다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Foreword 1. Prosperity Lost 2. The Age of Irresponsibility 3. Redefining Prosperity 4. The Dilemma of Growth 5. The Myth of Decoupling 6. The 'Iron Cage' of Consumerism 7. Keynesianism and the 'Green New Deal' 8. Ecological Macro-Economics 9. Flourishing - within Limits 10. Governance for Prosperity 11. The Transition to a Sustainable Economy 12. A Lasting Prosperity Appendices References Endnotes

Prosperity without growth : economics for a finite planet

Biodiesel is produced by the transesterification of oil triglycerides with methanol or ethanol, in the presence of a homogeneous or heterogeneous catalyst. This study aims to report the results of the transesterification of sunflower oil with methanol to produce biodiesel using CaO nanoparticles supported on NaX zeolite as catalyst. The effect of the CaO nanoparticles concentration on the NaX zeolite surface was studied in the range of 5−25 wt %. The transesterification reaction was carried out at reflux temperature of methanol, atmospheric pressure, a reaction time of 6 h, and with a 6:1 molar ratio of methanol to sunflower oil. Catalyst characterization was carried out by X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. It was concluded that methyl esters content is highly influenced by basicity and that the best catalyst was the one holding 16 wt % CaO nanoparticles. The produced biodiesel was 93.5% methyl esters and was found to fulfill the specifications of Europ...

Preparation and Characterization of CaO Nanoparticles/NaX Zeolite Catalysts for the Transesterification of Sunflower Oil

The world is confronted with the twin crises of fossil fuel depletion and environmental degradation. The indiscriminate extraction and consumption of fossil fuels have led to a reduction in petroleum reserves. Petroleum based fuels are obtained from limited reserves. These finite reserves are highly concentrated in certain region of the world. Therefore, those countries not having these resources are facing a foreign exchange crisis, mainly due to the import of crude petroleum oil. Hence it is necessary to look for alternative fuels, which can be produced from materials available within the country. Although vegetative oils can be fuel for diesel engines, but their high viscosities, low volatilities and poor cold flow properties have led to the investigation of its various derivatives. Among the different possible sources, fatty acid methyl esters, known as Biodiesel fuel derived from triglycerides (vegetable oil and animal fates) by transesterification with methanol, present the promising alternative substitute to diesel fuels and have received the most attention now a day. The main advantages of using Biodiesel are its renewability, better quality exhaust gas emission, its biodegradability and the organic carbon present in it is photosynthetic in origin. It does not contribute to a rise in the level of carbon dioxide in the atmosphere and consequently to the green house effect. This paper reviews the source of production and characterization of vegetable oils and their methyl ester as the substitute of the petroleum fuel and future possibilities of Biodiesel production.

Biodiesel production through the use of different sources and characterization of oils and their esters as the substitute of diesel: A review

A techno-economic analysis was conducted to compare 3 different processes for biodiesel production: (i) the conventional base-catalysed process (NaOH) (ii) a reactive coupling process to form glyce...

Techno-economic analysis of processes for biodiesel production with integrated co-production of higher added value products from glycerol

Additive manufacturing enables the fabrication of geometries previously unavailable via conventional means. Here, a helically coiled channel containing a secondary helical coil insert was 3D-printed and operated in a net flow with superimposed oscillation. This “coil-in-coil” geometry exhibited exceptional plug flow quality at low Reynolds numbers (Re = 10–50). High levels of plug flow were observed at oscillation amplitudes of 2–8 mm. The greatest degree of plug flow occurred with Reo/Ren = 2–7 and Sr = 1–2. Surprisingly, the coil-in-coil geometry demonstrated excellent plug flow behavior (N = 40–100) at very low oscillation frequencies (f = 0.25–0.5 Hz). Compared to various benchmark designs (“plain” coiled tube, straight tube containing a helical coil insert, and plain straight tube), the coil-in-coil geometry demonstrated enhanced plug flow quality at low frequencies (≤1 Hz) at all amplitudes and low amplitudes (1–2 mm) at all frequencies.

