Influence of condenser conditions on organic rankine cycle load characteristics

Tobias Gabriel Erhart, Ursula Eicker, David Infield

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

A 7 MWth combined heat and power plant (CHP) based on an organic Rankine cycle (ORC) with 5.3 MWth and 1 MWel nominal output is analyzed. A district heating system serves as heat sink; the entire system is heat-led. Two examples for winter and summer operation are shown. The observed characteristics of the condenser are compared to results of a theoretical model. Variable mass flows, temperature levels (72 °C–95 °C) and temperature spreads result in varying condensation temperatures and pressure levels in the condenser (90 mbar to 150 mbar). High mass flows on the secondary side and related low temperature spreads improve the heat transfer and increase the condensation rate in the condenser. The monitoring data support the findings of a steady-state condenser model. As a consequence, advantageous load profiles according to the pressure characteristic of the system can be reached. Live steam pressure, pressure difference across the turbine, and flow rate increase. The effect on the electric efficiency is one percentage point in summer and 1.5 percentage points in winter, which translates to a difference in the electric yield of the cycle of about 10%. Furthermore, the data show that the transient sink conditions cause unsteady operation for the entire cycle.
Original languageEnglish
Number of pages9
JournalJournal of Engineering for Gas Turbines and Power
Volume135
Issue number4
DOIs
Publication statusPublished - 18 Apr 2013

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Rankine cycle
Condensation
Cogeneration plants
Temperature
District heating
Heat sinks
Turbines
Steam
Lead
Flow rate
Heat transfer
Monitoring

Keywords

  • condenser conditions
  • organic
  • rankine cycle load characteristics

Cite this

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abstract = "A 7 MWth combined heat and power plant (CHP) based on an organic Rankine cycle (ORC) with 5.3 MWth and 1 MWel nominal output is analyzed. A district heating system serves as heat sink; the entire system is heat-led. Two examples for winter and summer operation are shown. The observed characteristics of the condenser are compared to results of a theoretical model. Variable mass flows, temperature levels (72 °C–95 °C) and temperature spreads result in varying condensation temperatures and pressure levels in the condenser (90 mbar to 150 mbar). High mass flows on the secondary side and related low temperature spreads improve the heat transfer and increase the condensation rate in the condenser. The monitoring data support the findings of a steady-state condenser model. As a consequence, advantageous load profiles according to the pressure characteristic of the system can be reached. Live steam pressure, pressure difference across the turbine, and flow rate increase. The effect on the electric efficiency is one percentage point in summer and 1.5 percentage points in winter, which translates to a difference in the electric yield of the cycle of about 10{\%}. Furthermore, the data show that the transient sink conditions cause unsteady operation for the entire cycle.",
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Influence of condenser conditions on organic rankine cycle load characteristics. / Erhart, Tobias Gabriel; Eicker, Ursula; Infield, David.

In: Journal of Engineering for Gas Turbines and Power, Vol. 135, No. 4, 18.04.2013.

Research output: Contribution to journalArticle

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