Performance analysis and energy saving potential of air conditioning system in semiconductor cleanrooms

Large energy consumption of air conditioning system occurs in semiconductor cleanrooms due to high demand for the control of temperature and humidity ratio. This study focuses on the operating performance and energy saving potential of the air handling process. On-site measurements of the air conditioning system were conducted in different seasons. The results reveal that cold-heat offset problem occurs in the current air conditioning system in summer, including 41.7% cold-heat offset between the heating in the make-up air unit (MAU) and cooling in the dry cooling coil (DCC), and 16.4% cold-heat offset in MAU. Feasibility of removing reheating in summer is simply verified. In winter, DCC has the potential to recover in door heat for preheating the outdoor air. Therefore, high temperature chillers (Method A), canceling reheating (Method B) and heat recovery design from DCC system to MAU (Method C) are the energy saving methods adopting in this study. In order to analyze the annual energy saving potential of the proposed system, a dynamic calculation model is established. Cooling in DCC (Q(c,DCC)) is 42.8%-54.1% less than the current system annual. Heating in MAU (Q(h,MAU)) is 52.8%-94.3% less than the current system in transition season and winter (Nov.-Apr.), and is no required in summer (May-Oct.) in the proposed system. The proposed system can save 621 kWh/m(2) annual, which is 20.2% less than the current system. It is indicated that both removing reheating and adopting heat recovery system in the current cleanrooms have certain energy saving significance.