Modeling And Simulation Of The Marine Air Condition System

The ship's refrigeration and air conditioning systems is a major ship auxiliary equipment, protection of the normal operation of the device, and can also improve people's living environment, working condition, as well as health situation. Accurately mathematical modeling of marine refrigeration and air conditioning system is very impprtant to the system operation control, simulation and performance analysis, and laboratory construction. The refrigeration system's stable state emulation technique is mature, but screw water chiller refrigeration system dynamic model is developing and imperfect. Moreover, in recent years, lots of domestic and foreign accidents about machine damage and ship damage are caused mostly by the artificial mistakes and errors, this needed to raise the scene consciousness urgently through the methods of actively inquire and evaluate, analysis and monitor to the situation continuously, and take decisive action if necessary.Based on this, the mathematical model of the water chiller is established, by the method of taking the refrigeration and air conditioning system of the wheel "Yu Kun" as the reference object, building the distributed parameter model of the evaporator and condenser, and the concentrated parameter model of the compressor and expansion valve. The summer ventilation system model of cooling and dehumidification is built through establishing heat equations of the cooling water controlled by three-way solenoid valve and the air, and cold load equation of the air-conditioned room, and the winter ventilation system model of warming and humidification is built through establishing heat equations of the steam controlled by three-way solenoid valve and the air, and heat load equation of the air-conditioned room, according to thermodynamics and heat transfer theory. At last, the matrix equation of the ship's refrigeration and the air-conditioning system general model is established by associating equations.The derivation process is simplified by supposing the enthalpy of refrigerant at condenser's import an unknown variable, converting the derivation of the density to the derivation about the variable hci and the condensing temperature, which avoiding to derivate about several variables, and the equation is reduced, lined and optimized, derivation process of state coefficient is simplified through the method that calculating matrix coefficients using relationships among refrigerant temperature, pressure, specific volume and enthalpy, and replacing the original function equation with multi-variable function's Taylor power series expansion equation. Then simulation and calculation is carried on, and compared analysis is took with the ship's test data basing on Matlab a simulation tool, which verifying that the accuracy and real-time simulation has greatly improved.The PLC Procedure and operating flow is analyzed, which including starting control about 3 chiller units,6 compressors,3 chilled water pumps,6 electronic expansion valves, Interlocking control about fans, cooling water pump and compressor, alarm about compressor low oil pressure, cooling water high temperature, cooling water low pressure, programming control about ventilating model, cooling model and heating model of the air conditioner. Based on VS.net, and taking the above logical relations and conditions as the basis, the marine refrigeration and air conditioning simulator simulation software is researched and developed, by establishing Runge-Kutta differential solution algorithm, calling the air-conditioning system's mathematical mode, and developing module. The software is fully functional, system equipment can be operated manually and automatically, cooling water three-way valve or warming steam three-way valve is controlled according to the deviation between the air-conditioned room temperature and the setting value, humidifying steam valve is controlled according to the deviation between the air-conditioned room humidity and the setting value, the PID parameter of cooling water three-way electromagnetic valve, warming solenoid valve and humidifying solenoid valve can be adjusted automatically and manually, the fault and variable can be set and changed, and the pressure, temperature and other parameters can changed really according to the simulated failure; Furthermore, the simulator's interface is friendly, the temperature and humidity of the ventilation system's fresh air, return air and supply air which calculated from background model, and the evaporation pressure, condensing pressure and other important parameters of the water chillers can be displayed.Based on three-dimensional simulation tool 3ds Max and Virtools, the three-dimensional model of the compressor, the heat exchanger, the fan, other equipment and the pipe is built, and real time roaming of three-dimensional scene about air conditioner cabin and chiller compartment is implemented.Through the sockets of C language, communication and interaction between the three-dimensional scene and two-dimensional simulation is achieved, air conditioning equipment can be operated simultaneously in the two-dimensional and three-dimensional scene, and the running situation of device, switch station of the button, knob, and lights can be displayed consistently.Finally, the cooling capacity of the summer's cooling load and the heat capacity of the winter's thermal load conditions in the room is calculated, according to a university refrigeration and air-conditioning laboratory building structure's characteristics, and according to the thermodynamics and heat transfer theory. And so, the compressor type, cooling water tank volume, cooling water pump displacement and the heater power which matching the condition is chosen, the logic control program including protection and alarm function is designed and compiled, the laboratory of the ship refrigeration and air conditioning system is constructed.