Coil-in-Coil Reactor: Augmenting Plug Flow Performance by Combining Different Geometric Features Using 3D Printing

Oscillatory baffled reactors (OBRs) are a form of plug flow reactor that can be used for long reactions, as the plug flow is not dependent on achievement of a certain velocity in the reactor leading to much more compact designs. One class of long reactions is that of bioreactions/fermentations. Since one major advantage of the OBR is its highly uniform, controllable mixing, which can be used to enhance gas-to-liquid mass transfer, it should be suitable for biological reactions. Continuous fermentation is a second advantage, as it should minimise substrate and product inhibition. Lower, more uniform shear rates than in a stirred tank reactor would be an additional advantage for processing shear-sensitive cells. Previous research has shown that the OBR can provide higher biomass concentrations and greater gasliquid mass transfer than conventional fermenters. In this work, the production of polyhydroxyalkanoates (PHA) by Pseudomonas putida was investigated. The parameters investigated here were agitation, aeration rate and temperature. Additionally, various media were investigated to determine the effect on yield. It was demonstrated that PHA can be produced in the OBR. The optimum fermentation temperature and agitation rate for PHA production in this parameter space were determined. It was also demonstrated that using an OBR can lead to higher OD and dry cell weight than a conventional stirred tank reactor.

The Production of Polyhydroxyalkanoates using an Oscillatory Baffled Bioreactor

This study reports the evaluation of heat transfer characteristics and pressure drops in three designs of meso-scale oscillatory baffled reactors over the net flow range Re n  = 60–2500 and the oscillatory flow range Re o  = 0-1600. The three designs were the oscillatory central baffled reactor (OCBR), the oscillatory helical baffled reactor (OHBR), and the oscillatory orifice baffled reactor (OOBR). The designs were evaluated in terms of “thermal performance” to take the heat transfer and pressure drop into account. Interestingly, in all designs the pressure drop was observed to decrease with increasing oscillation, due to some degree of energy recovery. In all cases, oscillating the flow significantly enhanced the Nusselt number by upto a maximum of around 10-fold. The meso-OBRs were shown to achieve higher thermal performances than steady flows in smooth tubes in all cases. Up to 480%, 460%, and 300% improvements in thermal performance was achieved for the OHBR, OCBR, and OOBR, respectively. The OHBR exhibited the lowest pressure drop, resulting in the highest thermal performance of the designs investigated here. Hence, on the basis of this study, the OHBR design is recommended. New empirical correlations for predicting pressure drop and Nusselt number were established for each design, with data mostly lying in the range ±30% of the correlations.

/pdf/thermal-performance-of-meso-scale-oscillatory-baffled-nqqw3gv1l4.pdf

Thermal performance of meso-scale oscillatory baffled reactors

The reactor is often described as the ‘heart’ of a chemical processes. This is based on the fact that the downstream processes are a function of the reactor performance, particularly such features as degree of control, selectivity and heat and mass transfer (which are substantially interdependent). Furthermore, the upstream processes can be viewed as a set of steps whose sole purpose is to get the reactants to the correct condition for input to the reactor.

Consequently, in the field of Process Intensification, the reaction step has received more attention than other unit operations. This is illustrated by the large number of intensified reactors either on the market or under development. This chapter introduces several of the most important of these, following a short tutorial on reactor theory that puts the main characteristics of reactors in an appropriate context.

Adam Harvey

Papers

Techno-economic analysis of processes for biodiesel production with integrated co-production of higher added value products from glycerol

Coil-in-Coil Reactor: Augmenting Plug Flow Performance by Combining Different Geometric Features Using 3D Printing

The Production of Polyhydroxyalkanoates using an Oscillatory Baffled Bioreactor

Thermal performance of meso-scale oscillatory baffled reactors

Chapter 5 – Reactors