The criteria for evaluation of efficiency of heat technical installations considering general energy costs with the aim of increasing their environmental friendliness and reducing negative effect on the environment

摘要

The features of the physical meaning of the thermal coefficient useful action (CUA) ηt as a criterion for the efficiency of reversible direct circular processes are considered. In particular, we demonstrate that accounting for all energy costs when applying ηt is made by adopting a number of assumptions by default. In order to expand the possibilities for conducting thermodynamic assessments of the efficiency of various thermal power plants, a new criterion of efficiency Ku is proposed as a coefficient that takes into account in a comparable form all types of energy spent on the implementation of the cycle. In determining the criterion Ku, useful effect obtained from the implementation of a direct circular process is considered to be the specific work of the expansion of the working fluid in the cycle. Such work, in particular, can be the work of steam expansion in the turbine. The total energy cost is the sum of the specific heat supplied to the working body in a circular process and the specific mechanical work spent in the cycle on compression and pressure increase of the working body. In particular, the work is taken into account in a comparable form-taking into account the heat that was spent on its production. The analysis of the Ku criterion is carried out. As a result of the analysis we have established that at transition from the general physical model of reception of specific work of expansion in direct circular process for which Ku criterion can be applied, to the special case assuming a number of assumptions, Ku criterion can become equal to thermal coefficient useful action of a cycle. Using the Ku criterion, the efficiency of Carnot and Rankine cycles on a saturated pair is compared. The Ku score showed that the Rankine cycle was more efficient.