Session: 08-01: Poster Session

Paper Number: 148368

148368 - Experimental Analysis of Liquid Ammonia Spray and Combustion in a Constant Volume Combustion Chamber 

Abstract: 

Recent efforts to reduce carbon emissions have made ammonia an increasingly popular fuel for energy and transportation. But studies have strongly suggested that ammonia has difficulties in ignition and heat release when used in a gaseous form. On the other hand, working with liquid ammonia presents countless problems like difficulty in pressurizing and metering, damage to elastomers and other metals, etc. In this study, pure liquid ammonia is injected into a constant volume combustion chamber (CVCC) using a gasoline direction injection (GDI) injector. The purpose of this study is to understand the behavior of liquid ammonia when sprayed into different ambient densities using a pre-burn CVCC system. Specifically, with applications aimed towards compression ignition systems and spark assisted compression ignition systems in medium to heavy-duty engines. Pure liquid ammonia spray is characterized based on optical measurements using high speed back lit shadowgraph and Schlieren imaging. Based on the spray profile and mixing characteristics, with pure ammonia injections, both autoignition and spark assisted ignition are studied. Due to the issues surrounding the effective ignition of liquid ammonia sprays, a dual fuel operation mode is also studied to understand the effect of adding a secondary fuel pilot to promote ignition and reduce ignition delay. The CVCC is set up with 2 injectors on opposite sides, one with a multi-hole injector capable of injecting fuels like diesel, methanol, etc. as the pilot, and the other is the GDI injector capable of injecting liquid ammonia. Several parameters including the spray jet interactions, flame kernel development, flame extinction due to spray impingement, etc. are studied in detail. Moreover, the effects of spray timing modulation and phasing, pilot quantity, and injection duration on the ignition characteristics like ignition delay and initial flame kernel location are studied in detail. This is to understand the effects of fuel diffusion and jet to jet interactions on the ignition process. Additionally, injection temperature and pressure conditions encompassing the ammonia’s critical transformations are also studied. As liquid ammonia tends to rapidly vaporize and flash-boil at pressures and temperatures above 50 bar these conditions can provide a good understanding of the potential control over mixing. This study has novel contribution to the development of direct injection of liquid ammonia spray for applications in high-power density engine systems.

Presenting Author: Tiegang Fang North Carolina State University

Presenting Author Biography: Dr. Fang’s research goal is to improve the environment and reduce our energy needs by the advancement of clean combustion. He is interested in combustion, internal combustion engines, exhaust emissions and air pollution control, alternative fuels, spray and atomization, droplet impact, laser diagnostics for reacting flows, energy conversion systems, heat and mass transfer, and fluid mechanics.

Authors:

Kaushik Nonavinakere Vinod North Carolina State University
William L. Roberts King Adbullah University of Science and Technology
Tiegang Fang North Carolina State University