Air is compressed steadily by a compressor from 100 kPa and 27oC to 800 kPa and 290oC. The mass flow rate of the air is 15 kg/min. During the process, the heat is lost from the compressor at a rate of 15 kW to the surrounding at 27oC. Assume air to be an ideal gas and the changes in kinetic and potential energies can be neglected. a) Determine the power required by the compressor, kW. b) Find the minimum power required by the compressor, kW. c) Calculate the isentropic efficiency of the compressor, %. d) Determine the rate of entropy generation during this process, kW/K. e) To prevent the heat loss from the compressor to the surrounding, the compressor is well insulated. Assuming the exit temperature of the air remain the same, find the new power required by the compressor, kW. f) Does the process as in (e) satisfy or violate the second

Calculate the work (in kJ) when substance initially at 218 kPa, 9 m³ is expanded to 61 kPa in a process where PV = Const.

A piston-cylinder device initially contains CO2 at 200 kPa and 400°C and the total enclosed volume is 300 litres. Due to heat loss, the piston moves downwards to a position where it sits on a pair of stoppers and its final enclosed volume is 150 litres. Further heat loss leads to the pressure being reduced to 160kPa. Workout 1) the final temperature, 2) the total work done by CO2 and 3) the total heat transferred to CO2. Also make some comments on the result of heat and create a schematic p-v diagram of the process. The following assumptions are to be made: CO2 is a perfect gas and its molecular mass is 44kg/kmol. The ratio of specific heat capacities, γ (gamma) is 1.3 The volume occupied by the stoppers is to be ignored. There is no leakage in the system There is no friction between the cylinder and piston walls and the piston moved slowly at the same speed therefore, no acceleration. For the conversion from Celsius to Kelvin, use 273 Use 8314.5 J/kmol.K for the universal gas…

2. A steady stream of steam passes through a turbine. The steam inlet conditions are 10MPa, 450°C and 80m/s and at the outlet they are 10kPa, 92% quality and 50m/s. The mass flow of the steam is 12 kg/s. Determine a) the change in kinetic energy, b) the power developed by the turbine, and c) the area of ​​the turbine inlet.