Study on measurement of frost dimensions/distribution and frost crystals scraping force using scanning probe microscope (investigation on influence of humidity)

• Frost dimensions/distribution/scraping force until the primary stage were measured.
• The correlations among frost dimensions/distribution/scraping force were clarified.
• Influences of humidity on frosting process until the primary stage were clarified.
• Main factors governing frosting mass and scraping force were clarified, respectively.

Frosting to a cooling solid surface is often unavoidable and is severe problems. Thus, in order to control the frosting, it is necessary to clarify the mechanism of frosting, both scientifically and technologically. Furthermore, when investigating this mechanism, knowing how frost crystals start to form and grow is very important, therefore, frosting from generation to primary growth stage must be clarified. Since frost crystals dimensions are very small in their generation and primary growth stage, it is essential to conduct these investigations at the micro scale level. In this study, using a scanning probe microscope (SPM), frost crystals dimensions/distribution and scraping force of frost crystals, were measured under fixed surface temperatures, comparing influence of humidity with that of surface temperature via a method proposed by one of the authors. Then, correlations among the above frost crystals dimensions/distribution and scraping force were clarified, comparing with influence of cooling solid surface temperature.