An ideal otto cycle has a compression ratio of 8. at the beginning of the compression process, air is at 95 kpa and 27 c, and 750 kj/kg of heat is transferred to the air during the constant-volume heat-addition process. taking into account the variation of specific heats with temperature, determine

(a) the pressure and temperature at the end of the heataddition process

(b) the net work output

(c) the thermal efficiency

(d) the mean effective pressure for the cycle.

approximate answers:

(a) 4000 kpa 1500 k

(b) 400 kj/kg

(c) 50 percent

(d) 500 kpa.

Amass of m 1.5 kg of steam is contained in a closed rigid container. initially the pressure and temperature of the steam are: p 1.5 mpa and t 240°c (superheated state), respectively. then the temperature drops to t2= 100°c as the result of heat transfer to the surroundings. determine: a) quality of the steam at the end of the process, b) heat transfer with the surroundings. for: p1.5 mpa and t 240°c: enthalpy of superheated vapour is 2900 kj/kg, specific volume of superheated vapour is 0. 1483 m/kg, while for t 100°c: enthalpy of saturated liquid water is 419kj/kg, specific volume of saturated liquid water is 0.001043m/kg, enthalpy of saturated vapour is 2676 kj/kg, specific volume of saturated vapour is 1.672 m/kg and pressure is 0.1 mpa.

Line joining liquid phase with liquid and solid phase mixture is known as: a) liquidus b) solidus c) tie line d) none of the mentioned

Water at the rate of 1 kg/s is forced through a tube with a 2.5 cm inner diameter. the inlet water temperature is 15°c, and the outlet water temperature is 50°c. the tube wall temperature is 14°c higher than the local water temperature all along the length of the tube. what is the length of the tube?