B51ET THERMODYNAMICS ASSIGNMENT to be submitted by Friday Week 6 (i.e. 24th October before 12.15PM) A four-stroke spark ignition petrol engine has 6 cylinders and a total swept volume of 3.5 litre. The clearance volume of the complete engine is 0.35 litres. Identify (name) and analyse the appropriate ideal cycle. air properties: Cv: 0.718 kJ/kgK; Cp: 1.005 kJ/KgK ambient temperature: 17 °C maximum pressure in cycle: 70 bar The cycle starts at point one with the highest process volume and lowest pressure of 1bar. 1.) Draw a realistic cycle in a pressure (p) and volume (V) graph in the left, and the appropriate ideal cycle in the right graph. In the ideal cycle number the key process points. 2.) Calculate the pressure, temperature and volume for all 4 process points. 1 2 3 4 p [bar] T [K] V [dm³ or litre] 3.) Calculate the compression ratio of this ideal process. p V p V B51ET THERMODYNAMICS ASSIGNMENT to be submitted by Friday Week 6 (i.e. 24th October before 12.15PM) 4.) Calculate the specific (mass) heat addition, heat rejection and the work input and output of the engine. 1?2 2?3 3?4 4?1 S w [kJ/Kg]] q [kJ/kg] 5.) Calculate the mass specific cycle process work. 6. ) Calculate the mass of air in a single cylinder and in the complete engine. 7.) Calculate the power output of the ideal engine at 5000 rpm. 8.) Calculate the efficiency of the engine. 9.) Calculate the fuel consumption in litres for one hour at a workload of 3000 rpm. Octane (48MJ/Kg with a density of 0.88 kg/l) 10) A test shows that the fuel consumption of the engine is actually 1.9 times that calculated in section (9) above when tested at half maximum power at 3000rpm. Suggest why this may be the case.
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