Experimental Study On Thermal Atomization Characteristic Of Pulsedsmoker/Fogger

The atomization effect of pulsed smoker/fogger plays an important role in the efficient pest control for different growth period of fruit trees. Due to the lack of the theoretical and experimental research on thermal atomization in domestic, a new testing system was designed and the thermal atomization characteristics for diesel and water of pulsed smoker/fogger were studied in this paper.The theoretical model of Helmholtz type pulse-jet engine was analyzed, and the influence law of work frequency affected by the structure paramemters of combustor chamber and exhaust tube, the heating conditions of specific fuel consumption and liquid flux injected into exhaust tube were discussed. Then the relationship between droplet size, work frequency, gas velocity and pesticide properties was established.The working characteristics of pulsed smoker/fogger were measured and analyzed under different working states. The results showed that the work frequency increased as, and its range was 9.7Hz in no-fogging state. In smoker/fog states, the working frequency increased as the specific fuel consumption increased and decreased as the liquid flux increased. Compared with no-fogging state, the average reduction of work frequency in smoke state was 6.6Hz, and was 14.4Hz in fog state. The temperature and gas velocity near the center of exhaust tube exit increased as the specific fuel consumption increased and decreased as the liquid flux increased. Under same throttle opening and liquid flux, both kinetic energy and heat energy of pulsating gas in smoke were higher, and the thermal atomization performance for diesel is better than water.In order to find out the optimum liquid flux and heating conditions for the pulsed smoker/fogger, the atomization effect for diesel and water were studied. The experiment results indicated that the droplet size increased as the diesel flux increased from 20L/h to 90L/h, and all values of D90 were less than 30μm with good atomization effect. The droplet size for water reached the minimum value when the water flux was between 50L/h and 60L/h, and the droplet distribution uniformity was good. The atomization effect for both diesel and water got better as the throttle opening increased. Under the best working conditions that the water flux was between 50L/h and 60L/h and the specific fuel consumption was 1.65kg/h, the volume medium diameter of fog was between 35.85 and 83.71 and could meet the requirement of orchard pest control. The multiple regression model between the droplet size and the main factors was constructed.The matching relationship between the conducting pressure of turbocharged check valve and liquid flux was studied. The experiment results showed that the liquid flux increased as the pressure in pesticide tank increased. Both the maximum pressure and the steady pressure in pesticide tank increased as the throttle opening increased, and decreased as the conducting pressure of turbocharged check valve increased. The best atomization effect and working condition were achieved with the turbocharged check valve with the conducting pressure of 2.81 kPa under the self-pressurization pesticide feeding system of pulsed smoker/fogger. The optimum working time for pulse smoker/fogger in the state of no-fogging was determined, and the waste and pollution of pesticide due to unsuitable liquid flux were avoided.