Analysis of ammonia/water and ammonia/salt mixture absorption cycles for refrigeration purposes in fishing ships

In this work, the use of waste heat energy of jacket water in diesel engines of fishing ships was analysed for use as a heat source for absorption refrigeration systems. The thermodynamic simulation of an absorption refrigeration cycle with three different working fluid mixtures that use ammonia as a refrigerant was carried out. This analysis was assessed in terms of the cooling demand and cycle performance as a function of the evaporator, condenser and generator temperatures. Moreover, the need for rectifying the vapour stream leaving the generator was analysed together with the drag of the fraction of non-evaporated liquid to the absorber. The results show that the NH3/(LiNO3 + H2O) and NH3/LiNO3 fluid mixtures have higher values of COP as compared to NH3/H2O fluid mixture, the differences being more pronounced at low generation temperatures. If the activation temperature is set to 85 degrees C, the minimum evaporation temperatures that can be achieved are -18.8 degrees C for the cycle with NH3/LiNO3, -17.5 degrees C for the cycle with NH3/(LiNO3 + H2O) cycle and -13.7 degrees C for the NH3/H2O cycle at a condensing temperature of 25 degrees C. Also, for the NH3/ (LiNO3 + H2O) fluid mixture, it has been demonstrated that the absorption refrigeration cycle can be operated without a distillation column and in this case the water content in the refrigerant stream entering the evaporator is less than 1.5% in weight at the operating conditions selected. (C) 2014 Elsevier Ltd. All rights reserved.