Mitigating Electrochemical Effects in Resistive Frost-Detection Sensors

Demand defrosting is a well-established strategy for improving defrost efficiency in refrigeration systems, and resistive frost-detection sensors provide a cost-effective means of enabling such control. However, copper electrode resistive sensors operating in water-based environments are susceptible to electrolysis, which degrades electrode integrity and compromises measurement reliability. This study investigates the impact of electrolysis on sensor performance and evaluates the effectiveness of an intermittent powering method in mitigating these effects. Two sensor excitation methods were experimentally tested: continuous voltage application and pulsed DC excitation with a 1.7% duty cycle. The results demonstrated that continuous excitation caused erratic measurements and electrode degradation due to ongoing electrochemical reactions. In contrast, the pulsed DC excitation method stopped observable electrolysis effects, leading to stable measurements and improved sensor longevity. These findings highlight pulsed DC excitation as a practical and effective solution for enhancing the accuracy and durability of resistive frost-detection sensors, making them more suitable for long-term use in commercial refrigeration system evaporators.