Roll-Bond Evaporator Defrost Sensor Positioning for Uniform Defrosting

The patent divides the defrosting process into two sequential modes: a first defrost mode that operates for a predetermined time period, and a second defrost mode that operates after a cooling period. This temporal segmentation of the defrosting process allows the thin roll-bond evaporator to be defrosted uniformly by controlling the duration and intensity of heating cycles, preventing any single region from overheating while ensuring complete defrosting of the entire evaporator surface.

The patent implements periodic defrosting cycles that alternate between heating phases (first and second defrost modes) and cooling phases (cooling mode with compressor operation). This periodic action allows the evaporator to be heated uniformly across its entire surface area, then cooled to reset the temperature distribution, repeating this cycle until complete defrosting is achieved. The periodic nature ensures that the thin evaporator structure receives distributed thermal energy rather than concentrated heating that would cause non-uniform defrosting.

The patent positions the defrost sensor at a specific location on the evaporator: the end farther from the blowing fan. This local positioning strategy is based on the understanding that this specific location experiences different thermal characteristics compared to other parts of the evaporator. By monitoring the temperature at this critical location, the system can accurately determine defrost completion for the entire evaporator without requiring multiple sensors distributed across the surface, thus achieving high measurement precision with minimal sensor complexity.

The defrost sensor leverages the existing temperature variations naturally occurring on the evaporator surface during the defrosting process. By strategically placing the sensor at the location that last reaches defrost temperature (the end farthest from the heating source), the system uses the evaporator's own thermal behavior to provide defrost completion information. This self-service approach eliminates the need for additional heating elements, multiple sensors, or complex control mechanisms to determine when defrosting is complete.