Effect of thermo-compression on the design and performance of falling-film multi-effect evaporator

• Iterative strategy to solve evaporation with thermo-compression problems.
• Impact of property variability in evaporation with thermo-compression.
• MINLP optimization problem for an evaporation system with thermo-compression.
• FEVAT Software in Visual C++ for the design of evaporators with thermo-compression.

Thermo-compression is used in food evaporators to avoid thermal damage and reduce steam consumption. Thermo-compression has not been analysed in multi-effect food evaporator systems. For this study, an evaporation system for milk using thermo-compression was analysed. The proposed software, FEVAT (falling-film evaporation design), considers the optimization of the cost of the evaporation system and an iterative method to solve the balances of material and energy, design equations and a thermo-compression model. The FEVAT interface introduces thermo-physical properties of the foodstuff in function of composition and temperature. In order to determine the influence of the thermo-compression parameters in the simulation, a series of numerical experiments was proposed whereby the thermodynamic efficiency of the thermo-compressor, source of the steam recycling and the effect percent of recycle were varied, one by one. The results showed that the economy of evaporation is proportional to the percentage of steam recycling and the position of the effect that recycles the steam and inverse to the thermodynamic efficiency of the thermo-compressor. In this study the limiting conditions of the operation of the thermo-compressor were obtained that can be applied to other evaporation systems with different foodstuffs.