NUMERICAL SIMULATIONS OF FLOWS IN PUSH-PULL FUME CUPBOARD

A push-pull fume cupboard shown is an innovative device to remove pollutants from a fume cupboard to the outdoor environment. A push flow coming from the bottom of a sash and a pull flow behind the doorsill are adopted to form an air curtain in the fume cupboard. Meanwhile, the roof of a push-pull fume cupboard is open to the environment and ambient fluids are drawn from the roof. To investigate the performance of a push-pull fume cupboard, a numerical model based on the finite volume method is utilized. Various ratios of push flows to pull flows are considered. Four characteristic flow fields are found at a variety of speed ratios. They are concave curtain, straight curtain, under suction and over blow modes. According to numerical results, a concave curtain mode with a fast pull flow and a weak push flow is recommended for the operation of a push-pull fume hood. Furthermore, the manikin effect on the flow filed of a push-pull fume hood is also examined in this study. A manikin is located in front of the fume cupboard according to the ANSI/ASHRAE 110/1995 standard. Numerical results reveal that fluid flows in a push-pull fume cupboard are not affected by a manikin. As a result, an operator standing in front of a push-pull fume cupboard is protected from pollutants inside the cupboard