Saurabh Sharma

Effects of Fuel Unsaturation on Transient Ignition and Flame Development in Sprays

ABSTRACT Fundamental studies using homogeneous mixtures in shock tube and rapid compression machine (RCM) have shown that the fuel reactivity and ignition characteristics are significantly affected by the presence and number of double bonds in the fuel molecular structure. However, this phenomenon has not been investigated in turbulent reacting sprays under realistic conditions. In this article, we numerically examine the effects of fuel unsaturation and sensitivity on the transient ignition and flame evolution in n-heptane and 1-heptene sprays in the Sandia constant volume reactor. 3D simulations of two-phase reacting flows are performed using a commercial CFD code, CONVERGE. The ignition and combustion chemistry of n-heptane and 1-heptene is modeled using a reduced CRECK mechanism, which has been previously validated against the shock tube ignition delays and reacting spray measurements. Results indicate that, at intermediate temperatures, the ignition in both homogeneous mixtures and sprays is strongly influenced by fuel unsaturation. First of all, the ignition delay is much higher for 1-heptene compared to that for n-heptane, especially at low temperatures. Secondly, ignition in n-heptane sprays occurs in fuel rich mixtures, and is characterized by a two-stage ignition process. On the other hand, ignition in 1-heptene sprays occurs in lean mixtures. Results also indicate the existence of multiple ignition locations in sprays, which is in contrast to ignition in homogeneous mixtures. The flame evolution in sprays correlates strongly with the ignition kernel evolution. Consequently, the n-heptane spray flame contains two reaction zones, namely, a rich premixed zone (RPZ) and a non-premixed reaction zone (NPZ), while the 1-heptene flame is characterized by three reaction zones, i.e., a lean premixed zone in addition to NPZ and RPZ. The difference is a direct consequence of longer ignition delay in 1-heptene spray compared to that in n-heptane spray, which facilitates increased fuel-air mixing in the former. The flame lift-off location correlates with the ignition delay and ignition kernel location. Thus, at lower temperatures (1000 K and 1100 K), the lift-off length of 1-heptene flame is greater than that of n-heptane flame, which is due to longer ignition delays for 1-heptene sprays. In contrast, at higher temperatures (1200 K) the lift-off length of 1-heptene flame is smaller, which is due to the fact that the ignition kernel and, thus, lean premixed zone are located closer to the injector for 1-heptene spray compared to n-heptane spray.

Quantification of Factor Productivity in Pigeon PEA Through Front Line Demonstration

The study was carried out in Sehore district of Madhaya Pradesh by conducting front line demonstrations on pigeon pea in different locations of farmers’ field to promote the cultivation and adoption of improved package of practices. The seeds of improved varieties and balanced fertilizers were the part of technological package supplied to the demonstration plot as against control. All the demonstrations were conducted by following participatory approach. The results revealed that improved varieties and balanced fertilization increased the yield to the tune of 13.36 percent and 42.26 per cent, respectively while both the factors in combination were responsible for 10.93 per cent increase in yield. In demonstration plots C: B ratio was also higher as compared to the control ones. It was concluded that while selecting the inputs during the scarcity or abundanceness of inputs improved varieties must be given priority as they alone foster higher amount of increase in yield.

Impact Assessment of Oilseed F Based Front Line Demonstration on Rapeseed and Mustard

The present study was carried out in Sehore district of Madhya Pradesh by Krishi Vigyan Kendra, Sehore. Total numbers of 81 front line demonstrations on mustard crop were conducted in different locations at farmers ’field to promote the cultivation and increase the adoption of improved package of practice. The seeds of improved varieties with seed treatment and use of rizhobium culture, and balanced fertilizers were the part of technological components supplied to the demonstration plot as against control. All the demonstrations were carried out in close coordination of scientist and farmers as well. Results revealed that improved varieties and balanced fertilization increased yield to the tune of 6.2% and 9.6%, respectively. While both the factors in combination were contributing 15.8% increase in yield. In demonstration plots C: B ratio was also obtained in demonstration fields was also higher as compared to control ones. It was suggested that while selecting the inputs for mustard balance fertilization (N: P: K 100: 80: 40) with additional supply of sulphur @ 30 Kg/ha should be given priority.