Research On Performance Test And Energy Saving Control Optimization Of Refrigeration Room System In Public Buildings

With the development of the global economy,the total global energy consumption and carbon emissions are increasing,and for this reason,vigorously advocating energy conservation,emission reduction and green living has become the focus of attention worldwide.Under the impetus of the dual carbon strategy policy,energy saving in buildings has been paid more and more attention.At present,the whole life cycle of building energy consumption in China accounts for more than 50% of the total national energy consumption,of which public buildings account for about 33% of building energy consumption,while HVAC system energy consumption accounts for more than 60% of public building energy consumption.As a major energy consumer in public buildings,due to the design stage is in accordance with the maximum cold load for air conditioning system equipment selection,and in the actual operation of the system is often in part-load operating conditions,coupled with the operation process without the relevant measurement devices,manual management of crude,improper control strategies lead to high energy consumption of the air conditioning system,the status quo of serious energy waste.Therefore,it is crucial to improve the cooling efficiency of air conditioning systems to achieve energy saving in buildings.This paper studies the operational characteristics and energy consumption of a central airconditioning refrigeration room system in a shopping mall in Xi’an with a floor area of 123,000m2,and proposes optimal control strategies for the problems existing in the operation process.Firstly,the current status of research on refrigeration rooms and energy saving control strategies in public buildings is introduced.Then,according to the actual measurement data of the shopping mall,the cooling capacity,motor loading rate,freezing side and cooling side convergence temperature of the three large centrifugal chillers were analyzed,and it was found that the No.3 large chiller had better cooling performance and longer operation time.From the operation characteristics of the system equipment in the whole cooling season,the unit cooling capacity,power consumption,energy consumption of the transmission and distribution system,comprehensive system energy efficiency ratio and delivery coefficient were calculated,and the results showed that the average COP of the chiller unit was 6,the comprehensive system energy efficiency ratio EER was 4.5,the average delivery coefficient of chilled water WTFchw and the average delivery coefficient of cooling water WTFcw were 48 and 49.2,the average delivery coefficient of cooling tower coefficient WTFct is 118,and the energy consumption on the transmission and distribution side accounts for about 23.6% of the total energy consumption.At the same time,it is pointed out that the system has the operation status of large flow rate and small temperature difference,and the chiller plant is not in its energy-efficient operation range.In order to further improve the energy efficiency ratio of the system,a dynamic model of the system is established in this paper using the TRNSYS simulation platform.Firstly,De ST simulation software is used to simulate the summer cooling load of the building,and a cooling load prediction model is established by multiple linear regression based on different meteorological parameters,and the correlation between the influence factors of meteorological parameters and the cooling load is analyzed.Secondly,this paper combines some actual operation data and sample data provided by the manufacturer to establish mathematical theoretical models of each air conditioning system equipment and perform parameter identification fitting.Finally,this paper inputs the summer cooling load of the building and establishes the simulation model of each system equipment using TRNSYS,builds the simulation simulation platform,and verifies the accuracy of the model using the actual operation data and simulation data.It was verified that the time-by-time mean deviation(NMBE)and mean squared coefficient of variation(CV)were obtained within ±10% and ±30%,respectively,and the errors were within the allowable range,which proved the reliability and accuracy of the system model.Finally,by analyzing the energy consumption of the current air conditioning system,this paper proposes an optimal COP allocation control strategy based on the efficient operation interval of multiple chillers,as well as two operation strategies of unit-by-unit start-up control and load-sharing control for system energy consumption and energy efficiency comparison.At the same time,the comparison of energy consumption between variable and constant temperature differential flow rate on the cooling side under the operation condition of "large flow rate and small temperature differential" on the transmission and distribution system side is analyzed,and the optimized control strategy of large temperature differential variable flow rate is proposed when the building load rate is high on the basis of the COP optimized allocation strategy in the combined operation of chillers.Through the analysis of the simulation results,it is found that the use of the optimal control strategy can effectively reduce the system energy consumption.Compared with the existing operation strategy,the optimal control strategy can improve COP by about 2.1% and EER by about 3.95%.Although the use of a large temperature difference and variable flow rate on the cooling side has a certain impact on the COP of the unit,the energy consumption of the system on the transmission and distribution side is reduced,and the overall energy consumption also shows a decreasing trend.During the whole cooling season,the system is able to save 98,310 k Wh of power consumption,which is 9.3% energy saving compared with the original system management mode.Through simulation,the COP of the unit can reach 6.33 and the overall energy efficiency ratio of the system can reach 4.94.The use of this optimal control strategy can also reduce 39.32 t of standard coal,as well as 98.02 t of carbon dioxide,2.95 t of sulfur dioxide,1.48 t of nitrogen oxides and 4.01 t of smoke and carbon dust,with a corresponding environmental benefit value of $23,621.5.is $23,621.5.The research of this paper provides data support and basic research reference for the actual operation analysis and regulation optimization of the refrigeration room system.