An experimental study of the correlation for predicting the frost height in applying the photoelectric technology

It is found that the photoelectric technology is suitable for the accurate measurement of the frost height. The objectives of this paper are to experimentally investigate the correspondence between the output signal of the photoelectric sensor and the frost height, and then develop a generalized correlation to predict the frost height directly and accurately. The experiments are conducted in a wide range of operating conditions for air temperature 17.7 °C–27.2 °C, relative humidity 21.6% RH to 64.9% RH, air velocity 0.5 m/s to 4.5 m/s and cold surface temperature −10.5 °C to −6.5 °C. Based on 21 groups of experiments with total 600 data, a linear correlation with a relative deviation of ±10% is setup. Further validation of this correlation is conducted by comparing the predicted results with 4 additional experiments, and approximately 95% of the predicted frost heights are consistent with the measured data within a relative deviation of ±10%. These results indicate that the photoelectric technology can predict the frost height directly. The application of the proposed correlation to provide defrost control strategy is also discussed in this paper.