A three-dimensional heat-and-mass transfer model of a flat evaporator of a loop heat pipe has been developed for investigating heat-and-mass in a compensation chamber filled with a liquid. Numerical simulation was implemented using EFDLab (R) software package in order to predict the temperature distribution of the flat evaporator of a copper-water LHP (loop heat pipe) as well as the flow streamline and velocity field in the compensation chamber as a function of heat load. A computer simulation makes it possible to evaluate the heat exchange at the inner surface of the compensation chamber. Heat exchange data were used as a boundary condition in researching the problem of the drying effect of a wick and a transformation of the evaporating front in the active zone of the flat evaporator. (C) 2013 Elsevier Ltd. All rights reserved.