By using the latent heat of steam exhaust,waste heat of flue gas and environment cold energy,a indirect air cooled system with ammonia Rankine cycle(IAC-ARC) for large coal-fired power plant was presented of considering the performance of steam cooling.With the principle of maximizing the total power,a calculation model of optimal exhaust pressure of steam turbine of off-design operation features was established to optimize the optimal exhaust pressure under different ambient temperature.According to the re...