Vapor pressure measurement of electrolyte solution and its impact on regeneration process in TRAB

Abstract

As a rapidly developing heat-electricity conversion technology in recent years, thermally regenerative ammonia-based battery (TRAB) is characterized with the advantages of high power density and recyclability. Compared with the chemical reaction in TRAB, the thermophysical properties of battery electrolyte is lack of investigation. In this paper, the vapor pressures of a typical TRAB electrolyte, CuSO4-(NH4)2SO4–NH3–H2O, were measured from 333.15 K to 373.15 K. The common-used e-NRTL model was applied to fit the experimental data and describe the vapor-liquid equilibrium property of solution, with maximal relative deviation of 1.98% and average absolute relative deviation (AARD) of 0.66%. Thereafter, the regeneration requirement of TRAB was analyzed. The regeneration temperature is mainly influenced by regeneration pressure and Cu2+ concentration, while NH3 concentration shows insensitive effect on the regeneration temperature. To avoid too low regeneration pressure, the regeneration temperature needs to be higher than 94 °C with regeneration pressure higher than 80 kPa. Through the results obtained in this paper, persuasive reference can be provided for the prediction or simulation on the working process of TRAB. The results in this paper will contribute to the follow-up studies on the regeneration process of TRAB, especially the achievement of recycling of ammonia.

Keywords

• Thermally regenerative ammonia battery
• Vapor pressure
• Static method
• e-NRTL model
• Regeneration