Q2: A 1.78 L four-stroke petrol engine was tested at 2500 rpm. The developed brake power is 28 kW and the brake specific fuel consumption (bsfc) is 290 g/kW.hr. Air consumption is measured by means of air-box method with orifice diameter 3.2-cm and discharge coefficient 0.62 and the pressure difference across the orifice is 150-mm-water. The ambient pressure and the temperature in the test room is 101 kPa and 20 °C. Assume: CV = 43.9 MJ/kg, PH20 =1 =10³ kg/m³, , comb = 98%, nmech 87%. (i) Determine the bmep, AFR, nv, power loss as friction, th,b. (ii) draw up the heat balance sheet on percentage basis, if the cooling water flow is 15 kg/min; rise in temperature of cooling water is 33 °C; exhaust gas temperature is 485 °C; Cpw is 4.2 kJ/kg.K and Cpexh is 1.25 kJ/kg.K.

Elements Of Electromagnetics
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Author:Sadiku, Matthew N. O.
Publisher:Sadiku, Matthew N. O.
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Q2: A 1.78 L four-stroke petrol engine was tested at 2500 rpm. The developed brake power is
28 kW and the brake specific fuel consumption (bsfc) is 290 g/kW.hr. Air consumption is
measured by means of air-box method with orifice diameter 3.2-cm and discharge coefficient
0.62 and the pressure difference across the orifice is 150-mm-water. The ambient pressure and
the temperature in the test room is 101 kPa and 20 °C. Assume: CV = 43.9 MJ/kg,
PH20 =10³ kg/m³, comb = 98%, mech = 87%. (i) Determine the bmep, AFR, №v, power loss as
friction, th,b. (ii) draw up the heat balance sheet on percentage basis, if the cooling water flow
is 15 kg/min; rise in temperature of cooling water is 33 °C; exhaust gas temperature is 485 °C;
Cpw is 4.2 kJ/kg.K and Cpexh is 1.25 kJ/kg.K.
Transcribed Image Text:Q2: A 1.78 L four-stroke petrol engine was tested at 2500 rpm. The developed brake power is 28 kW and the brake specific fuel consumption (bsfc) is 290 g/kW.hr. Air consumption is measured by means of air-box method with orifice diameter 3.2-cm and discharge coefficient 0.62 and the pressure difference across the orifice is 150-mm-water. The ambient pressure and the temperature in the test room is 101 kPa and 20 °C. Assume: CV = 43.9 MJ/kg, PH20 =10³ kg/m³, comb = 98%, mech = 87%. (i) Determine the bmep, AFR, №v, power loss as friction, th,b. (ii) draw up the heat balance sheet on percentage basis, if the cooling water flow is 15 kg/min; rise in temperature of cooling water is 33 °C; exhaust gas temperature is 485 °C; Cpw is 4.2 kJ/kg.K and Cpexh is 1.25 kJ/kg.K.
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