Pressure and flowrate distribution in central exhaust shaft with multiple randomly operating range hoods

Central flues are now commonly adopted in high-rise residential buildings in China for cooking oil fumes (COF) exhaust. Range hoods of all floors are connected to the central shaft, where oil fumes were gathered and exhausted through the outlet at the building roof. As households may cook and use their range hood at random periods, there is great uncertainty of the amount of COF being exhausted. In addition, users can often adjust the exhaust rate of the range hood according to their needs. As a result, thousands of possible operating conditions consisting of distinct combinations of on/off conditions and fan speed occur randomly in the central COF exhaust system, causing the exhaust performance to vary considerably from condition to condition. This work developed a mathematical model for characterizing the operation of the central COF exhaust system in a high-rise residential building as well as its iterative solving method. Full-scale tests coupled with CFD simulation referring to a real 30-floor building were conducted to validate the proposed model. The results show that the model agreed well with the CFD and experimental data under various system operating conditions. Moreover, the Monte-Carlo method was introduced to simulate the random operating characteristics of the system, and a hundred thousand cases corresponding to distinct system operating conditions were sampled and statistically analyzed.