A study of kitchen range exhaust systems

Investigations were carried out on wall-mounted overhead, island, and downdraught kitchen fans. Energy consumption, airflow ratings, and velocity profiles were measured. Flow fields were studied by flow visualization, and effects of adding side baffles, perimeter slots, visors and varying hood heights were studied. Side baffles increased the capture efficiency of overhead hoods. Capture efficiency was also improved by decreasing clearance height. Downdraught systems were effective only for low cooking pots. Air flow velocities were measured using an omnidirectional hot wire probe and were found to decrease rapidly with increasing distance from the exhaust opening. A simple potential flow model was also used to calculate air flow velocities and results compared well with measured values. The three ventilation systems were rated for sound by measuring fan output noise. (from authors' abstract)