THEORETICAL AND EXPERIMENTAL STUDY ON
FLOW CHARACTERISTICS OF A DIAPHRAGM PUMP FOR
UREA-SCR SYSTEMS |
Shu Dong Yang, You Cheng Shi, Xi Wei Pan, Yin Shui Liu |
Huazhong University of Science and Technology |
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ABSTRACT |
Urea selective catalytic reduction (SCR) is the primary technology used to reduce the nitrogen oxides (NOx) of
diesel engine exhaust. To meet the requirements of an SCR system, a novel type of miniature diaphragm pump was designed.
Based on the theory of large deflection of annular plates, the equilibrium equations of a diaphragm with a rigid inclusion were
established, and the equations were solved by the nondimensional method and the finite difference method. Theoretical and
approximated flow model for this pump were proposed. A theoretical relationship between back pressure, rigid inclusion size
and volumetric efficiencies were calculated. To verify the validity of theoretical model, a prototype pump was fabricated and
tested. Experimental results demonstrated that the flow is proportional to the pump speed. The deviation between theoretical,
approximated flow and experimental flow was less than 3.7 % and 9.44 %, respectively. The difference between theoretical
and experimental volumetric efficiency was varied from 3.93 % to 1.49 % when back pressure changed from 0 to 0.9 MPa.
The difference between the two efficiencies of pump with different rigid inclusions varied from 1.49 % to 3.03 % when the
pump operated at rated condition. The pressures in the working chamber showed almost the same overall trends between the
theoretical results and experimental values. The experimental results show that the proposed theoretical model is effective. |
Key Words:
Urea-SCR, Diaphragm pump, Theoretical analysis, Large deflection, Flow characteristics, Volumetric
efficiency, Pressure |
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