So I have to write out nodal equations for a system that I was given, and I started off by drawing out the flow diagram to see where everything was. I'm having trouble starting the nodal equations though. The attachment has 2 diagrams: figure 1 is the correct diagram that models the thermal system, and figure 2 is what I drew out to try and write the nodal equations. I started off at Q1 Q1= (P5-P4)+(P4-P1)+(P1-P5)=0 is this on the right track for a nodal equation? If anyone can explain how to write them or tell me if I'm at least on the right track that would help me so much. Thanks!