Heat Transfer Performance of Vertical Tube Falling Film Juice Evaporator and a Sensitivity Analysis

Fresh fruit juice has a short storage period and it usually needs to be concentrated for shelf-life extension. Evaporation of fruit juice is an attractive method and vertical tube falling film evaporator is one of good choice. The main problem in the design of the evaporator is the reliable estimation of the heat transfer coefficient for all effects. In this paper, the effects of feed flow rate, evaporation temperature, temperature difference, and juice soluble solid content on heat transfer coefficient of a vertical falling film evaporator were investigated. The Bayesian treed Gaussian process model was used to identify the key variables affecting the heat transfer coefficient, which showed that evaporation temperature had the greatest influence on the sensitivity of heat transfer coefficient. It also demonstrated that complex interactions existed between the four operating parameters had a significant effect on the overall heat transfer coefficient.