Re: [Phys-L] irreversible quasistatic

[John Denker <jsd@av8n.com>]

On 07/30/2016 10:05 AM, Daniel V. Schroeder wrote:
> You compare the system temperature to the reservoir temperature.  If
> they're infinitesimally close, you can call the process reversible.
> If not, the process is irreversible.

That's not true in general, and I'm pretty sure it's not relevant
to the question that was asked.

> Your cycle B requires either a hotter hot reservoir or a colder cold
> reservoir than cycle A. 

That's not clear at all.  It is entirely possible to have
an irreversible engine with only the usual two reservoirs.
For example, imagine a system with two subsystems, namely
a reversible engine driving a brake, where the brake is
heat-sunk to one of the two usual reservoirs.

Irreversibility is about entropy, not about temperature per se.