The Helmhoz function is a combination property defined by th

The Helmhoz function is a combination property defined by the sum of internal energy plus the negative value of temperature times entropy. Consider a closed system that undergoes a cycle which starts with the initial pressure equal to 600 [kPa] and the initial Helmholz function equal to 300[ kJ/kg]. During the cycle 200[kJ] of heat was transferred to the system.,

a) What is the value of the Helmholz function after the cycle is complete?

b) How much work was performed on the surroundings during the cycle?

Solution

As helmholtz function is a system property, it will remain the same after the completion of cycle.

a) F=U-TS = 300 kJ/kg

b) q=u + w, u =0 (for a cycle), w=q=200kJ