Modelo dinâmico do resfriador de gás de uma bomba de calor solar a CO2 pelo método de fronteira móvel

Abstract

This work proposes a mathematical model to simulate the behavior of a bi-tubular heat exchanger, with countercurrent and helical flow, which operates in a dynamic state. The heat exchanger is a water heater system, by the condensation/cooling of Carbon Dioxide (CO2) and it is component of a solar heat pump prototype, used to heat water for domestic use. A moving boundary model was built using the Fortran® programming language for prediction of the heat exchanger behavior. The CO2 flow was considered unidimensional, transient and with pressure drop. The moving boundary model was compared with experimental data of the solar heat pump prototype, obtained in studies on the solar heat pump prototype. The results demonstrated good agreement between the model and the experiments, with mean percentage error equal to 0,5% for the high pressures of the cycle and 4,8% for the water outlet temperature. Keywords: Dynamic model, Moving boundary model, CO2, Heat exchanger, Transcritical cycle.