An ORC is a suitable means of carrying out this purpose. The ORC works with a high molecular mass organic working fluid with the characteristic of having a phase change of liquid to vapor occurring at a temperature which is lower than the phase change of water to steam for a given pressure. The recovery of low-grade heat can be achieved using organic fluids. These low-grade heat sources can be from biomass energy, solar energy, geothermal energy, and industrial waste. This work presents an analysis of the organic Rankine cycle (ORC) using R143a, R600a, R134a, and RC318 as working fluids under constant external conditions. An EES program has been developed to parametrically compare the first and second law efficiencies and turbine size factor with an increase in turbine entry temperature, heat source temperature, turbine efficiency and pinch point temperature difference.