The Simulation Experiment Research Of Marine Air Conditioning System Based On VAV And VWV

Ocean-going vessels are sailing in various sea areas around the world.The external environment temperature fluctuates widely in different sea areas.When the ship is in a relatively hostile environment,the operational efficiency of traditional ship air-conditioning systems will be low,and the requirements of the cabin comfort cannot be met.This paper builds a seawater-source heat pump air conditioning system based on variable air volume and variable water volume technologies.Actually,it is very difficult to build test platforms of the seawater-source heat pump ships air-conditioning systems based on VAV and VWV,and the commissioning process is very complex,so it is difficult to carry out experimental research on this system.Therefore,it is necessary for us to use simulation experimental method to replace experimental research.It is different from air-conditioning of land,ships need to navigate in different sea areas,and the external environment temperature and seawater temperature will change frequently,and the load will be more complicated to study.Based on Matlab/Simulink,this paper takes the ship cabin on an ocean-going route as the research object,establishes the cabin model of the ship air-conditioning system based on heat balance,and analyzes the load variation law.The study found that,in the subtropical region,the proportion of fresh air load in the cabin to the total load of the cabin is 46%;in the tropics,the cabin fresh air load accounts for 55% of the total load of the cabin.In different navigation areas,the load changes frequently.The average load of the tropical navigation zone is 2.9 times the average load of the subtropical navigation zone.There is also a significant difference in load at different times in the same navigation zone.The maximum value of the tropical navigation zone load is the minimum value.2.1 times.Firstly,the lumped parameter method was used to establish the model of the seawater source heat pump system,including the compressor,condenser,evaporator and expansion valve.This paper focuses on the parameters that affect the system performance and other components,so the influence of the internal mechanism parameters of the compressor and the heat transfer of the heat exchanger's detailed structure are not considered in the modeling process.Then using the law of conservation of energy to establish a mathematical model of the air conditioner,the three-dimensional flow of the hot and cold fluid is simplified into a one-dimensional steady-state flow for modeling.On the basis of establishing the mathematical model of each equipment of the ship air-conditioning system,it is the first time to combine VAV with VWV model to adapt to changes in cabin load,and a complete ship VAV and VWV air-conditioning system co-simulation platform was established and simulated.The results show that in the subtropical navigation area,the operating parameters of the actual VAV and VWV air-conditioning systems operating for more than 70% of the time are only 40% to 70% of the steady-state algorithm design parameter values;in the tropical zone,the system actually runs 80% of the time.The above operating parameters are 50% to 90% of the steady state algorithm design parameters.In this paper,the wind system adopts the total air volume control method,and the water system uses the backwater temperature control method to adjust the air volume and water volume to adapt to changes in cabin load.As a result,it was found that the energy saving rate of the air-conditioning system with variable air volume and variable water volume is 26.4%.This system is significantly superior to the traditional marine air-conditioning system in economical and energy saving.