COMPARATIVE ENERGETIC AND EXERGETIC ANALYSIS OF INDIVIDUAL OR COGENERATIVE SYSTEMS WITH STEAM TURBINES FOR PRODUCING HEAT AND MECHANICAL WORK.

The energy consumes for district or industrial heating and electrical energy are in most of cases concomitant. The paper analyses from the point of view of the First and Second Laws of Thermodynamics the advantages of producing heat and mechanical power each one individually or through cogeneration. It is clearly pointed out that the energy balance induces the idea that the most efficient conversion process is to produce heat in an individual boiler while the mechanical power production in a steam turbine system is much less efficient. The energetic analysis accounts only for the interactions with the external medium considering any heat loss as depending only on its magnitude and neglecting its temperature level as quality factor. The large energy loss in the condenser of the steam turbine system decreases dramatically the energetic efficiency of the overall system even if this heat transferred to the environment is useless due to its low temperature level. The exergetic analysis that accounts for both the quantity and quality of a heat carrier shows the real level of efficiency for each process advocating for the production of both heat and mechanical power by cogeneration. [ABSTRACT FROM AUTHOR]