Recent content by PatrickAndrews

Thanks for that. Clarity achieved. Cheers

Perspective is the key point Ok, I think I get this now. For a closed (dm/dt=0, but not isolated) system, I've drawn the attached diagram. From the system's perspective, the external temperature(s) from which heat is transferrred into the system is unknown. This means that the dS-system...

Wow...thanks for that insight -especially since it was so quick. "From either blocks perspective, the heat transfer is a reversible process" I did not realize that reversibility was relative, believing that the definition of irreversibility for a process was that dS universe >0 It seems to me...

"deltaQ at the boundary...which is the reversible part..." That is exactly my problem, because my belief has been that heat transfer at the boundary is **irreversible if Texternal<>Tboundary** ie heat transfer via a finite temperature difference occurs. ie there is an irreversibility at the...

I just reread your answer more closely and noticed the 'internal heat transfer' reference. Just to be clear...am I correct in thinking that an (irreversible) process of heat transfer due to temperature difference at the boundary has no effect on Sgen (Sgen is sometimes referred to as including...

My question relates to entropy generation in a closed system ΔS=dQrev/T for a reversible process ΔS=dQ/T + Sgen for an irreversible process This seems to suggest that Sgen arises because of the irreversibility of the heat transfer process (eg across a finite temperature difference). If...

Thank you. This is very helpful.

Many thanks

"system" My understanding is that a reservoir maintains constant temperature when transferring heat, but a system of finte capacity does not. "all heat transfer processes are irreversible" This has me a bit confused. Surely the (idealised), quasistatic process by which eg a reservoir at T+dt...

Thanks very much for the rapid responses. I really appreciate this support. My confusion has been partly dealt with, in that I can now calculate the energy which becomes unavailable as work in an irreversible process (as a function of entropy increase). A further issue continues to nag at me...

I'd like some help to understand how to calculate "lost work" for irreversible heat transfer across a finite temperature difference. I'd also be grateful for any links to the derivation of a clear, general expression for lost work (in terms of entropy). Thanks