Spatial Variation of Convective Heat Transfer Coefficient in Air Impingement Applications

Spatial variation of heat transfer is an important factor in air impingement systems. Temperature data were obtained when a jet at room temperature impinged on a flat object initially at −50 °C to estimate heat transfer under freeze‐thaw conditions. Single and double circular jets and slot jets were examined. Temperature data were fit into empirical relationships for predicting heat transfer coefficients and their spatial variation for conditions common in impingement freeze‐thaw applications. For processing conditions involving cooling, the impingement surface was initially heated to a temperature of 70 °C and allowed to cool when subjected to impingement with room temperature air.