uring engine torque。 Cooling water flow rate was kept constant at 300 L/h (8。33 × 10−5m3/s)。 Table 3 shows the

detailed specification of the test set-up。 Horiba analyzer (http://www。horiba。com/in/) is used for determination of the unburnt hydro-carbons (HC) in the exhaust。 In addi- tion, KM9106 Quintox flue gas analyzer (http://www。 kane。co。uk/online-catalogue/emissions-monitoring/ km9106) is used for NOx, CO2 and CO emissions in the

exhaust。 Sensors of the exhaust gas analyzers are installed

in the exhaust pipe at the outlet。

To prove the accuracy of the experiment an uncertainty analysis is necessary, as uncertainties and errors may occur due to instrument selection, calibration, working condition, observation and method of conducting the test (Panwar et al。 2010)。 Percentage uncertainty (±4。33 %) of

the engine test data (cylinder pressure-crank angle varia- tion @ 1500 r。p。m) obtained after conditioning and pro- cessing 10 cycles is calculated using roots sum square method (Doebelin and Manik 2007)。 Table 4 shows the gas specifications of the exhaust gas analyzers mention- ing the accuracy of the measured parameters。

Results and discussion

Engine performance and exhaust emissions test results for blends of 10, 20 and 40 % crude rice bran biodiesel (CB10, CB20, CB40) along with diesel are examined at compression ratio (C。R) 15, 16, 17 and 18。

Fig。 1 Trans-esterification process for crude rice bran biodiesel production

Table 1 Physical and chemical properties of crude rice bran oil

Table 3 Specification of test set-up

  Make type Kirloskar

Properties

C14:0 Myristic acid (saturated), % 0。34

C16:0 Palmitic acid (saturated), % 19。5

C18:0 Stearic acid (saturated), % 2。3

C18: 1 Oleic acid (monosaturated), % 43

C18: 2 Linolic acid (polysaturated), % 32

C18: 3 Linolenic acid (polysaturated), % 1。6

C20 Arachidic acid (saturated), % 0。7

C22 Higher fatty acids, % 0。6

FFA content, % 16

Density at 15 °C, kg/m3 920

Iodine value 96

Saponification value 187

Moisture, % 0。8

Oryzanol, % 2。0

Table 2 Crude rice bran biodiesel properties

Propertyparameters Crude rice bran biodiesel

Density at 15 °C (kg/m3) 877

Viscosity at 40 °C (mm2/s) 3。57

Carbon Residue (% w/w) 0。244

Engine type Single cylinder 4-stroke DI, water cooled Compression ratio Ranging from 12 to 18

Rated power 3。75 kW@1500 R。P。M

Stroke 110 mm

Bore 87。5 mm

Connecting rod length 234 mm Injection nozzle 3 hole Fuel injection pressure 195 bar Injection timing