Linear pressure loss in solid manure disposal pipes
1992
Asi, M. (Estonian Agricultural Univ., Tartu (Estonia))
To design the manure piston pump pressure loss in pipes, it is necessary to make calculations. For solid manure the use of theoretical models does not give the results with necessary accuracy. The physico-mechanical properties of solid manure vary in a very large scale. To determine the pressure losses the experiments were carried out in cowsheds and a laboratory piston pump was designed. It consists of a mechanical drive, a cylinder and a piston. The velocity of a piston can be varied and the pipes with the diametres 0.125; 0.20; 0.25 and 0.30 m were fitted. The force and pressure acting on the piston and the pressure to the lateral surface of the pipe were recorded by strain measurement technique. Total pressure loss was determined in cowsheds and in laboratory conditions. Moisture content and velocity of manure were changed in a large gap. To get the mathematical model the three-level three-factor orthogonal designs were programmed and carried out. Mean linear loss was considered as the parameter of the experiments. Controllable factors were moisture content of manure (x), pipe diameter (x), and velocity of manure in the pipe (x), the other conditions being equal. As data process the second-degree mathematical models for calculating the pressure loss (5,6) were formed. Uniformity of data dispersion was tested by G-criterion, models validity by F-criterion, and essentiability of regression coefficients by t-criterion
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