PROBLEMS 2.1 An Engine Working On Otto Cycle Has A Pressure And Temperature At The Beginning Of Compression As I Bar And 20°C Respectively. After Compression, The Temperature Becomes 380°C. The Maximum Temperature Of The Cycle Is Limited To 1500°C. Calculate The Com- Pression Ratio, The Temperature And Pressure At All Cardinal Points, The Air-Standard

 

 

 

PROBLEMS 2.1 An engine working on Otto cycle has a pressure and temperature at the beginning of compression as 1 bar and 20C respectively. After compression, the temperature becomes 380C. The maximum temperature of the cycle is limited to 1500C. Calculate the com- pression ratio, the temperature and pressure at all cardinal points, the air-standard efficiency, the work done per kg, and the mean effective pressure. 2.2 An engine working on Otto cycle has cylinder bore of 210 mm and stroke length of 240 mm. The clearance volume is 1550 cc. The pressure and temperature at the beginning of compression are 1 bar and 17C respectively. The maximum pressure of the cycle is 50 bar. Determine the pressure and temperature at the salient points, the air-standard efficiency, the work done, and the mean effective pressure. What will be the ideal power developed by the engine, if the working cycle per minute is 600? 2.3 A Diesel cycle operates at a pressure of 1 bar at the beginning of compression and the air is compressed to 1/18th of the initial volume. Heat is supplied until the volume is twice that of the clearance volume. Calculate the air-standard efficiency and the mean effective pressure of the cycle. 2.4 A four-cylinder engine operating on a Diesel cycle has cylinder bore of 200 mm and stroke length of 250 mm. The engine speed is 3000 rpm. The pressure and temperature of the air at the beginning of compression are 1 bar and 27C respectively. The clearance volume is 1/15th of the swept volume. The maximum temperature attained by the cycle is 1800C. Determine the pressure and temperature at the salient points, the compression ratio, the air-standard efficiency, the work done per kg of air, the mean effective pressure, and the power developed by the engine. 2.5 For an engine working on a Diesel cycle, the pressures in the cylinder at 20 per cent and 75 per cent of the compression stroke are 1.5 bar and 4 bar respectively. Assuming that the compression follows the law pV = constant, find the compression ratio. The cut-off takes place at 5% of the stroke. What will be the cut-off ratio? If the relative efficiency of the engine compared with the air-standard efficiency is 60%, evaluate the fuel consump- tion in kg/kWh, if the calorific value of the fuel is 40,000 kJ/kg. 2.6 An oil engine operating on a Dual cycle has cylinder bore of 250 mm and stroke length of 300 mm. The compression and expansion ratios are 10 and 6 respectively. The initial pressure and temperature of the air are 1 bar and 27C respectively. Determine the pressure and temperature at all salient points, the air-standard efficiency of the cycle, the mean effective pressure, and the power of the engine, if the working cycles per second are 12. Assume that the heat added at constant pressure is twice the heat added at constant volume. 2.7 An oil engine operating on a Dual cycle has a compression ratio of 15 and compression begins at 1 bar, 30C. The maximum pressure reached is 65 bar. The heat transferred to air at constant pressure is equal to that at constant volume. The expansion and compression follow the law pV125 = constant. Determine the pressure and temperature at cardinal points, the cycle efficiency, and the mean effective pressure of the cycle.