The condensing unit is one of the most important elements of the steam turbine of a combined heat and power
plant. Defects in elements of the condensing unit lead to disturbances in the steam turbine operation, its failures and
breakdowns, as well as efficiency losses of the plant. Therefore, the operating personnel need to know the cause of
the malfunction and to correct it immediately. There are no diagnostic models of condensers in the Republic of Kazakhstan
at the moment. In this regard, a mathematical model of a condenser based on the methodology of Kaluga
Turbine Plant (KTP) has been developed. The mathematical model makes it possible to change the input parameters,
plot dependency diagrams, and calculate the plant efficiency indicators. The mathematical model of the condenser
can be used to research ways for the improvement of the condensing unit efficiency, for diagnostic purposes of the
equipment condition, for the energy audit conduction of the plant, and in the training when performing virtual laboratory
research. Using static data processing by linear regression method we obtain that the KTP methodology of
condenser calculation is fair at cooling water temperature from 20 °C to 24 °C, but at cooling water temperature from
20 °C to 28 °C, the methodology of JSC "All-Russia Thermal Engineering Institute" (JSC "VTI") is used. One of the
ways to increase the condenser efficiency has been proposed. It is the heat transfer augmentation with riffling annular
grooves on tubes. This method increases the heat transfer coefficient by 2%, reduces the water subcooling of the
heating steam by 0.9 °C, and decreases the cooling area by 2%.

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