Executive Summary : | A biofuel based generator for low emissions and high performance will be developed through simulation, experiments and field demonstration by Indian Institute of Technology Madras and Mahindra and Mahindra (M&M). Biogas will be the main fuel while biodiesel or diesel will be the auxiliary fuel for ignition. It has been established that the premixed charge compression ignition (PCCI) mode in an internal combustion engine has the potential to operate with alternative fuels with high efficiency. However, PCCI has some specific challenges like wall wetting of the injected fuel, small load range and control of the combustion process. Hence, a novel twin/dual injector pilot-main electronically controlled injection system for avoiding wall wetting problems generally encountered in early injection PCCI operation will be developed and employed. Additionally, a strategy for seamless switching between dual fuel, PCCI and single fuel modes based on the operating condition will be achieved through electronic controls in order to attain a wide load range, low overall emissions including particulates and high efficiency. Initially, the best spray angles, injection quantities of the injectors and injection timings will be determined through CFD simulations for the PCCI and dual fuel and single fuel modes. A combustion chamber geometry that suits the dual-fuel, PCCI and CI modes along with the best compression ratio will be determined through CFD simulation. With the help of M & M, a cylinder head design and combustion chamber will be developed and manufactured for incorporating the twin injectors. A gas injection system will also be developed and installed. In a specially created experimental facility that includes gaseous and particulate measurements as per standards, evaluation of the different combustion modes and their ranges of operation along with the best injection parameters will be done on standard test cycles at IIT Madras. Selection of the fuel injection parameters, pulsed injection strategies and combustion mode based on operating conditions will be done based on detailed experiments. A control system for automatically changing the mode of operation between PCCI/CI and dual fuel in order to cover the entire load range will be developed using in-house developed software. Suitable after-treatment systems will also be explored and installed on the engine. The final configuration will be validated in the laboratory and under field operating conditions with the support of M & M. Both diesel and biodiesel will be used along with biogas in the final experiments. Finally, a report on the fuel injection strategies, mode switching strategies and methods for application in engines of different capacities will be submitted along with the results that compare and demonstrate the potential of the developed system as regards efficiency enhancement and emission reduction. |