scholarly journals Supercritical CO2 Extraction of Extracted Oil from Pistacia lentiscus L.: Mathematical Modeling, Economic Evaluation and Scale-Up

Molecules ◽  
2020 ◽  
Vol 25 (1) ◽  
pp. 199 ◽  
Author(s):  
Abdelkarim Aydi ◽  
André Wüst Zibetti ◽  
Abdulaal Z. Al-Khazaal ◽  
Aboulbaba ELADEB ◽  
Manef ADBERRABA ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Intact Cell ◽  
Scale Up ◽  
Extraction Yield ◽  
Point Of View ◽  
Significant Variable ◽  
Pistacia Lentiscus ◽  
Economic Point ◽  
Transfer Parameter ◽  
Mass Transfer Parameter

In this study, the extracted oil of Pistacia lentiscus L. the Tunis region was extracted using supercritical carbon dioxide (SC-CO2) extraction containing different major components in the oil such as α-pinene (32%) and terpinene-4-ol (13%). The investigation of the effect of different variables on the extraction yield with 5% level of confidence interval showed that the CO2 pressure was the main significant variable to influence the oil yield. In order to better understand the phenomena, three parameters were considered to adjust all parameters of broken and intact cell (BIC) model: grinding efficiency (G), the internal mass transfer parameter ( k S a 0 ), and the external mass transfer parameter ( k f a 0 ), which were estimated by experimental extraction curves to calculate the diffusion coefficient. From an economic point of view, we found out that the high cost of production of the extracted oil was due to the low mass of extracted oil obtained from this type of plant.

DECISION PRINCIPLES FOR ASCENT SUPPORTS IN BUILDING CONSTRUCTION

2014 ◽  
Vol 1 (1) ◽  
Author(s):  
Dieter Schlagbauer ◽  
Christian Hofstadler ◽  
Cornelia Ninaus
Keyword(s):  
Empirical Studies ◽  
Economic Value ◽  
Scale Up ◽  
Point Of View ◽  
Construction Sites ◽  
Economic Point ◽  
Current State ◽  
Frequency Of Use ◽  
A Site ◽  
Economic Comparison

Ladders are the ascent system most commonly used to scale up a building, due to the low initial costs compared to other ascent equipment. The insufficiency of this approach is shown in an economic comparison of ladders, stair towers, and scaffoldings with integrated ascent support. Based on empirical studies, cost data and the current state of scientific knowledge, the ascent support with the highest economic value can be determined by considering safety, cost, time, stress, physical stress and strain, and frequency of use. A survey evaluated vertical transport routes, the ascent systems ladders, stair towers, and scaffoldings with integrated ladders. The findings indicate that from an economic point of view, ladders should be used only on construction sites where less than 54 ascents were performed each day. This leads to the assumption that for typical construction sites, with at least 6 ascents per person per day and a site usage for a period longer than one week, the operation of ladders is uneconomical.

Continuous thermal hydrolysis and anaerobic digestion of sludge. Energy integration study

2012 ◽  
Vol 65 (10) ◽  
pp. 1839-1846 ◽  
Author(s):  
S. I. Pérez-Elvira ◽  
F. Fdz-Polanco
Keyword(s):  
Anaerobic Digestion ◽  
Residence Time ◽  
Pilot Plant ◽  
Scale Up ◽  
Green Energy ◽  
Point Of View ◽  
Thermal Hydrolysis ◽  
Economic Point ◽  
Gas Engine ◽  
Secondary Sludge

