Acoustic determination of thermophysical properties and critical parameters for R410A and critical line of x CO2+(1− x) R410A

• Autor(a) principal: Ribeiro, Nuno
• Data de Publicação: 2006
• Outros Autores: Costa, Tânia, Aguiar-Ricardo, Ana, Esperança, José M. S. S., Pires, Pedro F., Guedes, Henrique J. R.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.13/3910
• topic: R410A; Critical Line of xCO2 + (1 - x)R410A; Acoustic determination; Thermophysical properties; .; Faculdade de Ciências Exatas e da Engenharia

The thermophysical properties and critical parameters for the alternative refrigerant R410A (a near azeotropic refrigerant mixture containing difluoromethane (R32) and pentafluoroethane (R125) (50 wt % of each)) were investigated using two different acoustic techniques. The critical behavior of the system xCO2 + (1 - x)R410A was also investigated. Experimental data of speed of sound in liquid R410A from (253 to 338) K and pressures up to 65 MPa were measured using a pulse-echo method. Derived thermodynamic properties were calculated, combining our experimental data with density and isobaric heat capacity values published by other authors. Measurements of the critical temperature Tc and pressure pc on (R410A) and mixtures of xCO2 + (1 - x)R410A were performed using another simple ultrasonic time-delay technique. The binary critical line was determined over the whole composition range, showing that this system deviates only slightly from ideality since the critical line is a continuous line. The Peng-Robinson equation of state with conventional mixing and combining rules was used to correlate the binary experimental data.