Analysis of seasonal energy consumption during drying of highly saturated moist masonry walls in polish climatic conditions

Abstract

An impact of various levels of ambient air temperature and moisture content on a masonry wall drying process by applying the thermo-injection method was examined by applying numerical modeling. The new non-equilibrium model of heat and moisture transfer, developed and verified in the previous study, was used to carry out numerical experiments. One week of drying process was simulated. Drying air parameters, i.e., different relative humidities typical for four seasons in Poland (i.e., in the range of 70–90%) as well as its five different temperature levels (i.e., 20, 30, 40, 50 and 60°C) were analyzed. The key parameters monitored were the energy consumption required for the drying of building material as well as energy efficiency and entropy generated in the process. They were expressed as a function of water mass fraction in the wall to compare different parameters of the drying process. The obtained results indicated significant dependence of energy consumption in the process on parameters of drying air, i.e., temperature and humidity ratio. Higher temperatures and lower humidities levels allowed to reach lower final moisture content in the wall. But, during the first drying period, i.e., first 24 h, drying rates were found much higher than later and weakly dependent on the air temperature. The drying process was efficient even though low air temperature was used. But later higher air temperatures were required for efficient moisture removal from the wall. This observation suggests applying various drying air temperatures which in turn may allow for reduction of energy consumptions during drying of masonry walls.