Research On Energy Saving Control Strategies Of VAV Systems Under Full Year Operation Conditions

With the development of economics, people has put forward higher requirements on HVAC systems, including indoor environment, energy saving and environment protection. Now HVAC systems are becoming more and more complicated and their automation systems are gradually perfected. How control strategies can meet people's requirements has become the mainstream of related researches. However, too many control loops may cause the system tedious and increase the control and tuning difficulties in future, it's necessary to adopt appropriate control strategies considering the main factors that influence the energy consumption.Some parameters of the indoor environment, such as the indoor temperature, relative humidity, supply air temperature and fresh air volume, are the basic goals that each HVAC system should achieve, so the related control strategies have been an important part of researches about control strategies of HVAC systems. These can not only ensure a comfortable indoor environment, but also the energy consumption systems. HVAC system is a dynamic open system, influenced by climatic parameters, indoor conditions and building types. Different control strategies in different conditions can cause different results. Now research on the variation of relevant indoor parameters, as well as energy consumption, indoor air quality and thermal comfort with control strategies under a whole year has become an important issue.Through BIN and regression analysis, energy consumption has been calculated rapidly and the main factors that influence the HVAC energy consumption are as follow: the occupancy, internal load, indoor temperature and outdoor air volume standard. In this paper, we put forward these control strategies, indoor temperature reset, minimum fresh air control based on dynamic occupancy detection and economizer cycle combined with supply air temperature reset, which are tested and validated with a whole year on TRNSYS simulation platform. The results show that: the indoor temperature reset control is the most energy-efficient strategy, but it deteriorates the indoor thermal comfort; minimum fresh air control based on dynamic occupancy detection can also save energy, however the indoor air quality have been affected; although the energy saving potential of economizer cycle combined with supply air temperature reset control is small, a marked improvement of indoor air quality in transitional seasons have been achieved.