Impact of personal factors and furniture arrangement on the thermal plume above a sitting occupant

The impact of thermal insulation and the design of clothing and chair, the blocking effect of a table and breathing on the thermal plume above a sitting thermal manikin was studied in a climate chamber. Air speed and temperature in the plume cross-section 0.7 m above the manikin head were measured. Results show that loose clothing increases the volume flux by 24%, changes the shape of the plume and thus should be carefully simulated.

Tight clothing and chair design do not affect the plume volume flux and need not be considered in full-scale experiments. However, the convective part of the sensible heat loss increases with thermal insulation of a chair, and may be important in detailed CFD predictions. A wig on the manikin head appears to be important because a bald head decreases volume flux by 15%.

Positioning the table tightly in front of the body affects air temperature and velocity distributions in the plume and increases volume flux by almost 50%. Exhaling through the mouth expands the plume, resulting in the integral characteristics being 40% greater and therefore should be considered in numerical simulations or experiments with thermal manikins, while exhaling through the nose can be disregarded.

The volume flux of the thermal plume 0.7 m above the head of a sedentary occupant can be calculated with 25% uncertainty, using values for the convective heat loss equal to 30% of the sensible heat generated by the body and the distance of the virtual plume origin equal to −1.60 m.