Patent ID: 9574816
Date: 2017-02-21
CPC Classifications: F24F,F25B,F25D

Claim:
1. A refrigerating and air-conditioning apparatus comprising: a refrigeration cycle being formed by connecting a compressor, a condenser, an expansion valve, and an evaporator, the refrigeration cycle performing a cooling operation; an evaporator heating device heating the evaporator; a drain pan receiving drain-water from the evaporator and draining the drain-water; a drain-pan heating device heating the drain pan; a frost detecting device including a light-emitting element that emits light to the evaporator and a light-receiving element that receives reflected light from the evaporator and outputs a voltage according to the reflected light; a control device controlling on-off operation of the evaporator heating device and the drain-pan heating device, the control device, being configured to turn on the evaporator heating device based on the output of the frost detecting device, and then, calculate an inclination of an output voltage of the frost detecting device successively, determine that the frost formed on the evaporator has started to melt when the inclination is 1.5 times or more of an absolute value of an inclination of initial operation, and turn on the drain-pan heating device.