Calculation of frictional resistance for brick or concrete ducts

The air temperature and absolute roughness are key factors affecting frictional resistance of brick or concrete ducts for pressurization air supply systems and exhaust smoke systems in highrise buildings. Calculation results show that when a deviation occurs in actual air temperature and roughness from the designed value, there will be a distinct difference between the design and actual frictional resistance, and the error will exceed the allowed value specified in related codes, and thus the system operation can not meet the design demand.