Standard Energy Flow Analysis Of Central Air-conditioning System With Air-cooled Chiller

In the process of operation of central air-conditioning systems,many energy flows(such as cold loss of water and air transport systems;the energy loss which is caused by inefficiency of pumps,fans,etc.)have a very important impact on running energy consumption,cost and other technical and economic indicators of the entire air-conditioning system,has attracted wide attention.But because of the lack of a standard to quantitative analysis,so a long time on the study of this problem has remained in the qualitative analysis of the stage.The operation of the existing energy-saving most studies only focused on the monomer of energy consumption equipments and each component,rarely on each part after the combination system of the overall energy-saving running effect.Most of the existing energy-saving researchs are only focused on the energy-consuming equipments and components of air-conditioning system,and rarely involve the overall energy-saving operation of the system.A complete central air-conditioning system is composed of a lot of sub-loop,which seem to be independent of each other,in fact,is a tightly integrated overall.The operation of energy consumption and energy-saving potential analysis is indeed affect the whole system.Moreover,since the energy consumption standard of the central air conditioning systems have not yet been established,it is impossible to quantitatively analyze the influence of the energy flow factors on the overall energy consumption of the central air-conditioning systems.And it can not correctly understand the maximum energy saving potential of the central air conditioning systems,resulting in long-term energy saving measures did not achieve the desired results.In this paper,the central air-conditioning system with air-cooled chiller is taken as the research object.From the global and overall point of view,the standard energy flow diagram analysis method of such central air-conditioning system is constructed.In this method,the sub-loops and components are included in the system,and provides a comparative standard,which can quantitative analysis for the operation of central air-conditioning system which is deviating from the standard energy flow diagrams.The main work is as follows:1.Through the establishment of central air-conditioning systems with air-cooled chiller energy flow chain,a complex air-conditioning system is reduced to four different energy flow loops,and with the help of the research method of Sankey diagram which is used to analyse the complex systems of energy flow process,the running energy flow diagram of central air-conditioning systems with air-cooled Chiller is established.Based on the concept of energy consumption in the construction field,the concept of energy consumption of air-conditioning systems whit air-cooled chiller is put forward,and the standard energy flow diagram of this system is established,thus provides a standard the of energy saving potential of air-conditioning systems;2.Through study relationship between the total running energy consumption intensity of the air-conditioning systems with air-cooled chiller EI(the energy consumption of the unit cooling air-conditioning system provided to the air-conditioning area)and the energy consumption between the flow rate of the fluid flow unit e and the conveying flow p.The construction of e-p analysis method of the total running energy consumption,it is provided a theoretical basis to quantitative analysis of air-conditioning systems deviation from the standard energy flows on the total energy consumption of the systems;3.According to the results of 1 and 2,based on the types of energy flows,the influencing factors in the energy flows of each unit will be divided into three categories,which will lead to the deviation of the energy flows of the air-conditioning systems: The basic energy-consuming equipment inefficient,the cold loss of pipe which is caused by insulation not tightly and heat transfer efficiency of heat transfer equipment inefficient air-conditioning systems energy consumption increased.The influence of energy influencing factors on the energy flows and energy consumption of the air-conditioning systems is analyzed quantitatively.the influence relation between e and p and the energy flow diagram which influencing factors are deviated from the reference condition are established.So as to construct the reference energy flows analysis method of air-conditioning systems with air-cooled chiller.4.In case study,the operational energy consumption of the typical air conditioning system of an office building in Guangzhou is verified and inspected to analyze the energy flow analysis method.The conclusion is as follows:(1)The energy efficiency of the refrigerant loop and the outdoor heat exhaust loop are the lowest,the energy saving space is the biggest,and the inefficient of cooling unit causes the maximum increase in energy consumption of the air-conditioning system,the increasement of the energy consumption is 114.615 kW.(2)The heat loss of the chilled water pipes and the inefficient of terminal fans led to the smallest increase on energy consumption,it can be ignored.(3)The lower the efficiency of the equipment,the more obvious the increase in energy consumption under the standard condition,followed by the chilled water pumps> refrigeration compressors> terminal fans> condenser fans,and the greater energy base of the equipments,the greater amount of change in energy consumption and energy intensity of air-conditioning system,followed by the refrigeration compressors> condenser fans> chilled water pumps> terminal fans.So as to guide the analysis of specific engineering energy-saving potential,promote the application of theory in engineering practice,give full play to their guiding role.