Abstract
In the paper presented is a novel concept to utilize the heat from the
turbine bleed to improve the quality of working fluid vapour in the
bottoming organic Rankine cycle (ORC). That is a completely novel solution
in the literature, which contributes to the increase of ORC efficiency and
the overall efficiency of the combined system of the power plant and ORC
plant. Calculations have been accomplished for the case when available is
a flow rate of low enthalpy hot water at a temperature of 90 °C, which is
used for preliminary heating of the working fluid. That hot water is
obtained as a result of conversion of exhaust gases in the power plant to
the energy of hot water. Then the working fluid is further heated by the
bleed steam to reach 120 °C. Such vapour is subsequently directed to the
turbine. In the paper 5 possible working fluids were examined, namely
R134a, MM, MDM, toluene and ethanol. Only under conditions of 120 °C/40 °C
the silicone oil MM showed the best performance, in all other cases the
ethanol proved to be best performing fluid of all. Results are compared
with the "stand alone" ORC module showing its superiority.
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