Automated Research And Design Of Ammonia/carbon Dioxide Cascade Refrigeration System

Refrigerated warehouses are part of the non-staple food project.As the development of economy and the improvement of people’s living standard,the number of refrigerated warehouses in our country is expanding quickly.Although,the whole capacity and the per capita occupation of the refrigerated warehouse has been raised greatly,the designing and producing technique of refrigerated warehouses in our country is still backwarded compared with the advanced techniques.The ratio of automatic refrigerated warehouses with nobody oncall is still low.Such warehouses in our country are only one third the number of those in European countries and America.In order to raise the degree of automation and meet the requirement of energy saving and consumption lowering,this thesis studies the following problems based on the application and development of ammonia/carbon-dioxide cascaded refrigeration system in cold chain industry.Firstly,the thesis designs the hardwares of ammonia/carbon-dioxide cascaded refrigeration system.It explains the composition of the refrigeration system and its application in the field of refrigertion industry.The thesis designs unit control cabinets,skid control cabits,evaporative cooler control cabinets,terminal control cabinets as well as overall controlling PLC cabinets.Besides,it designs the softwares of ammonia/carbon-dioxide cascaded refrigeration system..It explains the operating principle and configuration parameter of this system and designs controlling programs for the refrigeration compressors,evaporation-type condensers,carbon dioxide skids,terminal air coolers and valve sets.The thesis also designs detailed programs for the monitoring systems of the upper computers and proposes various operating reports as well as the curves of system pressure,liquid level and temperature of the warehouses.At last,the thesis analyzes the performance of the system and the result of the operation.It introduces the performance and characteristic of carbon dioxide refrigerant,ammonia refrigerant as well as the freon refrigerant.The thesis lists the testing result of the comparasion between single refrigerant and complex refrigerants.The result shows that after system optimizaion and application of advanced controlling technique,the refrigeration system the thesis studies can maintain the high efficiency of the system and can even realize operation without anyone oncall.The operation of the units and the systems is grasped by internet/LAN.The internet/LAN can manage the operating parameter of the refrigerating process dynamically。It can compare the energy consumed in different period and stablize the refrigeration system.By realizing the high efficiency,stability and energy saving of the refrigeration system,the adoption of such system can bring both economic and environmental benefit to the clients.