Vehicle emission standards have become more and more stringent and have driven the development of advanced engine design with low-cost emission control technologies. For small diesel engine which is used in three-wheel (3W) passenger and load carrying vehicles, it was major task to improve lower engine rpm torque and performance to comply with stringent exhaust emissions standard as well, especially for Oxides of Nitrogen (NOx) and Particulate Matter (PM) emissions. Bharat Stage (BS) VI emission standards for three-wheel vehicles was implemented from April 2020 onwards in India.
Water injection technology has proven advantageous for low-cost solution with Mechanical fuel injection system on small diesel engines, Intake port water injection is the easiest method to introduce water to engine cylinder, which calls for minimal modification of existing engine structure. In the present study 435cc naturally aspirated DI Diesel engine used for three-wheel vehicle was explored by adding water injection system on engine. Water injection is an effective way to reduce NOx emissions. A series of experiments were carried out on engine test dynamometer as well as on vehicle chassis dynamometer on naturally aspirated single cylinder diesel engine with the modification of intake manifold for adding port water injector and required sensors on engine. Water was injected with multi hole injector into intake manifold at 2 bar pressure to create water mist at late suction stroke. Water injection systems consist of input sensors like engine speed sensor, pressure sensor, temperature sensor which are controlled by electronic controller unit (ECU) to provide metered water injection to engine.
Results infer, intake port water injection at late suction stroke is beneficial for NOx emission to meet India BS6 emission norms on Diesel 3-wheeler vehicle. India BS6 emission was met on 3-wheeler vehicle with margin of 36% for CO, 33% for NOx, 24% for HC+NOX and 20% for PM by combination of small percentage of EGR, water injection at 2 bar pressure and Diesel oxidation catalyst.