Semi-laboratory scale investigation of energy efficiency of masonry wall drying process by applying a thermo-injection method

Abstract

Excessive wall dampness causes damage to buildings, increases energy consumption for heating and cooling, and favors breeding microorganisms dangerous for people's health. In that case, moist walls must be dried and renovated, including making them waterproof. However, present methods for drying are highly time- and energy-consuming and its optimal implementation should be searched. This paper investigates the behavior of wet masonry wall specimens during the drying process in the semi-laboratory scale. The study aimed to examine the influence of different operating parameters of the considered masonry wall drying method on samples' drying rates and propose an optimal drying strategy. Small-scale masonry wall samples made of red ceramic bricks, cement-lime binder, and plaster were considered. Specimens had similar dimensions of approximately 1000×1000×600 mm and a dry mass of roughly 1050–1150 kg. Two types of constructions were studied, i.e., plastered and unplastered. The drying process was conducted by applying the thermo-injection method and using a dedicated device that ventilated and heated the wet sample. Different drying device operating conditions and drying process implementations were tested, i.e., single-phase drying without and with heating for two constant mass flow rates of drying air and two-phase drying initially without and then with heating and with two different mass flow rates of drying air. Moisture mass change in the wet specimen, temperatures in several locations in the sample, relative humidity and temperature of the surrounding air in the room, as well as the drying device electrical parameters, were monitored to have insight into the drying phenomenon and assess the energy efficiency of the process. In both tested constructions, the lowest amount of energy was consumed during drying with ventilation mode on and without heating. However, much less moisture was removed from samples in these implementations than for drying implementations with heating. The drying with heating mode activated showed the highest moisture removal efficiency, but energy consumption increased significantly. The drying strategy with a two-phase drying process, i.e., initially without and later with heating of the specimen, showed promising efficiency and a good perspective for the future optimization of the process.