Cowl Length Variation on Performance Characteristics of a Single Expansion Ramp Nozzle

Experiments have been carried out to investigate the effect of cowl length variation on performance characteristics of a single expansion ramp nozzle. The performance parameters were estimated for cowl lengths of 0, 25, 50, 75, and 100% with respect to the horizontal length of the ramp. Experiments were conducted for different nozzle pressure ratios ranging between 1.5 and 9. The wall static pressure distribution data were measured from the tests to estimate the various performance parameters, such as axial thrust, normal force, gross thrust, thrust vectoring angle, and coefficient of pitching moment. High-speed schlieren imaging was used to visualize the flow separation and shock patterns and to measure the jet width. The flow was separated from the ramp wall up to a nozzle pressure ratio of 3 for all cowl cases. The shorter cowl length delays the downstream movement of shock-induced boundary separation inside the nozzle as compared to the longer cowl. The cowl trailing-edge flow was more underexpanded than the ramp tip flow. As cowl length increases, the increased restriction results in higher axial thrust and also increases the normal force. The pitching moment and thrust vectoring were dominated by normal force. Overall, as the nozzle pressure ratio increases, the axial force and jet width increase, whereas the normal force and the pitching moment increase up to a certain level and then decrease. As the cowl length increases, the axial thrust, normal thrust, pitching moment, and thrust vector angle increase, while the jet width decreases

Pyrolysis and Gasification Characteristics of High Ash Indian and Turkish Coals

Pyrolysis and gasification studies of Indian and Turkish high ash coal samples have been performed using coupled TGA-MS method. Coal samples were heated in the TGA apparatus in an argon, steam, CO2 and blended mixtures of CO2 and steam in a temperature range from 25-1250°C with heating rates from 35 to 1000 K/min. Gas evolution measurements is performed using the mass spectrometry system. During the devolatilisation stage (350-700°C), the maximum mass loss has observed in which O2, CO2, CO, H2 and small amount of hydrocarbon compounds are released. Char gasification is mainly influenced by operating conditions such as heating rate and reaction temperature and also the char production method, its physical structure and size and chemical composition of the char. The steam and CO2 gasification rates of the chars are carried out at the temperatures of 850, 900, 950, and 1000°C. Three kinetic models are applied to describe the char conversion rates: volumetric model, grain model, and random pore model. The activation energy of Indian coal-char is varying from 122 to 177 kJ mol-1 under steam gasification and from 130 to 214 kJ mol-1 for CO2 gasification. The activation energy for char-steam gasification is 156-173 kJ/mol, whereas in the steam blended with CO2 gasification, it ranges between 162 and 196 kJ/mol for 3 mm particles. Similar trends are observed for the Arrhenius constant values for both sized particles

Optimizing Lithium-Ion Battery Thermal Management using CFD and Nano-Cooling

This study discusses the airflow for lithium-ion batteries during the charging process. The methodologies are designed for deployment on an inexpensive Battery Thermal Management System (BTMS). Hence, three separate phase model-based approaches for SOC estimation have been proposed and established, encompassing LIB modeling and identification techniques. This paper also examines the power intensity of a lithium-ion battery by combining and individual with the aforementioned methodologies to achieve better results. This research utilizes Computational Fluid Dynamics (CFD) to model and analyze fluid flow and heat transfer within lithium-ion batteries. It also explores the use of Phase Change Materials (PCMs) to enhance thermal management by regulating temperature through phase transitions. Together, CFD and PCMs aim to improve battery performance and safety. The best cooling efficiency was found to be achieved with a dielectric fluid, AL2O3 Nano fluid cooling system, and PCM nanofluid mixture. The battery reached 35 °C during the experimental cooling process and 34 °C during the simulation. The dielectric fluid with AL2O3 nano fluid cooling system and PCM reached a maximum temperature of 45 °C, while forced air and dielectric cooling reached maximums of 46 °C and 46 °C, respectively. The results are based on modern cooling efficiency techniques such as Phase Change Material (PCM) and Nano cooling fluids

Glycerol conversion to 1, 3-Propanediol is enhanced by the expression of a heterologous alcohol dehydrogenase gene in Lactobacillus reuteri

In this work, Lactobacillus reuteri has been metabolically engineered for improving 1, 3-propanediol (1, 3-PD) production by the expression of an Escherichia coli alcohol dehydrogenase, yqhD, that is known to efficiently convert the precursor 3-hydroxypropionaldehyde (3-HPA) to 1, 3-PD. The engineered strain exhibited significantly altered formation rates for the product and other metabolites during the fermentation. An increase in the 1, 3-PD specific productivity of 34% and molar yield by 13% was achieved in the clone, relative to the native strain. A concomitant decrease in the levels of toxic intermediate, 3-HPA, was observed, with the specific productivity levels being 25% lesser than that of the native strain. Interestingly, the recombinant strain exhibited elevated rates of lactate and ethanol formation as well as reduced rate of acetate production, compared to the native strain. The preferential utilization of NADPH by YqhD with a possible decrease in the native 1, 3-PD oxidoreductase (NADH-dependent) activity, could have resulted in the diversion of surplus NADH towards increased lactate and ethanol productivities

Effect of char generation method on steam, CO2 and blended mixture gasification of high ash Turkish coals

AbstractChar particles of high ash Turkish coal of two sizes were produced by pyrolysis in an atmospheric pressure thermo-gravimetric apparatus using 3 heating rates (100K/min, 500K/min and 800K/min). It is observed that the particle size (for particles between 0.8 and 3mm) did not change the pyrolysis process results. Char gasification rates in CO2, steam and mixture of CO2+steam are investigated in the same TGA system over the temperature range of 850–950°C. The pyrolysis heating rate for char formation is observed to have a marked influence on the subsequent gasification reactivity of the char. The results indicate that the char produced from high heating rates show improved gasification rates. Smaller particles exhibit higher char–CO2 and char–steam gasification rates. Increasing the temperature from 850 to 950°C, leads to a significant reduction of the time required for 50% char conversion both for small and large particles. The maximum reaction rate is shifted to higher conversion degrees when the chars are produced from high heating rates. The gasification rate of char–H2O strongly depends on the H2O partial pressure. Gasification rates in CO2 ambiance are much lower than those in steam. For CO2–steam blended ambiance, no obvious CO2 inhibition effect is observed. But this topic requires more investigation. Kinetic parameters of the char particles are estimated using three different kinetic models. The obtained activation energies for char gasification essentially depend on the particle size and the three kinetic models give very close activation energy values for all the tested conditions