| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1732011 | Energy | 2015 | 13 Pages |
•We model an entropy generation of the steam turbine control valves and throttle valves of the heaters.•The control valves and throttle valves regulate the mass flow across the turbine or in to the heaters.•Results of a double throttling mass flow are double-generated entropy and a double loss of work.•The model presents the results of a double throttling entropy generation minimization.
This paper presents entropy generation minimisation model of combined heat and power system. The turbine control valves and heater throttle valves were analysed. The high-pressure control valves regulate the mass flow rate of steam into the turbine, whereas the intermediate-pressure and low-pressure control valves the steam pressure of the turbine extracts 3 and 5. The steam of the turbine extracts 3 and 5 is used for the city-wide heating system purposes by means of the peak and basic heaters. The quantity of the extracted steam used for the city-wide heating system is additionally controlled by the throttles regulating the extracted steam into the basic or peak heater. This results in a double throttling of the extracted steam of the turbine, double generated entropy and a double loss of work. If adequate pressure of the extracted steam of the turbines is maintained by means of the turbine control valves the two heaters for the heating system could operate with the throttles open. As a result, the generated entropy of the throttles of the steam admitted to the heater could be avoided and the amount of generated entropy of the turbine control valves reduced.
