System-surroundings energy exchange

Processes or phenomena assumed to occur in a closed system without energy exchange with the surroundings. 

A thermodynamic system (closed system) is one that interacts with the surroundings by exchanging heat and work thru its boundary an isolated system is one that does not interact with the surroundings. The state of a system is determined by the values of its various properties, eg, pressure, volume, internal energy, etc. A system can be composed of a finite number of homogeneous parts, called phases, or there can be a single phase. For some applications, it may... 

In the previous three sections we have seen that three different thermodynamic driving forces are associated with three different systems (the NVE, NVT, and NPT systems). The driving forces for the three systems are summarized in Table 1.1. In the simplest case (the NVE system), in which the system does not exchange energy or material with its surroundings, the isolated system moves naturally to... 

Unlike djS, dgS may be of any sign. The positive value dgS/dt relates to an increase in the system entropy due to the matter and/or energy exchange with the surroundings. The negative value of dgS/dt relates to the case when the positive entropy outflow from the system to the sur roundings (for example, due to heat or matter outflow) is greater than the positive entropy inflow. 

An energy balance (Chapters 7 through 9). If the amount of energy exchanged between the system and its surroundings is specified or if it is one of the unknown process variables, an energy balance provides a relationship between inlet and outlet material flows and temperatures. 

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