Research On Energy-saving Of Unidirectional-flow Cleanroom's HVAC System

Cleanroom recently became an indispensable environment in the pharmaceutical, medical technology, and semiconductor industries for producing high quality and precision products. But cleanroom consumes energy more excessive, and it blocks the development of the cleanroom.Why the cleanroom use more energy include two main parts. For the sake of keeping the cleanliness of the cleanroom, more air should be sent in the cleanroom to thinning the airborn and exhaust the polluted air. The air which would be sent into the cleanroom should be treated many steps such as dehumidification, cooling, heating and so on. All these steps are to guarantee the temperature and humidity of the air in the cleanroom.This paper firstly analyzes the HVAC system and its all parts' energy using which is used in the cleanroom of high level cleanliness class. Some proposals are discussed to improve the energy efficiency of all parts of the HVAC system. Variable primary flow system technology, high chilled water delta technology and so on are combined with cleanroom's HVAC system to integrated system energy-saving.This paper then illustrates how to reduce the supply air. Use the CFD method as an assistant tool to study the air distribution of the cleanroom. We use the CFD method to study the airflow and cross-contamination in a photo resists research lab. The Reynolds-averaged Navier-Stokes equations governing the flow are solved using a finite-volume code FLUENT. The standard k-εturbulence model has been used. We alter the face velocity and the position of the FFU, and study the states of the cleanroom. From the numerical results, we found that when the face velocity of the FFU drops to 0．2m/s, the vertical unidirectional airflow could also keep well. Then we gained many testing data in the lab, such as velocity near the clean bench, cleanliness recovery characteristic and particle concentration. We compared the simulated data with these testing data and concluded the energy-saving airflow designing method of cleanrooms. We also used many testing data to analysed how to choose a fit fan system. We then researched the energy-saving of air handler. We designed a new air dehumidification system which used direct expansion cooling coil. Compared with the traditional dehumidification wheel system, the direct expansion system could save over 50% energy. This paper also illustrates other energy-saving method such as thermal recovery, condensation water utilizer, changed temperature chilled water and so on.Finally, the future research on the energy-saving of high level Cleanroom's HVAC System was prospected.