General issues on cycles

This session introduces the concept of cycle and the corresponding notations which will be used in the analysis of systems.

The link below gives you access to the relevant textbook.

Course reference:

To follow the presentation, go to the next step

(Session realized on 06/16/11 by Renaud Gicquel)

η = \frac{τ}{Q}

Heat released: Q₀
Losses by convection, conduction and radiation from the boiler or the combustion chamber
Losses from flue gases
Heat supplied to the fluid: Q₁

Net power produced by the machine τ
Thermodynamic efficiency, or internal efficiency η_i, ratio of power produced τ to Q₁
Auxiliary equipment, friction…

without friction
heat exchange between the fluid and the external sources is reversible (with no temperature difference)
intermediate phases: adiabatic and reversible, i.e. isentropic

Engine cycle
$η = \frac{T_{1} - T_{2}}{T_{1}}$
Regeneration cycle

$η = \frac{T_{2}}{T_{1} - T_{2}}$

$η = \frac{T_{1}}{T_{1} - T_{2}}$

difference in temperature between the machine and the hot and cold sources
hot and cold sources non isothermal
mechanical irreversibilities
temperatures reached at the outlet of compression and expansion not equal to those of the hot or cold sources

This session allowed us to define the concept of cycle efficiency and to make some recalls on the theoretical Carnot cycle.