Four kilograms of an ideal gas are contained within a piston-cylinder device. the gas undergoes a polytropic process with a polytropic exponent of 1.5. the initial pressure is 3 bars, the initial volume is 0.1 m3, and the final volume is 0.2 m3. if the change in specific internal energy of the gas during the process is -4.6 kj/kg, determine the net heat transfer, in kj.

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.

Agas is compressed from vi 0.3 m, p 1 bar to of v2 0.1 m3, p2--3 bar. pressure and volume are related linearly during the process. for the gas, find the work, in kj.

Heat transfer by is the fastest mode of heat transfer that requires no intervening medium. a)-conduction b)-convection c)-radiation d)-conduction and convection