Sukhodub I. Energy processes in ventilation system cross-flow recuperative heat exchanger

Thesis is devoted to the analysis of energy processes in the cross-flow heat exchanger membrane recuperative ventilation systems for the climatic conditions of Ukraine. Mathematical modeling of heat transfer in laminar flow for parallel plates channels with and without fins of triangular and square cross-section is carried out. A method of local heat flux calculating with the variable wall temperature, which is typical for cross-flow, is proposed. Model for heat and mass transfer processes in the cross-flow heat exchanger is improved, considering condensation and frost formation processes, including the development of these processes in time. An experimental study of the membrane water vapor permeability coefficient is done on the gravimetric method basis. Using experimental data average energy efficiency coefficients are calculated for heating and summer periods under real weather conditions in Kiev. Possible short-circuits inside the unit are analyzed and the correction of experimental data is performed. The analysis of meteorological data for energy calculations of ventilation systems with heat recovery selection and averaging is done. Methodology for conducting a technical and economic analysis is improved for heating and summer periods. A long-term exergy analysis of heat recovery unit and whole ventilation system is carried out on the basis of typical meteorological year IWEC for Kiev. Specific exergy components for heating and summer periods and exergy efficiency coefficients are analyzed.