Thermodynamic analysis on a modified Kalina cycle with parallel cogeneration of power and refrigeration

A modified Kalina cycle with parallel cogeneration of power and refrigeration abbreviated as PPR-KC was proposed and investigated. The cycle cogenerates refrigeration by further reclaiming heat resource from the boiler. A parallel branch of work solution is split at the outlet of the mid-p-absorber, and it undergoes pumping, generation, rectification and condensation before evaporation for refrigeration. Then the vapor from the evaporator goes to a mixer at the low-p-absorber inlet via a subcooler, while the dilute solution from the generator heats the basic solution in the second recuperator before going to the mixer via a throttle valve. The split fraction which determines the relative percentage of work solution flow rate for power generation or refrigeration can be altered arbitrary at user's demand. The parameter optimization was conducted and the optimum work concentration is 0.5 and the optimum basic concentration shall be adjusted with different split fraction. Under temperatures of heat resource/cooling water are 400 °C/30 °C and minimum pinch temperature differences in heat exchangers with/without flue gas are 20/5 K respectively, the comprehensive power recovery efficiency of the PPR-KC reaches 27.2%, which is 9.85% and 20.24% respectively higher than those of the cogeneration cycle proposed by Liu et al. and the Kalina cycle.