surface ◽  
Phase Transfer ◽  
Numerical Study ◽  
Mass Transfer Rate ◽  
Initial Time ◽  
Rapid Phase ◽  
Boiling Mechanism ◽  
Superheat Limit

Abstract. Aiming at analyzing boiling mechanism and confirming rapid phase Abstract. Aiming at analyzing boiling mechanism and confirming rapid phase transfer (RPT) taking place conditions of LNG discharging on water. The models of pool spreading, heat and mass transfer rate and LNG’s property are coupled in this paper. The conditions of RPT has been confirmed, which included LNG directly contacting with water and the water temperature should higher than LNG’s superheat limit temperature, but the RPT would not take place if the LNG boils on ice. The model of LNG discharging on water has been established in this paper, which is used to simulate Boe and Burro-9 experiments. The results showed that the models can simulate evaporation and boiling rate well, and can be used in predicting the initial time of RPT happening when the discharging process is calm and the location of discharging is near the water surface.

Numerical Study on the Characteristics of Natural Supercavitation by Planar Symmetric Cavitators With Streamlined Headforms

2017 ◽  
Author(s):  
Zhi-Ying Zheng ◽  
Lu Wang ◽  
Qian Li ◽  
Yue Wang ◽  
Wei-Hua Cai ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Liquid Phase ◽  
Vapor Phase ◽  
Transfer Rate ◽  
Numerical Study ◽  
Mass Transfer Rate ◽  
Three Dimensional ◽  
Pressure Drag ◽  
Hyperbolic Cosine ◽  
Blade Shape

A novel supercavitation-based device named Rotational Supercavitating Evaporator (RSCE) was recently designed for desalination. In order to improve the blade shape of rotational cavitator in RSCE for performance optimization and then design three-dimensional blades, two-dimensional numerical simulations are conducted on the supercavitating flows (with cavitation number ranging from 0.055 to 0.315) around six planar symmetric cavitators with different streamlined headforms utilizing k – ε – v′2 – f turbulence model and Schnerr-Sauer cavitation model. We obtain the characteristics of natural supercavitation for each cavitator, including the shape and resistance characteristics and the mass transfer rate from liquid phase to vapor phase. The effects of the shape of the headform on these characteristics are analyzed. The results show that the supercavity sizes for most cavitators with streamlined headforms are smaller than that for wedge-shaped cavitator, except for the one with the profile of the forebody concaving to the inside of the cavitator. Cavitation initially occurs on the surface of the forebody for the cavitators with small curvature of the front end. Even though the pressure drag of the cavitator with streamlined headform is dramatically reduced compared with that of wedge-shaped cavitator, the pressure drag still accounts for most of the total drag. Both the drag and the mass transfer rate from liquid phase to vapor phase are in positive correlation with the supercavity size, indicating that the cavitators with the elliptic and hyperbolic cosine-type forebodies could be utilized for the optimal design of three-dimensional blade shape of RSCE.

Numerical study on gas–liquid two-phase flow and mass transfer in a microchannel

2021 ◽  
Vol 19 (3) ◽  
pp. 295-308
Author(s):  
Jin Zunlong ◽  
Liu Yonghao ◽  
Dong Rui ◽  
Wang Dingbiao ◽  
Chen Xiaotang
Keyword(s):  
Mass Transfer ◽  
Surface Tension ◽  
Slug Flow ◽  
Transfer Rate ◽  
Numerical Study ◽  
Mass Transfer Rate ◽  
Flow Patterns ◽  
Phase Flow ◽  
Two Phase ◽  
Liquid Plug

Abstract A numerical study of the gas–liquid two-phase flow and mass transfer in a square microchannel with a T-junction is carried out in this work. Through numerical simulation methods, the flow patterns of bubble flow, slug flow and annular flow are determined. By proposing a new flow pattern conversion relationship with different media and different speeds, 100 sets of CO2-water flow patterns and 100 sets of CO2-ethanol flow patterns are obtained. The effects of surface tension on flow pattern, bubble length and liquid plug length are studied. The pressure distribution and pressure drop are analyzed, and mass transfer is obtained through slug flow simulation, and the influencing factors of gas–liquid mass transfer are studied. The results show that the effect of surface tension on the length of the bubble and the length of the liquid plug is completely opposite, the pressure distribution is stepped, and the pressure drop increases with the increase of the gas–liquid velocity. In addition, it was found that the volumetric mass transfer coefficients of the bubble cap and the liquid film gradually decreased with time, and eventually stabilized. The increase in bubble velocity accelerates the mass transfer rate, while the increase in unit cell length slows the mass transfer rate. However, the influence of film thickness and liquid film length on mass transfer varies with time.

Numerical Investigation on the Effect of Tube Geometry and Feeder Height on the Heat Transfer Performance of Horizontal Tube Falling Film Evaporation

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
D. Balaji ◽  
R. Velraj ◽  
M. V. Ramana Murthy
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Film Thickness ◽  
Transfer Rate ◽  
Numerical Study ◽  
Mass Transfer Rate ◽  
Falling Film ◽  
Film Evaporation ◽  
Falling Film Evaporation ◽  
Tube Geometry

