Heat removal efficiency based multi-node model for both stratum ventilation and displacement ventilation

Publication date: 1 October 2018
Source:Building and Environment, Volume 143
Author(s): Sheng Zhang, Yong Cheng, Chao Huan, Zhang Lin
The non-uniform distribution of vertical air temperature helps stratum ventilation and displacement ventilation to save energy compared with mixing ventilation. To reasonably predict the vertical distribution of the non-uniform air temperature, the multi-node (nodal) model requires an in-depth understanding of the airflow pattern and is specific for different designs of ventilation, which challenges engineers/designers in practice. To be more practical, this study proposes a heat removal efficiency (HRE) based multi-node model. The proposed model employs HRE to conveniently represent the airflow pattern, requiring little understanding of the airflow pattern. Moreover, the proposed model is general for both stratum ventilation and displacement ventilation, and flexible to include heating/cooling devices. Experimental case studies show that compared with the conventional model, the proposed model is more accurate and robust. The proposed model reduces the overall mean absolute error in the temperature predictions of the nodes of the air and inner surfaces of the enclosure by 0.1$°$C (from 0.94$°$C to 0.84$°$C) for stratum ventilation, and by 0.08$°$C (from 0.33$°$C to 0.25$°$C) for displacement ventilation with floor heating; and reduces the associated overall standard deviation of errors by 0.14$°$C (from 0.55$°$C to 0.41$°$C) and 0.02$°$C (from 0.19$°$C to 0.17$°$C) respectively. Benefiting from its convenience, generality, flexibility, accuracy and robustness, the proposed model is practical and would contribute to the practical applications of the energy-efficient stratum/displacement ventilation strategies.