Advanced injection cooling concept for Organic Rankine Cycles

The present experimental and numerical investigation is about an efficiency increasing and/or cost-reducing measure for Organic Rankine Cycle (ORC) systems. In such systems, a high proportion of the self-consumption of the system lies in the condensation of the working fluid due to the operation of ventilators or cooling pumps. Typically, the condenser heat exchanger is one component, where the processes of desuperheating, condensation and in some applications also subcooling takes place. Especially, the process of desuperheating requires huge heat exchanger surfaces due to the low heat transfer coefficients of the gas phase. The proposed measure aims in reducing the share of desuperheating in the condenser by injection cooling in front of the condenser. Thus, on the one hand, the condenser surface area can be smaller, reducing investment costs. On the other hand, if the surface area is kept constant, the expansion backpressure can be reduced due to the improved heat transfer in the condenser, leading to a higher power output of the expansion machine. The present study demonstrates the benefit of this optimization measure by an experimental investigation, which is complemented by a numerical analysis. With this measure and R1233zd-E as working fluid, the condensation pressure can be decreased by up to 11.2% leading to an increase in net power output of 7.9%. With this, quite substantial additional revenue is generated especially with a high full load operation.     «

The present experimental and numerical investigation is about an efficiency increasing and/or cost-reducing measure for Organic Rankine Cycle (ORC) systems. In such systems, a high proportion of the self-consumption of the system lies in the condensation of the working fluid due to the operation of ventilators or cooling pumps. Typically, the condenser heat exchanger is one component, where the processes of desuperheating, condensation and in some applications also subcooling takes place. Especi...     »