Investigation on the thermal budget and flow field of a manikin and comparison with human subject in different scenarios

Abstract

The thermal plume from a human significantly influences indoor air flows, impacting the dispersion of air constituents and consequently affecting indoor air quality. This is also relevant in the transport of respiratory particles, which results in spread of respiratory diseases including COVID-19 caused by SARS-CoV-2. Our focus is on the sitting condition, a common scenario in various ventilated spaces. Prior human thermal plume studies employed predominantly anemometers to measure flow field which lack spatial resolution and detailed flow field. Here, Particle Image Velocimetry (PIV) is utilized to directly visualize and analyze the human thermal plume. No direct comparison of thermal manikin and real human subject is considered in previous studies. Such experiments were performed with a thermal manikin and comparisons were made with a real human. The results show that the thermal plume from manikin without breathing function and the real person have similarities including bi-lobe structure of the flow field. The integral fluxes like volumetric flux, momentum flux, buoyancy force flux, and enthalpy flux were determined and compared. The average volume flux of real person and the thermal manikin was found to be 153 m3/h and 125 m3/h, respectively. The momentum flux was 0.005 N for both the cases. The estimation of enthalpy flux revealed that radiative heat transfer dominates and less than 50 % of the total flux is convected in the human thermal plume. In addition, a zonal simulation model was created and the volumetric flux was determined by simulation and is compared to the measured values.