Thermodynamic performance of absorption‐compression hybrid refrigeration cycles based on lithium nitrate+1‐butyl‐3‐methylimidazolium nitrate/water working fluid

Abstract

In this paper, LiNO 3 (lithium nitrate)-[BMIM]NO 3 (1-butyl-3-methylimidazolium nitrate)/H 2 O is presented for absorption-compression hybrid refrigeration. The thermophysical properties and corrosion of this ternary system were measured. The performance of this hybrid system using LiNO 3-[BMIM]NO 3 / H 2 O was studied and compared with those based on LiBr (lithium bromide)/ H 2 O, LiNO 3 /H 2 O, and LiNO 3-[MMIM][DMP] (1,3-dimethylimidazolium dimethylphosphate)/H 2 O. Results showed that the hybrid refrigeration cycles can work at much lower generator and evaporator temperatures in comparison with the pure absorption cycle. Generator temperatures of both hybrid cycles based on this working fluid were lower than those using the other working fluids. At different refrigeration temperatures, the generator temperatures of both hybrid cycles using this presented working fluid were reduced about 7 and 10 K, respectively, in comparison with those based on LiBr/ H 2 O. Compared with other working fluids, both single-and double-effect hybrid systems using this new working fluid achieved a larger coefficient of performance around 0.88 and 1.6, respectively. Additionally, the exergetic efficiency for both hybrid cycles is also about 10% larger than that using LiBr/ H 2 O. And this working fluid shows an excellent thermal stability below 598.32 K and acceptable high-temperature anti-corrosion to metallic materials. Moreover, the hybrid cycle using LiNO 3-[BMIM]NO 3 /H 2 O of 80 kW has a shorter payback period of 5.51 years when utilizing solar energy as the driven heat source. Therefore, LiNO 3-[BMIM]NO 3 /H 2 O shows great advantages in the absorption-compression hybrid cycles.

Techno‐economic assessment of novel and conventional working fluid mixtures for two‐stage double‐ and triple‐effect absorption refrigeration systems

“…7 Except for NH 3 /H 2 O, all other inorganic options include salts which may be difficult to handle in practical applications because ABR operating conditions must be carefully chosen so that their solubility limits are not violated, otherwise undesired crystallization may occur. Ionic liquids are receiving increased attention, with reports indicating that mixtures of imidazolium-based compounds with inorganics such as LiNO 3 in water refrigerant 8 or purely imidazolium-based absorbents with refrigerants such as R1234ze(E) 9 enable increase of COP in ABR systems. These are promising fluids which require further experimental research to ascertain their potential for wider use in view of higher price and viscosity than conventional options.…”