Research On The Control System Of Intelligent Temperature Grain Storage Based On Mixed Refrigerant Method

With the improvement of living standard, people have a higher demand for thesafety, nutrition and taste of food. In the past, people usually reduce the water content ofthe grain to keep it from deteriorating under room temperature, but theycan’t control itsnatural aging, and low moisture will also undermine the quality of grain. In recent years,advanced grain storage theory prove that low temperature storage is an effective way tokeep grain fresh and its process of mildewing and aging. Currently, many families oftenfind their grain deteriorated and even worms because of improper storage. Therefore,the development of household grain storage in which temperature can be controlled hasimportant implications for household food storage.At present, the refrigeration technology of household refrigerator on the home andabroad market mainly three types: compression, diffusion-absorption andsemiconductor. Diffusion-absorption refrigerator mainly heat the concentrated solutionof the generator to achieve refrigeration, and semiconductor refrigerator is needed tokeep a good cooling at the hot end of refrigerant sheet, while the refrigeration power ishigh it even need additional energy to drive cooling fan. The heat loss of the hot end ofrefrigerant sheet and extra energy for driving the fan result in low efficiency, somenoise and the shortening of life. All of that restrict the deve lopment of thesemiconductor refrigeration.In order to improve the effect of the refrigerant system, with combinating thecharacteristics of two refrigerant methods, this article puts forward the optimizationstrategy of the mixed refirgeration, which makes use of the heat loss in the hot side ofthe semiconductor piece as part of the driving force of the diffusion-absorptionrefrigeratnt system, and do some experiments on the grain storage which work based onthe mixed refrigerant method to verify the preheat method. With respect to thediffusion-absorption refrigeration, mixed refrigeration system with preheating methodaccelerates the response speed and improve the efficiency of overall refrigerationsystem.This article use DXP to design the hardware circuit with the processor STM32F103,including the power supply board, control board and drive board, integrated temperatureand humidity acquisition module, ultrasonic level acquisition module, semiconductorrefrigeration H-bridge driver module, the diffusion-absorption refrigeration thyristordrive module and WIFI module. By the two interactive programs LCD touch screen andremote clients, which make grain storage intelligent, the user could monitor the grainstorage conveniently. The topic programs in MDK develop environment, embedded the Real Time multi-tasking Operation System UCOS-II in the STM32F103processor to ensure acquiringtemperature and humidity, level and other data real-time and display that on the LCDtouch screen. With the moving average filter processing, the accuracy of data getsimproved, which providing a basis for the fuzzy control.Client software is written in LABVIEW platform, exchange data with grain storagedevice via WIFI module integrated in the control circuit, The grain stora ge remotemonitoring platform which is compliance with smart home are designed based onnetworking technology. TCP/IP network communication protocol ensures maximumreliability and stability of data transmission.Since mixed refrigerant-based refrigeration system is complex and couldn’t berepresented as a precise mathematical model, the traditional control methods aredifficult to obtain good result. By combining the different characteristics of two kinds ofrefrigeration system, the article puts forward the mixed refrigerant temperature controlstrategy. Relative to off-on control, the fuzzy control strategy of temperature is moreaccurate and stable, and the power consumption can also be significantly reduced.