5 research outputs found
Development And Characterization Of A Small Scale Methanol Synthesis Reactor Based On Natural Convection
No full textIncreasing renewable electricity production calls for innovative methods to store electricity as well as a desire for electrification of processes that currently rely on fossil fuels. Zero Emission Fuels is a company that is developing a system to convert carbon dioxide and water from the air into methanol, a liquid hydrocarbon fuel, using photovoltaic energy. The scale of the system is fit for a single solar PV panel. The desired methanol output is 25 grams per hour.In this work, a new design for the methanol synthesis reactor of the system is developed, built and experimentally characterized. Knowledge from work by Basarkar and Gutierrez on a previous prototype is used as the starting point. The focus of the new design is placed on the heat integration network, the natural circulation effects, and tilting of the reactor. The heat exchanger makes use of heat pipes to transfer heat. Natural circulation is increased by increasing the channel dimensions of the system. This led to an increase in mass flow rate of over 3000%, making the mass flow rate the limiting factor for reactor performance. The mass flow rate is roughly 800% higher than assumed in the design phase; the resulting energy flows are too high for the heat exchanger to work effectively. Nevertheless, the heat exchanger heating duty relative to total heating is 230% higher than Basarkar. Tilting the reactor 20 degrees reduced the mass flow rate by 46% to 0.41 g/s, improving almost all aspects of reactor performance. Productivity increased by 58% to 15.7 g/h; 182% higher than Basarkar, though the space time yield is lower (4.1 vs 6.8 mmol/gcat/h). The energy efficiency of the system is close to Basarkar at 36.5% (vs. 37.5%). It is clear from experimental correlations that reducing mass flow rate will increase productivity, energy efficiency and heat exchanger performance.By simulating the requirements for an autothermal reactor it is found that the catalyst bed dimensions should be increased in terms of diameter and length to increase to residence time in the catalyst bed. The results agree with the experimental conclusion that the mass flow rate should be reduced. Furthermore, it is recommended to heat the fluid by convection instead of conduction to ensure a more homogeneous temperature profile in the catalyst bed. Also, the heat exchanger should be expanded by adding more heat pipes and increasing the heat transfer surface area.Mechanical Engineering | Energy and Process Technolog
Experimental Characterization of a Novel Small-Scale Natural Circulation Loop Methanol Synthesis Reactor
No full textThe present-day industrialized nations reached high standards of living using cheap fossil fuel energy. The high CO2 emissions as a result of burning these fuels over the years have started outpacing the natural carbon cycle, resulting in climate changes around the globe. We have reached a point in our history where merely reducing our carbon emissions would not solve the problem, rather carbon has to be captured from the atmosphere and either stored or converted to fuels. Converting the captured CO2 into methanol has been gaining traction in recent years as it is not only an excellent fuel but also serves as the building block to manufacture other important chemicals like dimethyl ether (DME), paraffin, olefins, plastics and polymers.This thesis focusses on the complete experimental characterization of a small scale, energy efficient methanol synthesis reactor modelled on the concept developed by Wim Brilman of the University of Twente, with respect to feed flow rates, methanol production and overall efficiency. The problem of comparative energy inefficiency of the Brilman reactor was solved by carrying out the reactions in a novel, natural circulation loop (NCL) fixed packed bed reactor with internal heat recovery using Cu/ZnO/Al2O3 as the catalyst. A mixture of H2 and CO2 in the molar ratio of 3:1-the optimum ratio for methanol production was fed into the reactor. A sensitivity analysis was carried out with regards to the sampling time of the liquids at the outlet and the reaction temperature. Maximum methanol productivity of 6.8 mmole (millimoles) CH3OH/gcat/h was obtained at 228 °C reactor wall temperature and 62 °C condenser wall temperature using 5 mm diameter pellets compared to 4.3 mmole CH3OH/gcat/h obtained by Brilman at 210 °C reaction temperature and 85 °C condenser temperature. Also, a high carbon conversion of 99.2% and methanol selectivity of 99.0% was achieved. The energy demand (in MJ/kgCH3OH) was reduced from 75 in the Brilman reactor to 24 using the current design. From these results, it was established that methanol could be synthesized using a small, lab-scale reactor in an energy efficient manner.It was further observed that reduced size of the catalyst did not contribute much to methanol yield due to the high-pressure drop. Finally, a brief analysis of the heat losses in the system led to the conclusion that an additional 14.6 W of heat would have enabled autothermal operation.
Effect of Homa organic farming on growth, yield and quality parameters of Okra
No full textA field experiment was conducted during kharif season of 2012 to study the biochemical efficacy of Homa organic farming practices in okra (Abelomoschus esculentus var. Arka Anamika) and laid out in randomized block design with 18 treatments replicated thrice. The treatments consist of control treatments i.e. conventional control and homa control; homa treatments (Agnihotra and Om Tryambakam homa) and non-homa treatments; and liquid organic manures viz, Panchagavya, Jeevamruta and Gloria Biosol for soil and foliar application. Among the control treatments, organic control recorded highest growth, yield and quality parameters than other controls. Soil and foliar application of Gloria Biosol was significantly superior over all the treatments in terms of growth, yield and quality attributes and recorded 20.28% more plant height and 21.41% more yield than organic control treatments. Ascorbic acid and free total phenol content of okra fruits in homa treatments were also significantly superior over all the treat-ments and recorded 15.45% and 5.33% more over organic control, respectively. Thus, it may be recommended that soil and foliar application of Gloria Biosol, among all the Homa organic treatments, will give the better crop produc-tivity and its produce quality
Impact of Synthetic Vitamin A and Horticulture Intervention on Vitamin A Status and Iron Status of Rural School Children
No full textEvaluation Of The Levels Of The Lignans Phyllanthin, Hypophyllanthin And Niranthin In "quebra-pedra" (phyllanthus Amarus Schumach. & Thonn.) Under Water Deficit Condition [avaliação Dos Teores Das Lignanas Filantina, Hipofilantina E Nirantina Em Quebra-pedra (phyllanthus Amarus Schumach. & Thonn.), Sob Condições De Deficiência Hídrica]
No full textPhyllanthus amarus is widely used in the treatment of several diseases, especially hepatitis B, and presents in its constitution lignans of pharmacologic interest, mainly phyllanthin, hypophyllanthin and niranthin. Different environmental conditions can affect the plant chemical constitution and interfere with the levels of those substances. The aim of this study was to evaluate the water deficit (WD) influence on phyllanthin, hypophyllanthin and niranthin production in two Phyllanthus amarus accesses grown in pots kept in a greenhouse from Piracicaba County, São Paulo State, Brazil. Five treatments were tested: field capacity, besides 3, 6, 9, and 12 days without irrigation. Plant height, lipid peroxidation, and soil moisture level and active principle content through GC-MS were assessed in all treatments. WD led to a decrease in plant height in both evaluated accesses. Water availability (moisture based on weight) reduced from 100% in field capacity to 2% at 12 days, which led to a height decrease of 22% in access 14 and of 1.3% in access 7. Lipid peroxidation was significant in plants from the third day of water deficit - moderate between 3 and 6 days and more severe from the ninth day. As regards lignan levels under WD, access 14 had increases of 140% phyllanthin, 118% niranthin and 40% hypophyllanthin, whereas in access 7 these increases were less significant and occurred under moderate WD. 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