Aspen Plus simulation of NH3-H2O-NaOH and NH3-H2O-KOH ternary cycles

Abstract

The NH<inf>3</inf>-H<inf>2</inf>O is the most frequently utilized refrigerant-absorbent binary mixture in the vapor absorption refrigeration system (VARS) for low-temperature applications, but this mixture has the disadvantage of rectification requirement. To overcome this disadvantage, the researchers suggested the addition of salt to the binary NH<inf>3</inf>-H<inf>2</inf>O mixture. In this paper, a simulation of the ternary NH<inf>3</inf>-H<inf>2</inf>O-salt mixtures implemented in the VARS is presented. The NaOH and KOH salts are selected in the mass fraction range of 0 to 30% with 50 and 55% NH<inf>3</inf> massconcentrations. The Aspen Plus process tool has been used to perform the simulation study. The addition of NaOH and KOH salts to the binary NH<inf>3</inf>-H<inf>2</inf>O mixture leads to an increase in thecoefficient of performance (COP) of the VARS with a simultaneous reduction in the initial generator operating temperature. The decrease in the generator temperature is slightly higher after adding NaOH salt than that by adding the KOH salt. TheCOP of thecycle increases after adding salt up to 20% salt mass fraction and then starts decreasing. The rise in the evaporator temperature leads to a gradual rise in theCOP of the ternary NH<inf>3</inf>-H<inf>2</inf>O-saltcycles. TheCOP of the ternary NH<inf>3</inf>-H<inf>2</inf>O-NaOHcycle is greater than that of the ternary NH<inf>3</inf>-H<inf>2</inf>O-KOHcycle under the same operating conditions. © 2022