A Comparison of Co-Current and Counter-Current Modes of Operation in Urea Prilling Tower

2014 ◽  
Vol 917 ◽  
pp. 199-208 ◽  
Author(s):  
Nejat Rahmanian ◽  
Marjan Homayoonfard
Keyword(s):  
Heat Transfer Performance ◽  
Present Model ◽  
Control Strategies ◽  
Moisture Distribution ◽  
Current Scenario ◽  
Current Operation ◽  
Cooling Air ◽  
Counter Current ◽  
Model Temperature ◽  
Urea Prills

In this paper, a model for urea prilling tower with co-current flow of cooling air and urea prills (particles) is presented. The process is modelled by simultaneous solution of the differential equations for hydrodynamics, heat and mass transfer between the air and prills. The process variables such as temperature, absolute and relative humidity of air along the height of the tower were obtained from this model. Temperature and moisture distribution of urea prills and their radial and vertical velocities were also calculated. The results of the present model were compared with the counter-current operation model available in the literature. The simulation results show that heat transfer performance for co-current operation is significantly less than that of the counter-current scenario. This is more pronounced for small prills, i.e. 1.0 mm than that of the large prills. The advantage of the model is that it can be used to investigate influence of operating parameters on efficiency of the co-current process. This also helps us to set the process control strategies for design and quality control purposes of the process.

An Insight into Nanomedicinal Approaches to Combat Viral Zoonoses

2020 ◽  
Vol 20 (11) ◽  
pp. 915-962
Author(s):  
Prasad Minakshi ◽  
Mayukh Ghosh ◽  
Rajesh Kumar ◽  
Basanti Brar ◽  
Upendra P. Lambe ◽  
...  
Keyword(s):  
Control Strategies ◽  
Delivery Systems ◽  
Viral Diseases ◽  
Bibliographic Databases ◽  
Health Concept ◽  
Current Scenario ◽  
Potential Benefits ◽  
Successful Control ◽  
The One ◽  
And Control

Background: Emerging viral zoonotic diseases are one of the major obstacles to secure the “One Health” concept under the current scenario. Current prophylactic, diagnostic and therapeutic approaches often associated with certain limitations and thus proved to be insufficient for customizing rapid and efficient combating strategy against the highly transmissible pathogenic infectious agents leading to the disastrous socio-economic outcome. Moreover, most of the viral zoonoses originate from the wildlife and poor knowledge about the global virome database renders it difficult to predict future outbreaks. Thus, alternative management strategy in terms of improved prophylactic vaccines and their delivery systems; rapid and efficient diagnostics and effective targeted therapeutics are the need of the hour. Methods: Structured literature search has been performed with specific keywords in bibliographic databases for the accumulation of information regarding current nanomedicine interventions along with standard books for basic virology inputs. Results: Multi-arrayed applications of nanomedicine have proved to be an effective alternative in all the aspects regarding the prevention, diagnosis, and control of zoonotic viral diseases. The current review is focused to outline the applications of nanomaterials as anti-viral vaccines or vaccine/drug delivery systems, diagnostics and directly acting therapeutic agents in combating the important zoonotic viral diseases in the recent scenario along with their potential benefits, challenges and prospects to design successful control strategies. Conclusions: This review provides significant introspection towards the multi-arrayed applications of nanomedicine to combat several important zoonotic viral diseases.

Counter-current operation of a structured catalytically packed-bed reactor:

1999 ◽  
Vol 54 (21) ◽  
pp. 5145-5152 ◽  
Author(s):  
A.P. Higler ◽  
R. Krishna ◽  
J. Ellenberger ◽  
R. Taylor
Keyword(s):  
Packed Bed ◽  
Packed Bed Reactor ◽  
Current Operation ◽  
Counter Current

scholarly journals Epidemiology and control strategies of novel coronavirus disease in the context of India

2021 ◽  
Vol 13 (1) ◽  
pp. 210-219
Author(s):  
Abhishek Gupta ◽  
Alka Rani ◽  
Nisha Sogan ◽  
R. S. Sharma ◽  
Bindu Sharma
Keyword(s):  
Control Strategies ◽  
Morbidity And Mortality ◽  
Successful Implementation ◽  
High Morbidity ◽  
Frontline Workers ◽  
Current Scenario ◽  
Proper Diagnosis ◽  
Novel Coronavirus ◽  
And Control ◽  
First Time

