Document Type : Research Paper

Abstract

In a direct injection sprayer (DI), the delay time to change the concentration of chemicals in the spray tip can have a substantial effect on sprayer performance. Delay time is the most important variable in evaluating the performance of a DI system in real time herbicide application. The flow of solution from the injection point to the nozzles was mathematically modeled to quantitatively evaluate the effect of tube volume and carrier flow rate on dynamic specifications, such as delay time. Plug-Flow and Well-Mixed models were used to model solution flow in DI systems. A DI system was designed and built to allow comparison between the mathematical model and tests results. ANOVA (Duncan test) at a 5% confidence level was used to determine the effect of change of the parameters on the delay time. A factorial completely randomized block design and SPSS 15 software were used for statistical analysis of the data. Comparison of the mathematical model with the test results showed that, for time response, the Well-Mixed model had a more appropriate response time than did the Plug-Flow model. The Well-Mixed model is suggested for predicting the dynamic behavior of a DI system. Both models produced stable state values that were slightly different from test results.

Keywords

Al–Gaadi, K. A. 1992. Monitoring the performance of a ground sprayer with and without control system. M.Sc Thesis. Department of Agricultural and Chemical Engineering. Colorado State University. USA.
Anon. 2002. Richtlinien für die Prüfung von Pflanzenschutzmitteln und Pflanzenschutzgeräten: Merkmale für die Prüfung in Gebrauch befindlicher Spritz- und Sprühgeräte für Flächen-und Raumkulturen. Teil VII. Biologische Bundesanstalt für Land- und Forstwirtschaft (BBA). Berlin. Germany.
Giles, D. K. and Comino, J. A. 1990. Droplet size and spray pattern characteristics of an electronic flow controller for spray nozzles. J. Agric. Eng. Res. 47, 249-267.
GopalaPillai, S., Tian, L. and Zheng, J. 1999. Evaluation of a flow control system for site-specific herbicide applications. T. ASAE. 42(4): 863-870.
Koo, Y. M. and Kuhlman, D. K. 1993. A variable flow nozzle with consistent spray performance. T. ASAE. 36(3): 685-690.
Lovich, M. A., Doles, J. and Peterfreund, R. A. 2005. The impact of carrier flow rate and infusion set dead-volume on the dynamics of intravenous drug delivery. Anesth. Analg. 100(4): 1048-1055.
Mohammadzamani, D., Minaei, S., Alimardani, R., Almassi, M. and Shafikhani. H. R. 2009. Generation a digital management map using gps for herbicide application by VRA spraying. J. Agric. Eng. Res. 10(3): 29-44. (in Farsi)
Paice, M. E. R., Miller, P. C. H. and Day, W. 1996. Control requirements for spatially selective herbicide sprayers. Comput. Electron. Agric. 14(2-3): 163-177.
Rockwell, A. D. and Ayers, P. D. 1996. A variable rate, direct nozzle injection field sprayer. Appl. Eng. Agric.  12(5): 531-538.
Stone, M. L., Giles, D. K. and Dieball, K. J. 1999. Distributed network system for control of spray droplet size and application rate for precision chemical application. American Society of Agricultural Engineers (ASAE). Paper No. 99-3112
Tian, L. and Zheng, J. 2000. Dynamic deposition pattern simulation of modulated spraying. T. ASAE. 43(1): 5-11.
 
Zhu, H., Ozkan, H. E., Fox, R. D., Brazee, R. D. and Derksen, R. C. 1998. Mixture uniformity in supply lines and spray patterns of a laboratory injection sprayer. Appl. Eng. Agric. 14(3): 223-230.