Abstracto
- Mixtures of the orange-peel diterpene limonene with the fossil hydrocarbons pentane or isopentane were studied as potential working fluids for organic Rankine cycles. Evaporation rates of the mixtures at 22 °C and 87 kPa vary linearly with mass fraction of the alkanes in the liquid phase. The enthalpies of vaporisation of the mixtures also vary linearly with composition. When considered under the operation conditions of a binary geothermal plant in Costa Rica (pentane, 26% Carnot efficiency), mixtures with 20% content of limonene as ORC fluids show calculated overall Carnot efficiencies of 22% (pentane) and 24% (isopentane), a result to be used as benchmark for further thermal-efficiency study. The estimated flash points of the 20% limonene mixtures are 30 °C higher than for the pure hydrocarbons.