Thermodynamics Review Problems for Mechanical Engineering Students | Series 25

For this review problem, the very first thing to do is to **draw the P-V diagram** of the said three-process cycle. After creating the P-V diagram of the said cycle, by inspection we can say that the heat that is being added to the cycle is done during the isometric process which is literally process 1 -> 2 and is the only one providing a positive sign heat which means heat that is being added. As we proceed to the computation, the first thing to obtain is the pressure at the start of isothermal process which is P3, and it can only be obtain using the pressure and volume relations during an isothermal process. By using the provided ratio for volumes V1 and V3, we’ve found out that the P3 is equal to 600 kPa. Additionally, since process 2 -> 3 is an isobaric one or constant pressure, P2 is also equal to 600 kPa. Next thing to obtain is the temperature at the end of isometric process, for which we can obtain it using the pressure and temperature ratio during a constant volume process. By using the relation, we’ve found out that 1800°K. And since we now have both T1 and T2, we can now finally solve for the heat that is being added to the cycle and we’ve found out that it is equal to 5389.5 kJ.