A Capillary model approach to simulating water removal from a porous medium during immersion oil frying

A laboratory technique to assist in determining water evaporation from a thin crisp has been described. The method involved the use of disposable 20mul Dade Accupette Pipettes filled with distilled water and immersed in vegetable oil heated to 105 degreesC. A Sony Handycam TRV35 was used to record the evaporating water from the capillary tubes for the duration of the experiment. It could be seen that oil uptake did not take place until the vapour pressure in the capillary tube had decreased below a threshold value. It was also observed that 70 volume percent of water in the heated section of the capillary was removed in about 12s. The rate of evaporation of the remainder of the water was 310 and 245s respectively for a vertical capillary and one offset from vertical by 30 degrees. This was measured by measuring the length of time the water-water vapor interface in the capillary tube took to approach the surface level of the heating oil. The results are to be used to assist in determining the transfer mechanism for water vapour in a thin crisp. In conjunction with some fundamental calculations, it is suggested that the water removal during immersion frying is most likely dominated by a viscous flow regime instead of a diffusion process.