An analysis of the feasibility and characteristics of photoelectric technique applied in defrost-control

An innovative photoelectric technology is presented in this paper for detecting frost in the field of defrost-control of refrigerator or freezer applications. Experiments were conducted with a small-scale laboratory test section under natural convection conditions. Two agreeable properties of the new technology, “on–off” and “linear”, have been demonstrated by the experiments. The first property provides an effective judgment of the defrost-control strategy while the second one is suitable for developing an accurate measurement of the frost height. The characteristics (electric current, environment temperature, metal surface temperature, light intensity and sensor location) that affect the properties were investigated for the development of this technology.