Consider an air-standard Otto cycle. At the beginning of the compression process, the pressure and temperature are 1 bars and 300 K. The displacement volume is 2 liters, compression ratio is 10 and the pressure at the end of the combustion is 4 times the pressure at the end of the compression.Use cold-air standard calculations and determine:1-the pressure, temperature and volume at each state and fill in the below table. 2-the net work per cycle. 3- the thermal efficiency of the cycle.

(2) Describe briefly why the following statements are wrong. (a) "Hot cup of coffee becoming cold spontaneously is an entropy-decreasing process. So the law of entropy increase can be violated." (b) “Air conditioners require bulky external unit, exhausting heat to outside. With the technology constantly advancing, external unit will be eliminated in the future."

A steam turbine drives an air compressor-all power produced by the turbine is sent to the compressor; there is no extra power produced. Steady-state operating data are provided on the figure. Assume the ideal gas model for air, and ignore stray heat transfer and kinetic and potential energy effects. Steam 1 STATE DATA for SYSTEM P, = 30 bar T, = 600°C m = 1.5 kg/s n = 80% P2 = 3 bar P3 = 1 bar T3 = 27°C Turbine Compressor %3D 2 Air

In a Diesel cycle, the air at the beginning of the isentropic compression is at 1 bar and the volume is 0.85 L. The displaced volume of the cycle is 0.78 L, the temperature at the end of the compression process is 690 K, the pressure at the end of the expansion process is 2.32 bar, the specific heat ratio is =1.32, the specific heat at constant volume Cv = 0.75 kJ/kg.K and the gas constant is 287 J/kg.K for air. The compression ratio is: Choose. The specific heat at constant pressure in kJ/kg.K is: Choose. The maximum temperature of the cycle in K is: Choose. The temperature at the end of the expansion process of the cycle in K is: Choose.. the heat rejected in kJ/kg of air is: Choose.