Experimental Study On Te Mperature Field Distribution Optimization Of Citrus Huanglongbing Rapid Thermal Treatment

As a devastating disease of citrus,seriously endanger China’s citrus industry,and its increasingly serious harm,there is no way to cure.Therefore,to explore effective orange citrus disease prevention and control methods is imminent.In this paper,the hot air treatment and far infrared treatment methods were proposed,and the temperature field distributions of the two methods were studied respectively to determine the better parameters,which la id the foundation for the study of the effect of the two methods.Then,two kinds of treatments were carried out by hot air and far infrared.The effect of the two methods was compared by PCR.Finally,the treatment methods and the corresponding parameters were obtained.For the hot air treatment,the influence of return air duct existence or not,wind speed,hot air inlet position,outlet position,and inlet hot air temperature on the temperature field distribution of hot air treatmentwere studied.The results show that the wind speed,hot air inlet position,outlet position and inlet hot air temperature have significant influence on the temperature field of each section(P<0.05).The return air duct not only can make the temperature field more uniform,and can reduce energy consumption.The optimum parameters for the rapid hot air treatment of citrus Huanglongbingare that there is a return air duct,wind speed is 14.5m/s,hot air inlet position is located at the lower layer of the enclosure,hot air outlet position is located at the upper layer of the enclosure,and has a 90 degree angle with the inlet position,and the inlet hot air temperature is 90℃.Under this preferred parameter,the temperature in the treatment enclosure rises from 32℃ to 48℃takes about 9 min,the temperature range of the whole enclosure is 3.9℃,and drops 14.1℃ compared to it under non-optimal parameter.For the far infrared treatment,the influence of the number of far infrared lamps,thepower of single far infrared lamp,the heating time,the distance between far infrared lamp and the top of the bracket on the temperature field distribution in the treatment enclosure were studied.The results show that the number of far infrared lamps,the power of single far infrared lamp and the heating time have a significant effect on the temperature field distribution of leaves and branches(P<0.05),the distance between the far infrared lamp and the top of the stent has a significant effect on the temperature field distribution of the leaves(P<0.05).The optimum parameters are as follows: the number of far infrared lamps is 3,the power of single far infrared lamp is 1 k W,the heating time is 3 min,and the distance between far infrared light and bracket is 10 cm.Under this condition,the average temperature of leaves was 58.1℃,the average temperature of b ranches was 43.1℃,and the average temperature of the whole was 52.3℃.Using the above parameters for citrus Huanglongbing field treatment test,the concentration of pathogens decreased by 66.2% after hot air treatment,by 38.4% after far infrared treatment.The results show that the treatment effect of hot air treatment was better than that of far infrared treatment.There are some effects on the control of citrus Huanglong disease,and the treatment effect of hot air treatment is better than that of far infrared treatment.