EXPERIMENTAL ANALYSIS OF A COMMERCIAL REFRIGERATION SYSTEM OPERATED WITH R22 AND THE HYDROCARBON R1270

Abstract

This work contributed to the knowledge on the study to replace halogenated fluids by natural refrigerants reducing the damage to the environment. Primarily, it was important to know the operation limits of the experimental facility, with maximum refrigerating capacity of 17.5 kW. At the same time to the first objective, instrumentation and control strategies were adopted, allowing extending the focus of this research such as the energy savings. The experimental facility has been submitted at three different configurations: the first one depicted a conventional refrigeration system that, basically, consists of a reciprocating compressor working at nominal frequency, two concentric tubes heat exchanger, a thermostatic expansion valve (TEV) and R22 as work fluid; in the second case, the compressor speed was controlled by an inverter frequency drive and an electronic expansion valve replaced the TEV; and finally it was proposed a third system configuration, exactly to the second one, in which was used R1270 (propylene) as the working fluid. The experimental results showed that the system operating at frequencies below 60 Hz and the implementation of a PID controller in the expansion device enabled the improvement in the COP of the automated system compared to the COP of the conventional system, which used an on-off controller. Consequently, the automation of the conventional system reduced by 35% the average monthly energy consumption. The replacement of R22 by R1270 increased even more the values of the COP and reduced the environmental damage, calculated by the total equivalent warming impact (TEWI). It was showed that the automation and the replacement of a traditional fluid by a hydrocarbon decrease up to 39% the damage to the environment for this specific application. Keywords: refrigeration, air conditioning, control, R22 and R1270.