The drying of thin films of solution applied uniformly to large flexible webs of material is one of the critical unit operations in the manufacture of photographic products, and protective coatings in the packaging industry. This is accomplished in a number of ways but almost all techniques require the forced movement of a gas, usually air, across the surface of the solution.
A thin layer of solution is transported on a flexible web into a tunnel in which heated air, in combination with other sources of energy, impinges on the surface of the solution. The ability of the equipment to evaporate the solvent is critical to the quality and economics of producing the product which is a defectless coated web.
The most important parameter in drying is the heat transfer coefficient profile in the tunnel. In this increasingly competitive manufacturing environment, measurement of the heat transfer coefficient is essential in the optimiztion of process conditions for drying of product, design modifications of exisitng ovens, translation of pilot to plant drying processes and computer simulations of manufacturing drying processes. Knowledge of the heat transfer coefficient becomes extremely valuable in the characterization of production equipment that has been modified several times. The modications may have been for evolving product needs, environmental considerations, and/or equipment up dates (i.e. fan replacement).
So the project scope is to devise an instrument that is capable of measuring average heat transfer coefficients in existing drying tunnels. Note that the actual film being dried is extremely expensive and it is most important to determine drying conditions, time and temperature etc., on a pilot scale and not on the full scale.
It is expected that the instrument or technique will measure the average heat transfer coefficient that is experienced by the moving web inside an actual drying tunnel. Experiments can be conducted at the pilot facility at 600 Main Stret in Cambridge, very close to M.I.T., and, to a lesser extent in the production facility in altham, Mass.