Impact Study Of Two Additives?NaOH&LiNO₃? On The Performance Of Ammonia/water Absorption Heat Pump

The main objective of the present thesis is to develop detailed model for absorption heat pump using ammonia as refrigerant.The physical and mathematical model is established using a commercial software to simulate ammonia absorption heat pump system.On this basis,the ammonia absorption heat pump performance is simulated by using the established absorption heat pump model after the addition of NaOH and LiNO₃ salts and the operating characteristics of ammonia absorption heat pump with ternary working fluid were obtained under different working conditions.First,an appropriate thermodynamic property method for the ammonia/water,ammonia/water/sodium hydroxide and ammonia/water/lithium nitrate mixtures is selected according to the available data in the literature.It is found in the literature that Peng-Robinson is the best available method for ammonia/water binary working pair while ELECNRTL method is suitable for ammonia-water-salt ternary fluid using flow-sheeting software ASPEN Plus.To model absorption heat pump cycle,different Aspen-plus blocks for each component and their cross-ponding input data is selected.Both models,for ammonia/water binary working fluid and for ammonia-water-salt ternary mixture are validated by mass balance verification,energy balance verification and EES model data from literature to estimate the accuracy of the models.It is found that models are within mass and energy balance.To verify these models with EES data,nine different parameters are chosen.It is found that,for ammonia/water binary pair all the discrepancies are under 6%and for ammonia-water-salt ternary mixture all the discrepancies are under 7%which shows that both models are valid.The cycle using Ammonia/water as working fluid is modeled first,by keeping circulation ratio constant.Then the ternary mixtures NH₃/H₂O/NaOH and NH₃/H₂O/LiNO₃ are used as the working fluid with a mass fraction 0-12%for both salts separately.The cycle configuration and other parameters remains the same.NaOH and LiNO₃ are only present in the solution circuit.Results shows that addition of salts decreases temperature significantly while simultaneously increasing the COP and decreases the thermal energy required for rectification.For a concentration of 12%LiNO₃,the temperature at the generator decreases by about 14 ⁰C and the COP increases by 18%with respect to the conventional NH₃/H₂O cycle.For a concentration of 12%NaOH,the temperature at the generator decreases by about35⁰C and the COP increases by 29%with respect to the conventional NH₃/H₂O cycle.At the same time thermal energy required for rectification reduced.By using NH₃/H₂O/NaOH with12%salt mass concentration,66%rectification reduction acquired.While by using NH₃/H₂O/LiNO₃ with 12%salt mass concentration,42%rectification reduction achieved.Above all,the addition of NaOH and LiNO₃ to conventional NH₃/H₂O working fluid increases the overall performance of absorption heat pump cycle.