Clear Juice Heaters Do We Need Them?

Current practice is to install clear juice heaters ahead of first effect evaporators to ensure that the juice entering the evaporator is above its boiling temperature, allowing flashing to occur on entry. The alternative, of allowing the juice heating to take place in the evaporator, is sometimes rejected on the basis that heating transfer performance of an evaporator is very poor when operating in the juice heating regime. To allow this alternative to be evaluated on a quantitative basis, available data on the relative heat transfer performance of juice heaters and Kestner evaporators have been collated, providing estimates of the difference in heating surface area required. By combining this information on heating surface area requirement with equipment costs, it is possible to make a rational assessment on whether it is advisable to dispense with clear juice heaters by installing extra heating surface area in the first effect evaporators.