Abstract
The equations for intermittent heat transfer during icing conditions are presented and solved by means of an electrical analog. The results of the analog investigation are compared favorably with measured time-temperature data previously reported in the literature. The analysis shows that contrary to the experience with steadily heated ice-prevention systems, the energy requirements for ice prevention using intermittent heating decrease with increasing ice-accretion rate. Corroborative evidence is found in the literature. The thermal analyzer is used to demonstrate how the protection afforded for propeller deicing may be increased without an increase in the energy required from the electrical supply of the airplane and without major redesign of existing propeller heaters. In the case of jet-engine guide-vane deicing, for a typical installation, the indicated power requirements are 1 kw per engine. In each case the minimum energy requirements occur when large amounts of power are applied for very short intervals of time. Suggestions for further reductions in power are given.
