Simulation And Experimental Study Of Distributed Heating And Air Conditioning System Based On Heat Source Tower

In order to meet the needs of modern users for independent start and stop of each area of the new air conditioning system,while ensuring that the cold and heat sources used are green and efficient,this paper constructs a new type of air conditioning system—a distributed heat pump system based on heat source tower.The system combines the advantages of the heat source tower heat pump and the decentralized terminal,which not only inherits the advantages of high energy efficiency of the heat source tower heat pump,but also has the characteristics of flexible installation and independent control of the decentralized terminal,and has great research value and development potential.On the basis of predecessors,this paper carried out the following research :Firstly,this paper constructs the experimental platform of the distributed heat pump system,and introduces the main composition and operation principle of the experimental platform.In order to obtain the operating law of distributed heat pump system in winter and summer through experiments,the corresponding experimental methods,winter and summer experimental conditions and system performance indicators are formulated.At the same time,the uncertainty analysis of the system performance indicators and the energy balance analysis of the whole system operation are carried out to ensure that not only the data accuracy meets the requirements,but also the adiabatic performance of the system is good,which improves the reliability of the experimental test results.Secondly,this paper studies the operation law of distributed heat pump system in winter and summer,and analyzes the essence of heat and mass transfer in winter and summer.The experimental results show that : in winter,the system performance coefficient increases with the increase of outdoor air temperature and relative humidity,inlet air flow rate and solution flow rate of the heat source tower,and inlet solution concentration of the tower.The influence of air temperature on COP is larger,and the influence of solution concentration is smaller.COP increases first and then decreases in the process of starting ratio decreasing from 100 %,and reaches the maximum 4.1 at 71.7 %.In summer,the system performance coefficient decreases with the increase of outdoor air temperature and air relative humidity,and increases with the increase of inlet air flow and inlet water flow of the heat source tower.The influence of air relative humidity on COP is greater.COP increases first and then decreases in the process of starting ratio decreasing from 100 %,reaching a maximum of 4.5 at 72.4 %.Then,a distributed heat pump system is installed in an office building in Changzhou,and the engineering performance of the system is tested.The main conclusions are as follows: after the installation and operation of the system,the annual indoor temperature range of the building is basically between 10 °C and 30 °C,and the relative humidity range is basically between 30 %and 90 %.Both winter and summer reach the thermal comfort level II,which proves that the system has good performance in creating indoor thermal and humidity environment and high comfort.According to the monitoring results and the model calculation,the energy efficiency ratio of the heating season is 3.10,the energy efficiency ratio of the cooling season is 4.30,and the annual comprehensive seasonal energy efficiency ratio is 3.83,which proves that the system performs well in energy efficiency and has high energy saving potential.Finally,in order to supplement the missing operation data affected by the epidemic,the mathematical model of the system is established and verified.On this basis,it is compared with other conventional air conditioning systems to reveal the energy saving principle of the system.After selecting two typical days in winter and summer for research,it is found that : compared with the VRV system,the distributed heat pump system has no frosting problem in winter,and the heat transfer efficiency of water-cooled system is higher than that of air-cooled system in summer.The COP of the distributed heat pump system is 17.4 % higher than that of the VRV system under the same working conditions throughout the year.Compared with the heat source tower heat pump system,the performance of the distributed heat pump system is improved under partial load.At the same time,due to the direct heat transfer between the refrigerant and the air in the indoor side,the heat transfer temperature difference is small,and the COP of the distributed heat pump system is 6.7 % higher than that of the heat source tower heat pump system under the same working conditions throughout the year.