**Author details**

Heinz Herwig and Christoph Redecker

\*Address all correspondence to: h.herwig@tuhh.de

Institute for Thermo-Fluid Dynamics, Hamburg University of Technology, Germany

#### **References**


[6] Rant, Z. (1956). Exergie, ein neues Wort fuer technische Arbeitsfaehigkeit. *Forschung im Ingenieurwesen* 1956;22 36-39.

**7. Conclusions**

160 Heat Transfer Studies and Applications

Despite its apparently low popularity, entropy generation is a crucial aspect of every heat transfer process. Every real technical process includes the generation of entropy, which at some point has to be discharged to the ambient. It has been shown that every energy flow has an entropic potential, which is the amount of entropy that can be discharged to the ambient along with the energy flow. It therefore sets the limit for all wanted processes associated with this energy flow. Based on this, the *energy devalution number* has been introduced, which quantifies the part of the entropic potential which is lost in a transfer process. The *energy devalution number* is applicable to all processes in which energy is transferred and is recommended for

In the examples it has also been shown how different heat transfer situations can be compared with each other. Such comparisons can be made on very different levels, reaching from system assessment (i.e. to compare different systems) to more detailed studies regarding the optimi‐ zation of subsystems which are part of an overall heat transfer system. It has also been shown how existing simulation results can be reused at different temperature levels, effectively

Institute for Thermo-Fluid Dynamics, Hamburg University of Technology, Germany

[1] Moran, H. & Shapiro, H.. *Fundamentals of engineer thermodynamics*, 5th edn. New York:

[2] Baehr, H. & Kabelac, S. *Thermodynamik*, 14th edn. Berlin, Heidelberg, New York:

[3] Herwig, H. & Kautz, C. *Technische Thermodynamik*. München: Pearson Studium; 2007.

[4] Incropera, F., DeWitt, D., Bergmann, T. Lavine, A. *Fundamentals of heat and mass trans‐*

[5] Nellis, G. & Klein, S. *Heat transfer*. Cambridge: Cambridge University Press; 2009.

their assessment especially with regard to sustainability.

lowering the cost of CFD simulations.

Heinz Herwig and Christoph Redecker

John Wiley & Sons; 2003

Springer Verlag; 2009.

*fer*, 6th edn. New York: John Wiley & Sons; 2006.

\*Address all correspondence to: h.herwig@tuhh.de

**Author details**

**References**


**Analytical and Experimental Investigation**
