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ENCIT 2022
19th Brazilian Congress of Thermal Sciences and Engineering
TEMPERATURE CONTROL OF DOMESTIC REFRIGERATORS BASED UPON THE ELECTRIC CURRENT OF THE COMPRESSOR
Submission Author:
Gustavo Ardigó de Souza , SC
Co-Authors:
Gustavo Ardigó de Souza, Raul Liston, Everton Machado, Alexsandro Santos Silveira, Christian Hermes
Presenter: Gustavo Ardigó de Souza
doi://10.26678/ABCM.ENCIT2022.CIT22-0256
Abstract
Over the years, household refrigerators have undergone several control systems upgrades. The main change was the migration of electromechanics bulb thermostats to thermistor-type temperature sensors, connected to an electronic board. However, such an update implies a high cost of manufacturing and maintenance. This study was aimed at developing an alternative low-cost control strategy capable of regulating the internal temperature of a domestic refrigerator using only the electric current of the compressor as the process variable, which is sensitive to the variation of thermal load in refrigeration systems. To this end, an electronic board capable of measuring the compressor current with good accuracy and controlling the refrigerator was developed. Such a technique and electronic board were applied to a single-door refrigerator using a single-speed compressor. The device was tested at two different ambient temperature levels (16 and 25°C) based on the IEC62552 norm. Also, three different types of tests were performed: pulldown, defrost recovery and ambient temperature transitions. All experiments were performed in a climate chamber that controls temperature, humidity and air speed according to the current standards. The control algorithm consisted of a dynamic reference modification for a PI controller, together with a set of empirical conjectures. The electric current control technique was able to maintain the refrigerator temperature within acceptable tolerance levels, around ±1°C, figures quite like those obtained from the baseline temperature control, albeit costing twice as lower.
Keywords
Current Control, Single Speed Compressor, Household Refrigerator