An outbreak of coronavirus disease (COVID-19) occurred for the first time in Wuhan, China which spread as a pandemic to various countries of the world, resulting in high morbidity and mortality. Death toll in India on 8th February 2021 was 1,55,080. India had implemented steps such as lockdown and advised social distancing, washing of hands, and wearing masks to reduce the burden of Covid-19. This review discusses the epidemiological features, the population at risk and control strategies of novel coronavirus disease in India. The data was collected from various sources on individual details of Covid-19 cases, population density and affluence percentage from the literature studied. The data was used to analyse the susceptibility of the population to this disease. It was found that Indian males, age group 20 to 40 (based on morbidity) and above 60 (based on mortality) were at high risk. The authors compiled epidemiology, management and control strategies of covid-19 in India. Therefore, because of various early implementations, India has managed the disease well earlier, but in the current scenario (30 Nov 2020) morbidity and mortality have been at peak. Immunization of frontline workers started on 16th January 2021. Initially, 7,017,411 doses of Covishield and Covaxin vaccines have been given by 10th February 2021. Thus, the existing strategies like proper diagnosis, treatment, and successful implementation of vaccine inoculation will reduce covid-19 burden and may lead to normalcy.

scholarly journals Simulation Study on Direct Contact Membrane Distillation Modules for High-Concentration NaCl Solution

Membranes ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 179
Author(s):  
Weiming Ni ◽  
Yongli Li ◽  
Juezhen Zhao ◽  
Gaoyuan Zhang ◽  
Xiaoze Du ◽  
...  
Keyword(s):  
Membrane Distillation ◽  
Membrane Thickness ◽  
Permeate Flux ◽  
Nacl Solution ◽  
High Concentration ◽  
Feed Velocity ◽  
Temperature Polarization ◽  
Current Operation ◽  
Counter Current ◽  
Feed Temperature

Membrane distillation technology, as a new membrane-based water treatment technology that combines the membrane technology and evaporation process, has the advantages of using low-grade heat, working at atmospheric pressure with simple configuration, etc. In this study, heat and mass transfer were coupled at the membrane surfaces through the user-defined function program. The effects of feed temperature, feed velocity and permeate velocity on temperature polarization were mainly investigated for a high-concentration NaCl solution. The temperature polarization was increased with the increase of feed temperature and the decrease of feed and permeate velocity. The effects of temperature, inlet velocity and solution concentration on the evaporation efficiency of the membrane module for co- and counter-current operations were investigated in detail. The counter-current operation performed better than co-current operation in most cases, except for the condition where the NaCl concentration was relatively low or the module length was long enough. In addition, the optimal membrane thickness for both PVDF and PTFE was studied. The optimal membrane thickness was found in the range of 10 to 20 μm, which corresponded to the highest permeate flux for the selected materials, pore size distribution, and operation conditions. Membrane material with lower thermal conductivity and larger porosity was prone to get higher permeate flux and had larger optimal membrane thickness. Increasing feed velocity or feed temperature could decrease the optimal membrane thickness.

Numerical Simulation of Spray Cooling Pond Performance

1987 ◽  
Vol 109 (2) ◽  
pp. 179-185 ◽  
Author(s):  
N. Moussiopoulos
Keyword(s):  
Mathematical Model ◽  
Differential Equations ◽  
Present Model ◽  
Field Measurements ◽  
Equation System ◽  
Spray Cooling ◽  
Cooling Pond ◽  
Dependent Variables ◽  
Model Temperature ◽  
Good Agreement

A mathematical model for predictions of the performance of spray cooling ponds is presented. In contrast to previous methods, the present model requires neither empirical information from field measurements nor an adaptation of model constants. The airflow is described by partial differential equations for the vorticity and the stream function. Turbulence is taken into account by a modified version of the k-ε model. Temperature and humidity of air are obtained by solving appropriate transport differential equations. The equation system is solved by means of a finite difference method. The utilized numerical algorithm has been proved to be reasonably accurate. Predicted distributions for the dependent variables are presented for a circular spray cooling pond and the case of zero wind velocity. Results for the thermal performance of this pond are in good agreement with observations.

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