Airflow Distribution Measurements around the Human Body Using a Thermal Manikin by Particle Image Velocimetry

The human body is a heat source in a room. As the human body has a complex shape, it is difficult to accurately measure the airflow distribution around the human body using a conventional anemometer. This study measured the airflow distribution around a thermal manikin acting as a human body by visualization and particle image velocimetry (PIV). The thermal manikin was 1700 mm in height, and its surface temperature was set to 30oC. The experiments were performed in the conditions when the manikin was seated on a chair. The ambient air temperature and wind velocity were experimental variables. The airflow distribution around the manikin was reported by considering the relationships between convection and ambient wind velocity. There were no differences in the airflow distribution around the manikin due to the ambient air temperature when the wind velocity in the chamber was set as 1.0 m/s. Hence, it was assumed that the ambient wind velocity was dominant in this condition. Various airflow distributions were formed around the manikin due to the difference between the body surface temperature and the ambient air temperature in the case where the wind velocity in the chamber was set to approximately equal to 0.0 m/s.

Review and development of the contribution ratio of indoor climate(CRI)

An indoor thermal environment is affected by various heat elements,such as heat transfer through walls,solar radiation,and heat emissions from people,lighting and equipment.To promote both local thermal comfort and building energy efficiency,demand-oriented ventilation(such as personalized ventilation)has been developed.When using this method,a good understanding on indoor temperature distribution becomes necessary.For this purpose,an index known as Contribution Ratio of Indoor Climate(CRI)has been developed through extraction from the calculation results of Computational Fluid Dynamics(CFD).This index can be used to analyze the independent contribution of each heat element to indoor temperature distribution.In this paper,a complete and detailed introduction of the CRI is given,including its basic premises,definitions,and mathematical meaning.Particularly,calculation method of the CRI in natural convection airflow fields is further developed.Two cases(forced and natural convection airflow fields)have been carried out in different scenarios,with results showing that the CRI of a heat source had higher values in the area around itself.Also,it had a larger influence range in forced convection airflow field because of the convective airflow,while relatively larger CRI values only appear in the area above the heat source in the natural convection airflow field because of the heat plume.As a useful index for understanding the form of indoor temperature field,the CRI has guiding significance for regulating air-conditioning/ventilation systems to build better indoor thermal environment.