## HEAT RATE TRANSFORMATION COEFFICIENT, EXTRACTION STEAM EFFICIENCY AND MAIN CYCLE EFFICIENCY

**GUO Min-chen, WEI Nan, YANG Yong-ping (North China Electric Power University, Beijing 102206,China)**

In the analysis of thermodynamic system of a coal fired power plant, both the heat rate transformation coefficient ξ i and the extraction steam efficiency η i are the parameters revealing the grades of bled steams ,and they can be related through the concept of main cycle .The concept and thermodynamic efficiency of main cycle are expounded in this paper. And based on main cycle ,the parameters of the heater q i?γ i?τ i which reflect state of the thermodynamic system are provided. Heat rate transformation coefficient and extraction steam efficiency are dependent on the construction and parameters of every node of the main cycle , and the relational expression can be obtained by solving the simultaneous linear coupled equation respectively. With strict mathematical derivation ,the relational expression η M=η i/ξ i which indicates the relationship between heat rate transformation coefficient and the extraction steam efficiency are deduced . This expression not only points out that the main cycle efficiency relies on the parameters of every node, but also can be used to calculate the main cycle efficiency. Based on a 300MW unit, the matrix equations are interpreted and its design parameters are calculated.

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