Considerations on heat exchange in a liquid-nitrogen freezer

The paper presents a method of finding out the average convection coefficient along a cryogenical freezing tunnel: and also the determination of the density of the thermal flux changed between the product and chilling environment. There was used a programme (ALGOR-U.S.A) based on the finite element method: the thermophisical properties of the product (lambda,c,rho) were introduced in the computer as average values on a temperature interval (every minute). The convection coefficients varied until the values of the temperatures resulted from the calculation were closed to the experimentally measured temperatures; The obtained data can be used for the design of the cryogenical liquid nitrogen freezers.