The authors proposed an ammonia-water cycle for power and refrigeration cogeneration which employs a splitting and absorption unit to adjust the desired solution concentrations. Energy efficiency and exergy efficiency of this cycle are found to be 27.3% and 57.6%, respectively, at the cycle highest heat addition conditions of 450°C /111bar. Nevertheless, a large exergy destruction takes place in the heat transfer and throttling process of this cycle. In this paper, three proposals are investigated to recover the energy of the heat transfer and throttling process. The weak ammonia/water solution is superheated by internal heat recovery, and then its energy is converted into useful outputs by: 1) sending the superheated ammonia-weak stream into the turbine, and the energy is directly converted into the power output: 2) and 3) introducing an ejector to the cycle, the superheated stream is used as the primary stream, the turbine exhaust and the evaporator outlet stream are used as the secondary stream, respectively, the energy is indirectly convert into power or refrigeration output. Simulations show that the three proposals enable the increments of 2.9%, 0.8% and 0.7%, respectively, in the exergy efficiency over the base cycle. Obviously, the first proposal has superiority in term of the thermal performance, while the latter two proposals have some advantages in respect of the operation, maintenance and capital costs.
Development of Secondary Stream in Oscillatory Flow through Curved Pipes.