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N,N-dimethylethanolammonium (DMEA) based ionic liquids with carboxylate anions are very important in organic synthesis, gas absorption, biological and pharmaceutical applications. The fundamental physiochemical properties will give a platform to better understanding of their nature for scientific community. Here in this work, five DMEA based protic ionic liquids (PILs) with carboxylates were synthesized and their physicochemical properties such as density (ρ) and speed of sound (u) were measured as a function of temperature from (293.15-343.15) K at 0.1 MPa pressure. Several derived thermophysical properties such as molecular volume (Vm), standard entropy (S°), isothermal expansion coefficient (α) and isentropic compressibility (βs) have been calculated using experimental data. The effects of carboxylate anion chain length and temperature on physicochemical properties have been discussed. The crystal potential energy (UPOT) of ionic liquid compared with MX type of inorganic salt and discussed for ion interaction in PILs.

Many zeotropic refrigerant mixtures are being proposed as alternatives to CFCs and HFCFs refrigerants that are being phased out. The main advantage in the use of zeotropic mixtures is the possibility of reduction in entropy generation in the condenser and evaporator by matching the glides of refrigerant and heat transfer fluid. Glide matching is difficult with some zeotropic mixtures due to the nonlinear variation of enthalpy with temperature during phase change. Also, there is a distinct possibility of formation of pinch points with some mixtures, resulting in entropy generation. In this paper, the performance of four mixtures of R32, R134a, R125, R143a and R23 are studied as alternatives to R22 and R502 from thermodynamic as well as temperature pinch points of view. The results demonstrate the importance and the need for pinch point analysis in the evaluation of alternative zeotropic refrigerant mixtures.Many zeotropic refrigerant mixtures are being proposed as alternatives to CFCs and HFCFs refrigerants that are being phased out. The main advantage in the use of zeotropic mixtures is the possibility of reduction in entropy generation in the condenser and evaporator by matching the glides of refrigerant and heat transfer fluid. Glide matching is difficult with some zeotropic mixtures due to the nonlinear variation of enthalpy with temperature during phase change. Also, there is a distinct possibility of formation of pinch points with some mixtures, resulting in entropy generation. In this paper, the performance of four mixtures of R32, R134a, R125, R143a and R23 are studied as alternatives to R22 and R502 from thermodynamic as well as temperature pinch points of view. The results demonstrate the importance and the need for pinch point analysis in the evaluation of alternative zeotropic refrigerant mixtures.