Optimization Research On Air Conditioning System Of An Office Building In Ningbo City

HVAC system is one of the main sources of Building energy consumption, the proportion of its energy consumption is more than 50%. In order to achieve the purpose of building energy efficient, the research of the HVAC system has become a hot research topic.As the policy of the electricity demand response has proposed, the energy-saving building should also realize the purpose of cost-saving.Therefore, in order to ensure the air conditioning systemof existing buildings energy-saving, as well as cost-saving, it practically important to study on the system according to the electricity demand response.In this paper, Ningbo Institute of Technology, Zhejiang University in Ningbo City of Zhejiang Province is chosen as the research object. The total air conditioning area of the building is 9187.05m2, and the cooling load index is 95W/m2. The main research contents are as follows:(1)The annual dynamic cooling load of the air conditioning system in the building was calculated using an energy consumption simulation software,De ST. Then the cooling loadvalue of special day in July 21 st was deduced.(2)The chilled water supply temperature, chilled water flow rate and condensation side air volume were chosen as optimized variables and the consumption model of equipments in the air conditioning system and the constraint conditionswere established according to the characteristics of the actual system, so that the optimization model of the system wasestablished.(3)The optimization model of the typical day of air conditioning system were solved by using real-coding genetic algorithm through the MATLAB software, then the energy-saving scheme of air conditioning system was obtained.(4)Pre-cooling scheme of the buildingfor cost saving was introduced according to energy storage measures for electricity demand response. On the basic of time-of-use rates of Ningbo City, the whole cost of energy-saving scheme and the cost-saving scheme was calculated and compared.The electricity cost of two schemes was processed according to the optimization conclusions and the time-of-use rates. The results show that the total energy consumption of air conditioning system is 1578.86 k W, and it is 13.24 percent less than the average energy consumption in normal time,which is 1819.70 k W;the cost of cost-saving scheme is 1509.403 CNY and the energy-saving schemeis 1561.641 CNY. The savings rate of the energy-saving scheme is 5.49%, and the cost-saving scheme is 8.65%. The research in this paper provides suggestions for the economic operation of air conditioning system in the building, and it has provided reference for the system operation optimization and design of the air conditioning system in the similar building.