Registro de acceso restringido Este recurso no está disponible en acceso abierto por política de la editorial. No obstante, se puede acceder al texto completo desde la Universitat Jaume I o si el usuario cuenta con suscripción. Registre d'accés restringit Aquest recurs no està disponible en accés obert per política de l'editorial. No obstant això, es pot accedir al text complet des de la Universitat Jaume I o si l'usuari compta amb subscripció. Restricted access item This item isn't open access because of publisher's policy. The full--text version is only available from Jaume I University or if the user has a running suscription to the publisher's contents.

This paper presents an energy performance evaluation of two low-GWP refrigerants, R1234yf and R1234ze(E), as drop-in replacements for R134a. Tests are carried out in a monitored vapour compression system combining different values of evaporation and condensation temperature, and without/with the adoption of an internal heat exchanger. The parameters analysed are volumetric efficiency, cooling capacity and COP and they are presented taking R134a as baseline. Results show that without IHX the average volumetric efficiency for R1234yf and R1234ze is 4% and 5% lower compared with R134a. The cooling capacity obtained with R1234yf and R1234ze is reduced, with an average difference of 9% and 30% without IHX, respectively. Also, COP values are about 7% lower for R1234ye and 6% lower for R1234ze than those obtained using R134a. Finally, the use of an internal heat exchanger reduces the COP differences for both replacements.Keywords: Drop-in, energy performance, R1234yf, R1234ze(E), R134a, vapour compression system. Nomenclature

No abstract

No abstract

Climate change is demonstrated through global surface temperatures increase in the last century. To stop this phenomenon, new regulations that ban or taxes greenhouse gas fluids (HFC among them) have being approved. In the medium term, only low-GWP refrigerants will be permitted in developed countries. HFO are synthetic fluids that show similar properties to used HFC. Among them, one of the most promising is R1234ze(E). This refrigerant presents good environmental properties and can be used in most of HVACR applications, pure or mixed with HFC or natural refrigerants (mainly CO2). This paper collects the most relevant research about R1234ze(E) thermophysical and compatibility properties, heat transfer and pressure drop characteristics, and vapour compression system performance; separating those works that considers R1234ze(E) pure or blended. Once analyzed literature available, it can be concluded that pure R1234ze(E) is a good option only in new HVACR systems. Nevertheless, if it is combined with other refrigerants also reduces considerably the final GWP value, maintaining efficiency parameters at levels that allow them to replace R134a, R404A or R410A in existing systems with minor modifications.