02255nas a2200241   4500008004100000022001400041245005300055210005300108260006900161300001200230490000800242520148400250653002201734653003301756653002101789100002401810700001701834700001901851700001801870700001601888700002201904856008701926       2012                        eng d  a1385-894700aModeling of liquid propellant combustion chamber0 aModeling of liquid propellant combustion chamber  aPO BOX 564, 1001 LAUSANNE, SWITZERLANDbELSEVIER SCIENCE SAcOCT  a151-1660 v2073 a<p>Liquid propellants are fuels which do not require external supply of oxygen for combustion. These fuels are widely used for propulsion applications in oxygen rare environments (underwater, space). We had previously presented a model for solid propellant decomposition in a combustion chamber. In this study we extend the model for the case of combined solid and liquid propellant combustion. Sub-models relating to solid propellant combustion and outlet flow-rate in the present study are borrowed from the previous study. The combustion chamber is assumed to be a `well-mixed reactor'. A model is developed to characterize the liquid propellant spray assuming the spray is a collection of individually burning droplets. A single droplet decomposition model was developed and used along-with the spray model to solve for the liquid propellant burning rate. Appropriate numerical methods and computer programs were developed to solve the model equations. The model predictions were compared with the experimental data obtained in earlier studies. Appropriate methodology for calibrating the model parameters was developed and its usefulness was demonstrated by comparing the simulated pressure profiles with the experimental pressure profiles. The presented model and results will be useful for selecting appropriate liquid propellants for propulsion systems and for the development of a system level model of propulsion systems. (C) 2012 Elsevier B.V. All rights reserved.</p>10aLiquid propellant10aSingle droplet decomposition10aSpray combustion1 aPandit, Ajinkya, V.1 aKumar, Ashok1 aRao, Srinivasa1 aKedarnath, C.1 aSrihari, R.1 aRanade, Vivek, V.  uhttps://library.ncl.res.in/content/modeling-liquid-propellant-combustion-chamber-002910nas a2200157   4500008004100000022001400041245010800055210006900163260007100232300001600303490000700319520224800326100002402574700002202598856013202620       2015                        eng d  a0888-588500aModeling hysteresis during crystallization and dissolution: application to a paracetamol-ethanol system0 aModeling hysteresis during crystallization and dissolution appli  a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcOCT  a10364-103820 v543 a<p>Crystallization and dissolution processes are of great scientific and commercial interest. Significant efforts have been made in the past to develop mathematical models to describe these processes. In this work, observed hysteresis in particle counts during the crystallization and dissolution processes was used to develop and to test the mathematical models of crystallization and dissolution. Crystallization and dissolution experiments were performed with a system of paracetamol and ethanol. An undersaturated solution was first cooled at a particular rate causing crystallization and crystal growth. The solution was then reheated at the same rate to completely dissolve the generated particles. The particle counts and particle size distribution were measured online using a focus beam reflectance measurement (FBRM) probe. A hysteresis was observed in particle counts with respect to the solution temperature. It was also observed that this hysteresis was affected by the applied heating/cooling rates (0.3, 0.5, and 0.7 K/min) for of the solution. A systematic modeling framework based on the population balance equation (PBE) is developed for quantitatively capturing this hysteresis and the influence of cooling/heating rate on the hysteresis curve. A two-level approach was developed to simulate hysteresis: (a) PBE was solved using computationally efficient method of moments for the crystallization stage. This step was used to efficiently estimate values of parameters appearing in the model equations. (b) PBEs describing crystallization and dissolution were then solved using high resolution finite volume (HRFV) scheme coupled with the moving pivot method. The simulated hysteresis curve showed good agreement with the experimental data. Though simulated results over predicted the average particle (by,similar to 131%), the models were successful in qualitatively explaining the counterintuitive trends observed as the average particle size was tracked with time. The framework was thus shown to be a reliable and robust framework to model crystallization and dissolution processes. The developed approach, models, and results will be useful for simulating industrially relevant crystallization dissolution processes.</p>1 aPandit, Ajinkya, V.1 aRanade, Vivek, V.  uhttps://library.ncl.res.in/content/modeling-hysteresis-during-crystallization-and-dissolution-application-paracetamol-ethanol-0