Evaluation Of Working Fluid for Solar Operated Organic Rankine Cycle Power Plant

Abstract

This paper evaluates different fluids to be used as working substance in Organic Rankine Cycle (ORC) for power generation. Different organic fluids that have been considered are Rll, R12, Rl13, R123, R134a, R24Sfa, R601, R600a, C6H6 (Benzene), C7Ha (Toluene) and CaRlo (p-xylene). The evaluation has been done on the basis of the thermal efficiency, the physical and chemical properties, cost of the fluids etc. The physical properties like thermal stability, viscosity, thermal conductivity, boiling point and critical pressure and chemical properties like corrosion affinity, reaction with metal, flammability have to be considered for selection of the fluid. Thermal stability of the fluids is affected while working above 390.S.C, which in the present case will not be an issue as maximum cycle temperature is assumed to be 140.C, which is well below the temperature at which the thermal stability of the fluids is questioned. Thermodynamic properties like critical pressure, critical temperature are also significant for selecting the best fluid for aRC. For comparison, certain operating parameters of ORC have to be fixed. Temperature at inlet to turbine and condenser temperature have been assumed to be 140°C and 40°C respectively. Power output, thermal efficiency, operating pressure range, safety and environment friendly are the criteria for the section for the fluid. Specific work output and ideal cycle efficiency for various substances suitable to use for solar operated Rankine cycle have been calculated. For comparison with simple Rankine cycle, calculations have also been done for water.