Latvia, jointly with other European Union member states has undertaken to significantly increase renewable energy proportion in final energy consumption, increase energy efficiency and reduce greenhouse gas emissions. In order to achieve it with limited resources during the economic recession conditions, particular importance is for quick implementation of cost-effective scientific production solutions, which is the main motivation and benefit of this work. About a third part of heat energy produced in the district heating boiler houses in Latvia, is extracted from the local wet wood chips with high moisture content, on average, about 40%. It means that in order to burn 1 tonne of fuel into the atmosphere through the chimney is vaporized and discharged about 400 kg of water. The aim of the Thesis is to develop and research industrial model of a flue gas condenser, to perform heat and mass exchange process modeling in apparatus for recovering consumed energy for the water vaporization. The following research objectives for achieving the aim of the work are proposed: • mathematical description of the heat and mass exchange processes in the gas condenser evaporation and condensation part; • to develop a mathematical model of the gas condenser and to create computer modelling on its base; • to perform industrial experiment to gain empirical model of gas condenser performance parameters interaction; • to perform data analyses obtained during modeling and industrial experiment and to develop proposals for gas condenser operating efficiency. In Thesis is developed a direct contact gas condenser industrial experiment planning and data processing method and set up the equipment for heat and mass exchange process model. Company “Komforts” has manufactured experimental model of flue gas condenser, which successfully operates at Ludza town district heating system. The developed system is an important step in use of efficient renewable energy resources in the Latvia’s and European energy sector. Results of the work have a practical importance in national, regional and local levels. In any of the existing woodchip boiler houses burning wood chips, can be installed gas condensers and the energy consumption could be reduced by up to 20%.