Second Law (Exergy) Analysis of Cogeneration System

Abstract

The thermal performance of power generating and consuming devices can be improved significantly, both during design and operation. Turkey's electric energy demand is growing at an average of 6–8% yearly. Cogeneration facilities have an important role in the country's energy strategy, because a substantial amount of Turkey's energy need has been met by cogeneration facilities in recent years. In the present study, the chemical and physical exergy and exergy destruction of the cogeneration system was calculated with the BASIC program by using second law analysis. Performance of the cogeneration system is also discussed, based on the second law (exergy) concept.

Keywords:

• chemical and physical exergy
• cogeneration system
• second law analysis

Notes

^a Data are shown with more significant figures than justifiable in practice to allow for ease of checking computer-generated values.

^b Molecular weight M = 28.967. Molar analysis (%): 78.80 N₂, 21.14 O₂, 0.03 CO₂, 0.03 H₂O (g).

^c Molecular weight M = 28.254. Molar analysis (%): 75.60 N₂, 16.55 O₂, 4.42 CO₂, 3.43 H₂O (g).

^d Molecular weight M = 16.043.

^e Nominal value.

^a Exergy destruction rate within a component as a percentage of the total exergy destruction rate within the cogeneration system (Eq. (28)).

^b Exergy destruction rate within a component as a percentage of the exergy rate entering the cogeneration system with the fuel (Eq. (27)).

^c Includes the exergy loss accompanying heat transfer from the combustion chamber. Value determined using the nominal pressure at state 10 given in Table 1.