Experimental Study on the Penetration of Diesel and Biodiesel Spray Liquid Emerging from an Equilateral Triangular Orifice under Evaporative Conditions

This paper reports the results of an experimental study on the liquid phase characteristics of the biodiesel and diesel discharged from an equilateral triangular orifice and a circular orifice under different injection conditions by Mie-scattering imaging.The results revealed that the biodiesel liquid penetration length was longer than that of diesel under the same injection conditions.In addition,the increase of the chamber pressure was expected to enhance the interaction between air and fuel,resulting in the acceleration of the liquid phase breakup process.Moreover,with increasing chamber temperature,the liquid penetration of biodiesel was reduced less than that of diesel.This was due to the high surface tension and viscosity of biodiesel which inhibited the chamber air entrainment and suppressed the liquid breakup process.Accordingly,the higher probability of shorter diesel liquid penetration length indicated better air-fuel mixing than that of biodiesel.Besides,the triangular orifice liquid length was shorter than that of the circular orifice.And the stabilized liquid cone angle from the circular orifice was larger than that from the triangular orifice,indicating that using an equilateral triangular orifice has the potential to improve the air-fuel mixing process.

Three-dimensional simulation of liquid injection,film formation and transport,in fluidized beds

Liquid injection, and film formation and transport in dense-phase gas-solids fluidized beds are numerically simulated in three dimensions using a collisional exchange model that is based on the mechanism that collisions cause transfer of liquid mass, momentum, and energy between particles. In the model, each of the particles is represented by a solid core and a liquid film surrounding the core. The model is incorporated in the framework of the commercial code Barracuda developed by CPFD Software. The commercial software is an advanced CFD-based computational tool where the particles are treated as discrete entities, calculated by the MP-PIC method, and tracked using the Lagrangian method. Details of the collisional liquid transfer model have been previously presented in O＇Rourke, Zhao, and Snider （2009）; this paper presents new capabilities and proof-testing of the collision model and a new method to better quantify the penetration length. Example calculations of a fluidized bed without liquid injection show the expected effect of collisions on the reduction of granular temperature （fluctuational kinetic energy） of the bed. When applied to liquid injection into a dense-phase fluidized bed under different conditions, the model predicts liquid penetration lengths comparable to the experiments. In addition, the simulation reveals for the first time the dynamic mixing of the liquid droplets with the bed particles and the transient distribution of the droplets inside the bed.