(279h) Natural Convective Heating in Food Materials in Cylinders

Heating and cooling of food materials in liquid or suspension form is a common industrial operation.In the absence of mixing,natural convection is the mechanism for heating in containers.As most of the food materials follow Non-Newtonian rheology,the prediction of heat transfer rate is complex. In the present experimental work ,condensed milk of various dilutions were used in steel containers of L/d ratio 1 and 2.The volume of liquid varied from 50cc to 500cc.Cooling and heating were affected by immersion in isothermal water bath(accuracy with in 1K).Water temperature was varied from 25 to 85C.Radial and axial temperature distributino in the food liquid was obtained at one axial location and five radial locations , using pt 100 sensors. A discussion on the experimental temperature profiles,heat flux and heat transfer coefficients varying with experimental parameters are discussed.Comparison with theoretical models will be presented