Thermodynamic Analysis of the ORC with Turbine Bleeding and Regeneration

To perform thermodynamic analysis of the ORC with turbine bleeding and regeneration, steady-state condition and no pressure drop in any equipment are assumed. The analysis of modified ORC can be given as follows (Desai and Bandyopadhyay, 2009)  

Direct contact heater The intermediate liquid at state 2 enters a regenerator where the low-pressure vapor from the turbine (state 7) supplies heat. Heated liquid at the intermediate pressure (state 8) enters a direct contact heater. A direct contact heater is basically a mixing chamber, where the extracted fluid from the turbine (state 6) mixes with the liquid and the hot mixture (state 3) enters into the second pump. The mixture leaves the heater as a saturated liquid at the intermediate pressure. From mass and energy balances of direct contact heater, the fraction of the working fluid extracted from the turbine may be calculated as follows  

Heat addition process The saturated liquid at the intermediate pressure is elevated to the maximum operating pressure of the system by the second pump. The liquid at the maximum operating pressure (state 4) enters the evaporator. The evaporator is a heat exchanger that transfers the heat from a heat source to the working fluid at a constant pressure, and it heats up the working fluid to the required condition (state 5), usually saturated vapor. The amount of heat addition in the evaporator is given as 

Expansion process The high-pressure vapor generated in the evaporator flows through the turbine and produces shaft work. The shaft work obtained from the turbine is expressed by the following equation  

Heat rejection process (Process 9-1) This is a constant pressure heat rejection process in the condenser. The turbine exhaust is condensed in a condenser after it transfers a portion of heat through the regenerator. The condenser heat rejection rate is 

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