Investigation of different steam Rankie cycles from thermodynamic point of view

In the thesis, unlike the studies in the literature, Rankine cycles with 4 stage expansion, 2 open feed water heaters, 1 closed feed water heater, with and without reheating are modeled and analyzed according to the first and secon laws of thermodynamics. A computer program for the Rankine cycles was developed using EES (Engineering Equation Solver) software. The amount of heat supplied to the boiler, the total power produced by the turbines, the total power consumed by the pumps, the total power produced by the cycle, the amount of heat rejected by the condenser to the environment, first and second law efficiencies of the cycles, second law efficiencies of open feedwater heaters and closed feedwater heaters were investigated according to turbine 1 inlet temperatures between 500℃ and 620℃ and turbine 1 pressures between 18000 kPa and 30000 kPa. As the turbine 1 inlet temperature is increased, the maximum power obtained in the reheat cycle was found to be 1.22 times higher than the maximum power obtained in the unheated cycle. The maximum first law efficiencies (thermal efficiencies) were determined to be 42.21% and 41.11% in the cycles with and without reheating, respectively. Considering the maximum second law efficiencies, 91,46% in the reheated cycle and 71.28% in the unheated cycle were obtained. In both cases, it has been determined that there is a negligible change in the total power consumed by the pumps and the second law efficiency of the open feedwater heater 2 (OFH2). As the turbine 1 inlet pressure is increased, the power produced in the reheated cycle and the unheated cycle are 52459 kW and 43523 kW, respectively. The proportional value of the powers produced in both cycles is 1.2. The efficiencies calculated according to the first law of thermodynamics are very close to each other, around 40% for the cases with and without reheating. It has been determined that the second law efficiency of the cycle is 90% on average in the case with reheat and 70.5% on average in the case without reheating. The total power consumed by the pumps was in the same range with and without reheat and increased by 76% under increasing pressure conditions. The increase in the second law efficiency of OFH2 in the unheated condition was 75%, and in the reheated condition it was 5.83%.