Abstract. Seed cotton mass flow measurement is necessary for the development of improved gin process control systems that can increase gin efficiency and improve fiber quality. Previous studies led to the development of a seed cotton mass flow rate sensor based on the static pressure drop across the blowbox, which primarily results from acceleration of the seed cotton. The initial sensor did not perform satisfactorily in a gin, and modifications were made to account for air leakage through the rotary valve at the blowbox and the temperature drop occurring due to heat exchange between the seed cotton and air. Mass flow rate was predicted based on the static pressure differences across the blowbox and rotary valve, the air velocity and density at the blowbox inlet, the air density in the blowbox, and the ambient air density. The first- and second-stage seed cotton cleaning and drying systems of the commercial-scale gin at the Cotton Ginning Research Unit were instrumented to test the improved model. Air velocity, cultivar, dryer temperature, and seed cotton feed rate were varied to determine their effects on model accuracy. Mean absolute percentage errors in predicting mass flow rate were 3.89% and 2.85% for the first- and second-stage systems, respectively; however, dryer temperature had a significant effect on the regression coefficients. An additional regression parameter was added to the model to better estimate the average blowbox density, reducing the mean absolute percentage error to 2.5% for both systems and eliminating the effect of dryer temperature on the regression coefficients. Keywords: Cotton, Ginning, Mass flow, Pneumatic conveying, Pressure.
Determination of the uncertainty of mass flow measurement using the orifice for different values of the Reynolds number