a b s t r a c t
An optimal control strategy for minimizing the energy consumption of variable refrigerant
flow (VRF) and variable air volume (VAV) combined air conditioning systems was presented.
The combined system was proposed to take advantages of VAV systems to solve the
ventilation problem of VRF systems. The VAV part consists of an outdoor air processing unit
and air supply and distribution devices. To determine set-point of the optimal control variable,
i.e. outdoor air supply temperature, this paper proposed an optimal control strategy
based on adaptive predictive model and recursive least squares estimation technique.
Typical days in summer and winter were selected to test the strategy. Results indicated that
the optimal control strategy reduces energy consumption of the combined system by 32.17%
in summer and 2.47% in winter. The overall energy efficiency is enlarged by 12.18% in
summer and 3.37% in winter, compared with the benchmark operation strategy.
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