Abstract This paper discusses about the effect of tube geometry and liquid feeder height on the heat transfer performance of falling film evaporation over the horizontal heated plain tubes. To investigate this, a two-dimensional computational fluid dynamics (CFD) model was developed, compared, and validated with published data available in the literature. A numerical simulation was carried out for varying liquid load, tube diameter, liquid feeder height, and corresponding changes in the heat transfer co-efficient (HTC), and mass transfer rate was recorded and analyzed. An attempt was also made to measure the thickness of the film around the tubes from the simulation model. Mechanisms that control the factors such as HTC, film thickness, and mass transfer were numerically investigated and discussed in this work. Numerical results indicated that low value of liquid film thickness appears approximately at the angular position of the range between 90 deg and 125 deg. Also the numerical investigation revealed that liquid film thickness decreases and HTC and mass transfer rate increases with the increase of feeder height. No remarkable change in film thickness was observed with increase in the tube diameter. This numerical study also proved that the prediction of thermally developed boundary region on the circumference of the tube could be possible in terms of mass transfer rate. It was also observed from the numerical study that the highest mass transfer rate takes place between the angle 135–165 deg near to the bottom of the tube.

scholarly journals 3D flow of Carreau polymer fluid over variable thickness sheet in a suspension of microorganisms with Cattaneo-Christov heat flux

2018 ◽  
Vol 64 (5) ◽  
pp. 519 ◽  
Author(s):  
P. Durga Prasad ◽  
S. V. K. Varma ◽  
C.S.K. Raju ◽  
Sabir Ali Shehzad ◽  
M.A. Meraj
Keyword(s):  
Mass Transfer ◽  
Chemical Reaction ◽  
Variable Thickness ◽  
Heat Sink ◽  
Transfer Rate ◽  
Liquid Velocity ◽  
Numerical Study ◽  
Source Parameters ◽  
Mass Transfer Rate ◽  
Thickness Sheet

Numerical study of three dimensional Carreau liquid flow with heat and mass transport features over a variable thickness sheet filled with microorganisms is analyzed. We considered the non-uniform heat sink or source and multiple slip effects. The governing non-linear partially differential expressions are developed into ordinary differential systems by using variable transformations. These expressions are solved numerically by using Runge-Kutta fourth order method connected with shooting methodology. A Parametric study is implemented to demonstrate the effects of Hartmann number, Prandtl number, Weissenberg number, Peclet number, chemical reaction and heat sink/source parameters on liquid velocity, temperature and concentration profiles. The quantities of physical interest are described within the boundary layer. From this analysis, we found that the magnetic parameter decrease the local Sherwood and local Nusselt numbers for both and cases. The constraint of chemical reaction enhances the mass transfer rate and decelerates the density of motile mass transfer rate. The space dependent and temperature dependent heat source/sink suppress the local Nusselt number.

scholarly journals Onset of Linear and Nonlinear Thermosolutal Convection with Soret and Dufour Effects in a Porous Collector under a Uniform Magnetic Field

Fluids ◽  
2021 ◽  
Vol 6 (7) ◽  
pp. 243
Author(s):  
Redha Rebhi ◽  
Mahmoud Mamou ◽  
Noureddine Hadidi
Keyword(s):  
Magnetic Field ◽  
Mass Transfer ◽  
Transfer Rate ◽  
Numerical Study ◽  
Mass Transfer Rate ◽  
Thermosolutal Convection ◽  
Soret And Dufour Effects ◽  
Onset Of Convection ◽  
Electrically Conducting ◽  
Dufour Number

The present paper reports on an analytical and numerical study of combined Soret and Dufour effects on thermosolutal convection in a horizontal porous cavity saturated with an electrically conducting binary fluid under a magnetic field. The horizontal walls of the system are subject to vertical uniform fluxes of heat and mass, whereas the vertical walls are assumed to be adiabatic and impermeable. The main governing parameters of the problem are the Rayleigh, the Hartmann, the Soret, the Dufour and the Lewis numbers, the buoyancy ratio, the enclosure aspect ratio, and the normalized porosity of the porous medium. An asymptotic parallel flow approximation is applied to determine the onset of subcritical nonlinear convection. In addition, a linear stability analysis is performed to predict explicitly the thresholds for the onset of stationary, overstable and oscillatory convection, and the Hopf bifurcation as functions of the governing parameters. The combined effect of a magnetic field, Soret and Dufour parameters have a noticeable influence on the intensity of the convective flow, the heat and mass transfer rates, and the thresholds of linear convection. It is found that the imposition of a magnetic field delays the onset of convection and its intensification can lead to the total suppression of the convective currents. The heat transfer rate increases with the Dufour number and decreases with the Soret number and vice versa for the mass transfer rate.

Free Convective Mass Transfer at Isosceles Triangular Surfaces of Varying Inclination

2003 ◽  
Vol 68 (11) ◽  
pp. 2080-2092 ◽  
Author(s):  
Martin Keppert ◽  
Josef Krýsa ◽  
Anthony A. Wragg
Keyword(s):  
Mass Transfer ◽  
Transfer Rate ◽  
Mass Transfer Rate ◽  
Mass Transfer Process ◽  
Sulfate Solution ◽  
Convective Mass Transfer ◽  
Varying Length ◽  
Inclined Surface ◽  
Vertical Case ◽  
Limiting Diffusion Current

The limiting diffusion current technique was used for investigation of free convective mass transfer at down-pointing up-facing isosceles triangular surfaces of varying length and inclination. As the mass transfer process, copper deposition from acidified copper(II) sulfate solution was used. It was found that the mass transfer rate increases with inclination from the vertical to the horizontal position and decreases with length of inclined surface. Correlation equations for 7 angles from 0 to 90° were found. The exponent in the ShL-RaL correlation ranged from 0.247 for the vertical case, indicating laminar flow, to 0.32 for inclinations of 60 to 90°, indicating mixed or turbulent flow. The general correlation ShL = 0.358(RaL sin θ)0.30 for the RaL sin θ range from 7 × 106 to 2 × 1011 and inclination range from 15 to 90° was obtained.

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