Simulation And Optimization Of Air Conditioning System With Liquid-separation Condenser

Heat pumps and air-conditioning systems consume about 30% of the total energy in society.How to improving the energy efficiency of air-conditioning systems and reducing energy consumption are the main focus of research.The liquid separation condensation technology is a new type of enhanced heat transfer technology that can increase the heat transfer coefficient of the condenser and reducing the pressure drop of the refrigerant simultaneously.It also can improve the energy efficiency ratio of the system.At present,the research on air-conditioning system with the liquid-separation condensation is mainly carried out by experimental tests.This research establishes a model of air-conditioning system with the liquid-separation condensation and studies the influence of the structure of the liquid-separation condenser on the performance of the air-conditioning system.Firstly,the steady-state system simulation model of the liquid-separation condenser,evaporator and capillary tube is established by using the distributed parameter method.The compressor theoretical model is established,and then air conditioning system model is integrated.Further experimental research is carried out to verify the simulations.The results show that the prediction results of the models are in good agreement with the experimental data,and it is further used for the performance research of the liquidseparation condensation air-conditioning system.Secondly,the influences of the arrangement of the tube path of the liquid separation condenser,the fin spacing and the longitudinal spacing of the heat exchange tubes on the performance of the system are studied by using the model of the liquid-separation condensing air conditioning system.The results show that air conditioning system with a tube pass arrangement of 6-5-4-3-3-1-1-1 in the liquid-separation condenser has a maximum energy efficiency ratio of 3.51.Under the optimal tube path,the system energy efficiency ratio is as high as 3.9 when the fin spacing is 1mm.Under the optimal tube path and fin structure,when the heat exchange tube spacing is 24 mm,the system energy efficiency ratio is the largest.Compared with the air-conditioning system with liquidseparation condenser used in the experimental test,the energy efficiency ratio has been increased from 3.34 to 3.92.So far,based on the highest energy efficiency ratio of the system,the optimal structure of the liquid separator is obtained.Finally,using the optimal structure of the liquid condensing air-conditioning system,the performance of the system under the variable indoor wet bulb temperature,the variable outdoor dry bulb temperature and the actual cooling operation time of ten cities are respectively studied.A 6°C increase in indoor wet bulb temperature leads to an increase in system energy efficiency ratio from 3.43 to 3.86;a 6°C increase in outdoor dry bulb temperature leads to a decrease in system energy efficiency ratio from 3.99 to 3.46.The maximum difference of system seasonal energy efficiency ratio between the national standard calculations and the actual cooling operation time in various places is only 4.1%.Through the system simulation program,the optimal structure of the sub-liquid condenser is obtained and the performance of the optimal system under variable conditions is studied.It shows that optimizing the structure of the liquid-separation condenser can significantly improve the system performance.The simulation model is used to optimize the liquid separation condensing air-conditioning system,which has the advantages of saving money and time,and can also optimize some structural parameters that are inconvenient for experimental testing.