The flash evaporation process uses pressure differences to cause instantaneous fluid cooling and concentration. It is thus used for shortened cooling time in the wine-making process. Although promising since it allows grape cooling and concentration in addition to improving wine quality with one single device, the development of this process remains limited because of the poor efficiency of the thermal exchanges and the important size of the installations. The preliminary design stage is one of the first steps of the design process. Often neglected, this stage is nevertheless important since decisions taken at this point, like gauging and choosing components, are of major importance in relation to global development costs. In order to improve the system compactness and thermal efficiency and, to support the decision-making process, a multicriteria and multiphysics-oriented preliminary design of an innovative two-stage flash evaporation process for cooling in wine-making process was performed. Using a specific formalisation methodology that uses Constraint Satisfaction Problem techniques to enable taking into consideration different types of data, constraints related to the physical behaviour of the system and to manufacturing, encumbrance, eco-design and cost criteria are simultaneously included in the design model. The entire physical model, considering multiple coupled phenomena, was validated through an experimental analysis carried out on an instrumented pilot unit. Results are presented and discussed. Global results, considering physics, gauging, mass, costs and eco-design constraints are also presented and discussed. A detailed design flash evaporator specifically for industrial use is briefly described. (c) 2007 Elsevier Ltd. All rights reserved.