Where do you want to go ?

Accumulation of Energy

Closed
System

ΔEsys

The diagram below shows a

in which mass flows into and out of a system.

Heat and work interactions also occur.

Consider the process for an interval of time from t1 to t2, where t2 > t1.

At t1 the energy in the system is: Esys(t1).

At t2 theenergy in the system is: Esys(t2).

What is the change in energy of the system during the process from t1 to t2?

Enthalpy Form of the 1st Law for Open Systems

Lesson 5E: page 2 of 9

Just as we did in the previous lesson, we will analyze a process that takes place over a time interval from t1 to t2.
In a transient process, the energy of the system may be different at t1 than it is at t2.
Our goal is to derive an equation to help us evaluate how much the energy of the system changes during such a process.
But, keep in mind that at any time, Esys is made up of internal energy, kinetic energy and gravitational potential energy.
The place to start is the enthalpy form of the 1st Law for open systems.
What do you think the next step is ? Integration ?
Flip the page and see for yourself.