Higher injection pressures (IPs) have increased performance, and split injection
facilitates a simultaneous reduction of soot and oxides of nitrogen
(NOx) emissions when the injection timing is optimized in diesel
engines. The impact of fuel IP and split injection strategies on performance and
emission in compression ignition (CI) engines with biodiesel blends are studied
along with its impact on combustion efficiency. Comparisons of performance,
combustion, and emission characteristics of karanja and jatropha blends with
diesel are carried out with various fuel IPs and split injection to find the
optimal injection conditions. Jatropha and karanja biodiesel are independently
blended with diesel with a blend percentage of 20% (biodiesel 20%, diesel 80%)
as J20 and K20, respectively. Experiments are conducted with J20 and K20
biodiesel blends at various IPs (500, 1000, 1200 bar) and with various split
injections (10, 15, 20, 25, 30, 35%), and the results are compared with diesel.
It is found that J20 produces a 4% reduction in brake specific fuel consumption
(BSFC) and around 7% higher thermal efficiency over diesel except at full load,
and K20 performed similarly to diesel at all loads. Increasing the IP and
splitting the injection improved the engine performance characteristics. Also
increasing the IP helped in reducing the hydrocarbon (HC) emissions and
performing split-injection-facilitated reduction of NOx emissions.
Compared to diesel and J20, K20 with a combination of IP of 1200 bar and split
injection of 15% produced improved performance and reduced emissions.