Experimental data obtained from the operation in a pilot plant are used to perform mass and energy balances to a global process combining units of thermal hydrolysis (TH) of secondary sludge, anaerobic digestion (AD) of hydrolysed secondary sludge together with fresh primary sludge, and cogeneration from biogas by using a gas engine in which the biogas produces electricity and heat from the exhaust gases. Three scenarios were compared, corresponding to the three digesters operated: C (conventional AD, 17 days residence time), B (combined TH + AD, same time), and A (TH + AD at half residence time). The biogas production of digesters B and A was 33 and 24% better, respectively when compared with C. In the case of the combined TH + AD process (scenarios A and B), the key factors in the energy balance were the recovery of heat from hot streams, and the concentration of sludge. The results of the balances showed that for 8% DS concentration of the secondary sludge tested in the pilot plant, the process can be energetically self-sufficient, but a fraction of the biogas must by-pass the gas engine to be directly burned. From an economic point of view, scenario B is more profitable in terms of green energy and higher waste removal, while scenario A reduces the digester volume required by a half. Considering a population of 100,000 inhabitants, the economic benefit is 87,600 €/yr for scenario A and 132,373 €/yr for B. This value can be increased to 223,867 €/yr by increasing the sludge concentration of the feeding to the TH unit to a minimum value that allows use of all the biogas to produce green energy. This concentration is 13% DS, which is still possible from a practical point of view. Additional benefits gained with the combined TH + AD process are the enhancement of the digesters rheology and the possibility of getting Class A biosolids. The integration study presented here set the basis for the scale-up to a demonstration plant.

scholarly journals Thermal Diffusion and Diffusion Thermo Effects on the Viscous Fluid Flow with Heat and Mass Transfer through Porous Medium over a Shrinking Sheet

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Nabil Eldabe ◽  
Mahmoud Abu Zeid
Keyword(s):  
Mass Transfer ◽  
Porous Medium ◽  
Shear Stress ◽  
Differential Equations ◽  
Heat And Mass Transfer ◽  
Shrinking Sheet ◽  
Physical Parameters ◽  
Transfer Parameter ◽  
Mass Transfer Parameter ◽  
Permeability Parameter

The motion of the viscous, incompressible fluid through a porous medium with heat and mass transfer over a shrinking sheet is investigated. The cross-diffusion effect between temperature and concentration is considered. This phenomenon is modulated mathematically by a set of partial differential equations which govern the continuity, momentum, heat, and mass. These equations are transformed to a set of ordinary differential equations by using similarity solutions. The analytical solutions of these equations are obtained. The velocity, temperature, and concentration of the fluid as well as the heat and mass transfer with shear stress at the sheet are obtained as a function of the physical parameters of the problem. The effects of Prandtl number, mass transfer parameter, the wall shrinking parameter, the permeability parameter, and Dufour and Soret numbers on temperature and concentration are studied. Also, the effects of mass transfer parameter, permeability parameter, and shrinking strength on the velocity and shear stress are discussed. These effects are illustrated graphically through a set of figures.

Effect of Biological and Mass Transfer Parameter Uncertainty on N2O Emission Estimates from WRRFs

2017 ◽  
Vol 89 (7) ◽  
pp. 580-585 ◽  
Author(s):  
Kang Song ◽  
Willie F. Harper ◽  
Yuki Takeuchi ◽  
Masaaki Hosomi ◽  
Akihiko Terada
Keyword(s):  
Mass Transfer ◽  
Parameter Uncertainty ◽  
N2o Emission ◽  
Transfer Parameter ◽  
Mass Transfer Parameter

Sophie Laws, with Caroline Harper and Rachel Marcus. Research for Development: A Practical Guide. New Delhi: Vistaar Publications. 2003. xiii+475 pages. Paperback. Indian Rupees 450.00.

2003 ◽  
Vol 42 (2) ◽  
pp. 170-172
Author(s):  
Mir Annice Mahmood
Keyword(s):  
Policy Research ◽  
Point Of View ◽  
Basic Question ◽  
New Delhi ◽  
Economic Point ◽  
Scarce Resources ◽  
Is Research ◽  
The Subject ◽  
Development Workers

To implement any successful policy, research about the subject-matter is essential. Lack of knowledge would result in failure and, from an economic point of view, it would lead to a waste of scarce resources. The book under review is essentially a manual which highlights the use of research for development. The book is divided into two parts. Part One informs the reader about concepts and some theory, and Part Two deals with the issue of undertaking research for development. Both parts have 11 chapters each. Chapter 1 asks the basic question: Is research important in development work? The answer is that it is. Research has many dimensions: from the basic asking of questions to the more sophisticated broad-based analysis of policy issues. The chapter, in short, stresses the usefulness of research which development workers ignore at their own peril.

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