Managing Condensation on Overhead Surfaces Using Microcapillary Film

Introduction: Hot pressurized water is commonly used to clean food processing equipment, causing condensation to form on cool surfaces.  The presence of moisture is associated with an increased risk of microbial proliferation.   We have developed an adhesive-backed film containing open microchannels for use on overhead surfaces.  A capillary force generated by the microchannels increases the surface to volume ratio of condensate droplets, thereby increasing the evaporation rate.

Purpose: The purpose of this study was to evaluate the evaporation rate of condensate on surfaces covered with microcapillary film relative to control surfaces.

Methods: The study was designed to model condensation on pipes, where water droplets accumulate in a “drip line” by migrating to the lowest point. A two inch wide film containing capillary channels was applied lengthwise along the bottom of a 2 inch ID steel pipe cooled to 45°F. Condensation was formed using a commercial steam cleaner until steady state dripping was achieved on both surfaces. After removal of the humidity source the time to droplet disappearance was measured.

Results: The average time to droplet disappearance of condensate on the film was 31 min (+/- 5) compared to 298 min (+/- 152) for the hanging drops on the control surfaces (n = 64).  The variability observed in the evaporation rate on control surfaces was caused by the volume difference in hanging drops.  Larger droplets took significantly longer to evaporate (maximum = 520 min) than smaller droplets (minimum = 45 min).

Significance: The use of microcapillary film has been demonstrated to increase the evaporation rate of condensate.  The use of this film may be beneficial in managing condensation on overhead surfaces in food processing facilities.