Combine simulation model to evaluate design and operation alternatives
Kim, Sang Hun
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A combine is an important but complicated and costly harvesting machine. The development of alternative designs for specific harvesting needs is a difficult, time consuming, and expensive task. A computer simulation model for combine performance was developed, which could provide a solution to better and less costly designs. The objective of this research was to develop a physically based combine simulation model. A model of this type has value in the design of combine machines to meet specific needs such as high grain quality, large machine capacity, low power consumption, and low initial cost. Two prediction models were developed to complete the Texas Tech combine simulation model: (1) prediction of power consumption in a threshing cylinder and (2) a cleaning model to simulate grain and chaff separation on a sieve. The power consumption model was verified with an R^ of 0.901 with published data. A test apparatus was developed to collect grain separation data to verify the derived grain separation equations and to obtain calibrate constants for the derived equations using factorial design and regression analysis. Seven critical variables were included in the cleaning model. The derived grain separation equation fit the measured data with an R^ of 0.995 and was significant at the 99.9 percent probability level. The developed simulation model mathematically describes the threshing, separation, and cleaning processes and predicts the straw to grain ratio, cutting loss, threshing loss, cleaning loss, damaged loss, and power consumption. The results calculated by the complete simulation model were used as input to a robust optimization procedure to optimize the design and operation of a combine harvester. The developed simulation model and optimization procedure should be useful to anyone involved in teaching, research, or design of combine.