Estudio comparativo del rendimiento energético de un sistema de aire acondicionado trabajando con R134A y R1234YF para automoción

Abstract

This research deals with the comparative study of the performance of the automotive air conditioning system among R134a y R1234yf, through the bibliographic review of similar studies. Subsequently, a thermodynamic model was implemented; to simulate the real performance of the system and compare its energy performance working with both refrigerants. The heat exchangers were modeled with the e-NTU method, considering the phases of the refrigerant within them, the condenser is divided into three zones and the evaporator in two. The compressor was modeled using efficiency curves as a function of the pressure relationships. To validate the model, experimental data from a system were used real automotive A/C. Simulations were carried out considering input variables, which allow the study of the system in a global and real way under local operating conditions. The results show that the rotational speed of the compressor, the airflow to the condenser, and cabin and ambient temperatures influence system performance. lt concludes that the present work reproduces the automotive A/C system in a global way considering the air temperatures around the exchangers. Keeping a flow constant intermediate air towards the evaporator, with R1234yf a temperature of 13K discharge less than that obtained with R134a at idle (airflow to the condenser 0.3778 m3 / s, compressor speed of 950rpm and airflow to the evaporator of 0.0472 m3 / s). There is also a COP for R1234yf of 3.30% lower than R134a, this difference is increases up to 5.24% under road conditions (airflow to condenser 0.59 m3 / s, a compressor speed of 3000rpm andan airflow to the evaporator of 0.118 m3 / s).