ABSTRACT
Consider the open system sketched in Figure 2.1. The system exchanges heat with the environment, at a rate Q. The environment absolute temperature T0 is equal to the temperature of the boundary penetrated by heat transfer. This means that the control surface defining our system was conventionally drawn through regions of space not affected by the heat transfer interaction Q. In real applications any heat transfer interaction is driven by a finite temperature difference; in Figure 2.1 this temperature difference is located inside the control surface.
