Abstract
In order to find out efficient local ventilation method for airtight houses, experimental study was conducted using commercially available gas range and compensating hood. At the first stage of study, airflow and temperature profiles of thermal plume over the range were measured without operating range hood. From the thermal plume experiments, it was found that the velocity and temperature profiles become almost similar irrespective of heat input, and the entrainment velocity of thermal plume is small and less than 10 cm/s. Then, air inlet was installed at different flow directions to estimate diffusion effect of fresh air supplied close to the range. The results suggested that fresh air supplied downward from hood level can significantly diffuse thermal plume, fresh air tends to reduce exhaust flow capture ratio and upward flow from range level exerts relatively small influence to the thermal plume. At the main part of the study, capture efficiency of the compensating range hood was measured at different supply and exhaust air volume. The results are summarized as follows.
I) capture ratio of the compensating hood depends on the supply flow rate ratio, and is nearly constant if supply flow rate ratio does not exceed certain maximum value.
2) short cut ratio of the fresh air depends small on the supply flow rate ratio and decreases for larger supply flow rate.
3) exhaust flow volume of tempered air can be significantly reduced if supply and exhaust air flow rates are optimally balanced.
