Comparison study of thermal comfort and energy saving under eight different ventilation modes for space heating

The relative location of inlets and outlets plays an important role in thermal comfort and energy conservation under ventilation modes for the building non-uniform indoor environment.Hence,a comparison study of thermal comfort and energy efficiency of eight widely-used ventilation modes for space heating was conducted in this study.Both subjective experiments and verified computational fluid dynamics(CFD)models were carried out.In the subjective experiments,the vote of local thermal sensation(LTS),overall thermal sensation(OTS)and draft sensation were collected.In the CFD simulations,RNG κ-ε model was applied to compare and analyze the air temperature field,turbulence intensity,ventilation effectiveness and air diffusion performance index(ADPI).The thermal comfort results showed that the air inlets are better located at the mid-height level of a wall,and the outlets are located at the same or higher height.While the results of the energy efficiency suggested that the inlets are better installed at the lower level of a wall,and the outlets should be placed far from the inlets.Since the results were conflict,the economic-comfort ratio was introduced to calculate and compare the thermal comfort and energy efficiency simultaneously.The final results concluded that it can achieve excellent thermal comfort performance without sacrificing energy efficiency when the inlets are at the height of 1.2 m of the front wall,and the outlets are at 1.2 m height of the back wall.Hence it is the best choice for the winter air distribution in northern China.This study can offer a guideline for the air terminal arrangements in non-uniform ventilation under heating mode.