THERMODYNAMIC ANALYSIS OF USE OF FLUOROCARBON WORKING FLUIDS IN POWER GENERATING UNITS OF SMALL SCALE POWER PLANTS

Estimation is given of thermodynamic efficiency of flow diagrams for small scale power plants with a working substance of fluoroorganic composition. A review of existing organic Rankine cycle (ORC) 4 technologies with working media other than those of the fluorocarbon composition has been given. As an object of comparison and replacement by a nonaqueous power plant, a small scale biomass fuelled power plant has been chosen using solid bark waste biomass as a fuel. This plant design is based on the traditional water-steam Rankine cycle. The calculated analysis of thermodynamic efficiency of multicircuit flow diagrams, with staged heat utilization circuits, as well as consecutive heat transfer from one circuit to another, proposed as an alternative to the traditional cycle, has been provided. The efficiency of steam-turbine cycles of the proposed arrangement has been analyzed for octafluoropropane (C₃F₈) and decafluorobutane (C₄F₁₀). The calculation of cycles and processes for new power generating units involved using experimentally substantiated state equations obtained by the authors earlier. The influence on internal cycle efficiency of new small scale power generating units depending on initial live steam pressure at turbine inlet and condensing temperature has been studied. A significant increase of thermal efficiency is noticed for the staged heat utilization arrangement, compared to the water-steam cycle. A number of technological and design advantages have been noted that can be achieved through applying working fluids of the fluorocarbon composition as the working media for small scale thermal power plants.

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