Avaliação teórico - experimental de técnicas de controle fuzzy aplicadas a sistemas de refrigeração

Abstract

This research deals with the experimental study of a vapor compression refrigeration system, with variable speed compressor using fuzzy control. The experimental facility is composed by a semi-hermetic compressor, concentric tube evaporator and condenser, thermostatic expansion valve with manual equalization and electronic expansion valve (VEE). The experimental facility was completely instrumented using PT-100 temperature sensors, piezoresistive pressure transducers, coriolis mass flow meter, using analogical signal amplification, conditioning and logic programming controller (PLC). The LABVIEW software was used for monitoring and operating of the experimental facility. An adaptive fuzzy control was applied for the compressor speed and a PI (proportional and Integral) fuzzy control for the electronic expansion valve (VEE), working with models obtained from the experimental techniques and also from data of the compressor manufacturer. In the analysis of the results was validated the strategy control, showing an better performance of the refrigeration system related with the quality, sensibility and strict regulation of the superheating degree, between 2°C and 7°C for frequencies between the 30 Hz and 4 0 Hz. Under these conditions, the energy savings were of the order of up to 20%, since the system worked in regions of high values of COP, associated with regions of high heat transfer coefficients.