Effects of a Bladder Accumulator on Pressure Pulsation of Urea Dosing System

Non-air-assisted urea dosing systems (NAUDSs) with diaphragm pump are usually used in selective catalytic reduction (SCR) systems to supply the urea water solution. The system pressure pulsation caused by diaphragm pump can significantly reduce the injecting precision of NAUDSs and further decrease the conversion efficiency of the SCR systems. Therefore, this study aimed to reduce the system pressure pulsation by installing a bladder accumulator in a NAUDS. The bladder accumulator could effectively absorb the system pressure pulsation. A numerical model was proposed to study the effects of the bladder accumulator on the pressure pulsation of the NAUDS. The software Amesim 15.0
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and ADINA 9.3
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were used to develop a new submodel for the bladder accumulator and the diaphragm pump in the NAUDS. Simulation results show that the pressure pulsation of the NAUDS mainly depended on the bladder accumulator parameter. Reducing bladder thickness, bladder elasticity modulus, and bladder accumulator stiffness significantly decreased the system pressure pulsation. When the stiffness of the bladder accumulator was lower than $5\times 10^{11}$ Pa/m
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, the pulsation ratio of system pressure reduced to below 5%. A test system was built to validate the numerical model. The test data of the system pressure showed almost the same change trend as the simulation results. Thus, the proposed numerical model can effectively predict the dynamic behavior of the NAUDS, and the results may serve as a reference for the design of similar NAUDSs.