An Experimental investigation was carried out to determine performance, emissions and combustion characteristics of diesel engine using nanoaluminum oxide (n-Al2O3) blended diesel fuel. The n-Al2O3 of size 40 nm was blended into diesel fuel. The different dosing levels studied were 250mg, 500mg, 750mg, and 1000mg. Each dosing levels of nanoparticles were mixed with one litre of diesel to prepare test fuels. The n-Al2O3was dispersed by means of an ultrasonic vibrator in order to produce uniform dispersion of n-Al2O3 in the diesel fuel. nanoAl2O3possess better combustion characteristics and enhanced surface-area-to-volume ratio and hence allows more amount of diesel to react with the oxidizer which in turn enhances the burning efficiency of the test fuels. The diesel fuel with and without n-Al2O3 additive were tested in a direct injection diesel engine at different load conditions and the results revealed that a considerable enhancement in the brake thermal efficiency and substantial reduction in content of NOX and unburnt hydrocarbon (UBHC) at all the loads compared to neat diesel were observed due to nanoAl2O3’s better combustion characteristics and improved degree of mixing with air.
Aqueous cerium oxide at the rate of 50cc per liter was dispersed into diesel and diesel-biodiesel using mechanical agitator and an ultrasonicator for preparing the test fuels. Cerium oxide nanomaterials present in the aqueous cerium oxide exhibit higher catalytic activity because of their large contact surface area per unit volume and can react with water at high temperature to generate hydrogen and improve fuel combustion. Also, cerium oxide nanomaterials act as oxygen buffers causing simultaneous oxidation of hydrocarbons (HCs) as well as the reduction of oxides of nitrogen. The neat diesel and test fuels were tested in an engine without changing the engine system at 0%, 25%, 50%, 75% and 100% load condition and resulted in a considerable enhancement in the brake thermal efficiency, improved brake-specific fuel consumption and decreased concentration of HC, NO x and smoke in the exhaust emitted from the diesel engine due to incorporation of aqueous cerium oxide in the test fuels.
The aging behaviour of ammonium perchlorate hydroxyl terminated polybutadiene composite solid propellant was characterised using uni-axial tensile and stress relaxation mechanical property measurements at regular intervals during an accelerated aging period. The measured properties in the tension test were Young's modulus, breaking load and percentage of elongation at the time of break. In stress relaxation test, the load at the end of 180 min of relaxation was recorded and it was selected as one of the indicators for the study of aging behaviour. Scanning electron microscopy examinations were also conducted for the fractured tensile test specimens during the aging period to observe the microscopic structure of the fractured surface of the propellant after tension test. Relaxation tests with 5% constant strain with 3 h hold duration were simulated using a finite element computer program. The reaction forces were collected for the period of hold duration and compared with the experimental results. The simulated results are in good agreement with experimental results.
List of symbolsAP ammonium perchlorate de/dt, dD/dt strain rate E 0 Young's modulus G shear modulus G a final shear modulus G i initial shear modulus HTPB hydroxyl terminated poly butadiene K bulk modulus K a final bulk modulus K i initial bulk modulus k[t] rate of change of property RH relative humidity P(t) property at any time under accelerated aging P o initial property t time t o initial time UTM universal testing machine a i , t i Prony coefficients e strain s stress t relaxation time constant n Poisson's ratio
This study attempts to identify the optimum dosing level of aqueous aluminum oxide nanofluid in diesel to improve combustion and engine performance and also to overcome the engine emission issues especially, the oxide of nitrogen, smoke, and the particulate matter. The aqueous aluminum oxide (aluminum oxide nanoparticle aqueous 5 wt % suspension) is used as a nanofluid. The dosing level of nanofluid is varied from 30 cc to 60 cc in steps of 10 cc for the performance study. Fuel blend properties such as calorific value, density, kinematic viscosity, and flash point are determined using ASTM standard test methods. Among all blends, the D+50AN showed a maximum improvement of about 5.9% in brake thermal efficiency (BTE) and remarkable reduction in NOx, smoke, HC, and CO as 15.6%, 22.34%, 31.82%, and 13.79%, respectively, at maximum rated power output.
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