Do North Face Jackets Shrink

First law of thermodynamics (1)

The third course has helped to establish the equation that governs the principle of conservation of energy in the general case of open systems. The proof is based on a systemic approach. In
stock exchanges energy must be taken into account, compared to a closed system, energy trade following:

• the energy carried by the incoming and outgoing masses,
• work flow related to mass transfer.

To simplify the writing of the equation, it adopted a change of variable h = u + Pv. We introduce the enthalpy.
Also note the presence in the equation of two entries in the internal energy:

• a total U shape (expressed in kJ) for the energy in the system at time t,
• une forme massique u (exprimée en kJ/kg), pour les masses traversant la frontière du système.