A general mathematical model for forced air precooling of spherical food pr
oducts in bulk is developed. The food products are arranged inline to form
a rectangular parallelepiped. Chilled air is blown along the height of the
package. The governing equations for the transient two-dimensional conducti
on with internal heat generation in the product, simultaneous heat and mass
transfer at the product-air interface and one-dimensional transient energy
and species conservation equations for the moist air are solved numericall
y using finite difference methods. Results are presented in the form of tim
e-temperature histories. Experiments are conducted with model foods in a la
boratory scale air precooling tunnel. The agreement between the theoretical
and experimental results is found to be good. In general, a single product
analysis fails to predict the precooling characteristics of bulk loads of
food products. In the range of values investigated, the respiration heat is
found to have a negligible effect.