As time goes by, the stored fruits and vegetables will evaporate a certain amount of water, and the control system will automatically humidify according to the humidity detected in the humidity sensor until the set requirements are met. The gas conditioning and preservation is accomplished by a gas regulator (hereinafter referred to as a gas conditioner). In addition, the control system automatically and automatically fills the warehouse with ozone to sterilize the fruits and vegetables.
Control hardware selection and software programming to simplify the system, facilitate maintenance, improve system reliability and on-site resilience, achieve one machine multi-control (that is, one gas control machine controls multiple warehouses), control core hardware for gas conditioning and preservation PLC.PLC has strong I/O control ability and is good at logic analysis and control. After comparison, the system selected S7-200-CPU214), and the expansion module S7-200-EM223 was added.
The system control software can be programmed on the PC with the STEP-7MicroWin32 software provided by SIEMENS, and then the RS232 communication port on the PC is connected to the PLC, and the programmed software is downloaded to the PLC to control the operation of the system.
The characteristics of the PLC control system for gas regulation and preservation are adopted. After the PLC control, the internal connection of the degassing machine is simple and clear, and the operation panel is simple and beautiful. It also has the following characteristics. Two warehouses use one temperature and humidity secondary instrument and one oxygen content secondary instrument, which saves the cost. The system can be started/stopped with only one button (no mechanical self-locking). The realization of one air conditioner simultaneously (or separately) automatically controls the fresh operation of two warehouses. The control process can be flexibly modified according to the different types of fresh-keeping varieties.
The normal operation of the system indicates that the gas-controlled fresh-keeping system controlled by PLC is designed correctly and the operation is stable and reliable. The LD11 aluminum skirt can be fired by isothermal forging process, and can obtain good mechanical properties after CS treatment. The isothermal compression test of the hot extruded rod raw material after CS treatment shows that under the deformation test condition of temperature 480 ° C and strain rate of 0.005 ~ 0.01 / s, the material will exhibit superplastic effect, and its plasticity needs further verification. .
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