Energy Consumption Characteristics And Energy-saving Operation Strategies Of Air Conditioning Systems In Cigarette Factories

Tobacco industry is an important sector of Chinese revenue because of its huge scale,the tax revenue reached 1079.5 billion yuan in 2016,and the government paid special attention to the healthy development of the tobacco industry.But the cigarette production process needs air conditioning system to control its environment temperature and humidity.Air conditioning system contributes even 50%of the total energy consumption in cigarette factory,therefore,it is of great significance to realize energy-saving operation of air conditioning system.In order to improve the energy efficiency of air conditioning system in cigarette factory,a cigarette factory in Yunnan is choosed as the research object.The reasons for high energy consumption of air conditioning system in the cigarette factory were investigated.A hierarchical evaluation model for energy efficiency of air conditioning system was put forward,and the optimal operation strategy was studied according to the characteristics of air conditioning load in cigarette factory.Firstly,the main reasons of high energy consumption of air conditioning system were found through on-the-spot investigation just as follows:(1)The selection of pumps and fans whit much higher capacity of than which are required results in "large water flow rate,and small temperature change" and "large air volume,small enthalpy change";(2)low energy efficiency of the chiller because of its operation under partial load for a long time;(3)unnecessary cooling offset by reheating;(4)air handling process is not reasonable.Secondly,according to the operating characteristics of the air conditioning system of the cigarette factory,a hierarchical evaluation model of energy efficiency of air-conditioning system is established.Three levels include the whole air conditioning system,the air conditioning zone,each air handling unit in the same air conditioning area.These evaluation method is useful both to monitor the energy efficiency level of air conditioning,and to identify problem in air conditioning system of cigarette factory.Thirdly,the temperature and humidity load of cigarette workshop were calculated and summarized,the results showed that:most of the workshops,such as the cigarette manufacturing workshop and stick forming workshop,need to be cooled all year round and need to be dehumidification all the year round.The tobacco feed workshop needs to be heated in winter and needs to be added wet all the year round,Other workshops need to be dehumidified all year long,but the amount of dehumidification is small because their relative humidity are lower than tobacco feed workshop.Finally,based on the analysis of the air conditioning system in the whole year,and according to the composition of the existing air-conditioning equipment the energy saving operation strategy of the cigarette factory is suggested,i.e.the optimal air handling process is different from each other for the following four cases:(1)the enthalpy of fresh air is larger than the enthalpy of design state(hw>hN);(2)the enthalpy of fresh air is between the enthalpy of air supply and indoor air(hO1<hw?hN);(3)the enthalpy of fresh air is between the enthalpy of machine dew point and air supply(hO1?hW>hL)(4)the enthalpy of fresh air is smaller than that of machine dew point(hW?hL).In addition to the existing part of heating and humidifying process are also discussed.According to the law of conservation of energy,the optimization mathematical model with multiple constraints was established,and the penalty function method within the SUMMIT is utilised to obtain the optimal operation model,the calculated results were verified with the actual test,which showed an energy saving of 30%in this factory.