Model-based Optimal Control of Outdoor Air Flow Rate of an Air-Conditioning System with Primary Air-Handling Unit

This paper presents a model-based outdoor air flow rate optimal control strategy for multi-zone variable air volume air-conditioning systems with the primary air-handling units. An adaptive optimisation algorithm is adopted for optimising the set point of the outdoor air flow rate to minimise the energy cost, which could compromise the energy consumption of the primary fan and the cooling energy saving by the cold outdoor air. The primary fan energy consumption can be predicted using a simplified incremental fan model and the main parameters of this model are identified online. The cooling energy saving by the outdoor air is estimated online using the enthalpies of the air streams. The lower limit of the outdoor air flow rate is determined by a CO2-based adaptive demand-controlled ventilation strategy using the dynamic multi-space equation to maintain the satisfied indoor air quality (IAQ). Tests were conducted to evaluate the performance of the control strategy applied to a practical building system in simulation environment. The results show that the proposed optimal control strategy can reduce energy consumption significantly, while maintaining a satisfactory IAQ.

[1]  M. Zaheer-uddin,et al.  Optimal control of time-scheduled heating, ventilating and air conditioning processes in buildings , 2000 .

[2]  J. E. Seem,et al.  Development and evaluation of optimization-based air economizer strategies , 2010 .

[3]  Theodore F. Smith,et al.  Evaluation of HVAC system operational strategies for commercial buildings , 1997 .

[4]  Shengwei Wang,et al.  CO 2-Based Occupancy Detection for On-Line Outdoor Air Flow Control , 1998 .

[5]  Andrew K. Persily.  Ventilation, carbon dioxide and ASHRAE standard 62-1989 , 1993 .

[6]  Shengwei Wang,et al.  A model-based optimal ventilation control strategy of multi-zone VAV air-conditioning systems , 2009 .

[7]  Na Zhu,et al.  Online Optimal Ventilation Control of Building Air-conditioning Systems: , 2011 .

[8]  Robert Sabourin,et al.  Ventilation Control Strategy Using the Supply CO2 Concentration Setpoint , 2005 .

[9]  Shengwei Wang,et al.  CO2-Based Occupancy Detection for On-Line Outdoor Air Flow Control , 1998, Indoor and Built Environment.

[10]  J. E. Janssen,et al.  Ventilation for acceptable indoor air quality , 1989 .

[11]  M. J. Brandemuehl,et al.  The impact of demand-controlled and economizer ventilation strategies on energy use in buildings , 1999 .

[12]  B. S. Davanagere,et al.  Mitigating the impacts of ASHRAE Standard 62-1989 on Florida schools , 1997 .

[13]  James Y Kao,et al.  Variable air volume system design guide , 1991 .

[14]  Shengwei Wang,et al.  Dynamic simulation of building VAV air-conditioning system and evaluation of EMCS on-line control strategies , 1999 .

[15]  M. Meckler.  Demand-control ventilation strategies for acceptable IAQ , 1994 .

[16]  P. Haghighat,et al.  Iaq and energy‐management by demand controlled ventilation , 1992 .

[17]  Shengwei Wang,et al.  Model-based optimal control of VAV air-conditioning system using genetic algorithm , 2000 .

[18]  James Y Kao,et al.  Economizer algorithms for energy management and control systems , 1984 .