PERFORMANCE EVALUATION OF FLOW UNIFORMITY OF FAN-FILTER PROTOTYPES

Abstract

Haze is one of the most critical health and social issues in the region and there is a lack of first-line-defense product in the market to introduce filtered air into the enclosed naturally ventilated rooms during haze time. Therefore, fan-filter prototypes were developed and tested in a naturally ventilated laboratory to investigate the velocity uniformity of the filtered air supplied by the prototypes. The hypotheses of this dissertation are: 1. Pattern of loaded filter affects the flow pattern of filtered air and 2. Clean filter has better velocity uniformity. Objective experiments were conducted to test the hypotheses and parameters tested include air flow rate, averaged and point air velocities and noise level generated by the prototype. The prototypes were developed one after another with improved features to investigate impact of the design changes on air uniformity and noise level. Tests were carried out on each prototype without filter, with loaded and clean filters respectively. Results of both averaged and point velocity tests indicated uniformity improved with increased filter housing thickness for “without filter”. Better uniformity was also found in Prototype 1 for “loaded filter” test while results for prototypes 2 and 3 were different between averaged and point velocity tests. Additionally, order of uniformity for averaged velocity test was completely opposite to point velocity test for “clean filter” tests. Generally, air distribution was affected by filter loading condition as well as design and air tightness of prototypes. Uniformity trend was not constant all the time between the two types of velocity tests and noise level was not affected by the design changes. Future tests could be done on carbon filters and also incorporate subjective tests for further developments.