Within the triangle of these notations, there are frequently used applications aimed at cycle simulation and cycle closed loop control. There are many issues regarding accuracy of results and regarding the scope of applications to real gases and to even mixtures of gases and liquids, such as so-called wet compression in open, semi-closed and closed gas turbines. Other accuracy issues apply in wet steam expansion too. The three points often form a link between 3D or 2D analysis and 1D simulation of cycle performance. Such considerations apply to the issue of guarantees or to cycle control methods.

Additionally exergy loss balances are an excellent hint for identifying opportunities and risks of thermodynamic cycles. Polytropic efficiency is a benchmarking key number for identifying exergy losses in turbomachinery blading used for compression or expansion, because it is based on the assumption of a constant dissipation rate during compression or expansion.

Thermodynamic cycles are limited by the achievable maximum design temperature, based on cooling technology and/or material capability. In the case of gas turbines, energy balance methods are frequently used in closed loop control of the operating conditions.

Open issues in the above respect are as examples: Kinetic effects of dissociation to the heat balances used for determination of the hot gas temperature in gas turbines are not really known. The effect of condensation delay to polytropic efficiency in wet steam expansion is still unknown. The effect of local dissipation to the condensation delay and to the droplet size in wet steam expansion is still unknown or unpublished.

Interesting applications are as further examples: “2D or 3D maps of dissipation density or of exergy loss in turbomachinery blading”; “Design of Water-Steam cycles using polytropic efficiencies”; “Exergy loss mechanisms in wet compression applications”; “Relation of self-excitation of blades and dissipation in wet steam expansion”. The space is open for any other related topics.