Pressure values at the pump outlet and inlet
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This post was last edited by Black gold on 2011-8-26 06:33. In the case of a closed-loop system, the pressure before it starts operating is known, as are the characteristic curves of the pumps within the system and those of the pipes. So, after it is operated, how should the pressure values at the pump’s outlet and inlet be determined?
The inlet pressure of the pump should be equal to the original system pressure plus the pump’s head. As for how the inlet pressure changes? It is necessary to check the condition of the pipes
The conditions are not complete; the pressure value is indeed a matter of design consideration. After it’s built, just check the pressure gauge and that’s fine
In a closed-loop system, the medium circulation is governed by the operating pressure specified in the system design; this value corresponds to the pump’s outlet pressure. The pump’s inlet pressure is equal to the design pressure minus the pump’s head, which represents the pressure of the system at rest.
In short, the answers from several marine engineers are that the inlet of the pump still has the original static pressure, while the outlet of the pump has the actual head plus the original static pressure, which is essentially the design pressure of the pipeline. So here’s a question: pressure and density are related to each other. The increased pressure results in a density that is higher than the original density. Since the volume of the pipeline remains constant, where does the extra water come from? . . . . Another question: based on the continuity of fluids, as well as the relationship between pressure and density, in areas where the pressure is high, the density is also high, which means the volumetric flow rate is low; therefore, the flow velocity should be low as well. So how can the flow velocity increase gradually along the pipeline? Can it be understood as the conversion of excess pressure energy? In other words, the pressure energy supplied by the pump initially should include the energy lost due to frictional losses along the flow path, as well as an additional amount for kinetic energy?
Upstairs: The outlet pipes of the pumps are designed to be thinner than the inlet pipes, taking into account the issue you mentioned.
The pump outlet pressure increases, the flow rate remains unchanged, the density increases, and the volume decreases
The flow rate has increased, and of course the pressure has increased as well
What are the flow rate and head? The pressure value at the outlet can then be calculated
:) Hehe, it seems that it’s impossible to explain things without numbers. To put it this way, the pipeline is horizontal; the flow rate at the intersection of the pipeline’s characteristic curve and the pump’s characteristic curve is 30 cubic meters per hour, with a pressure of 0.6 MPa. The inlet and outlet of the pump have the same diameter as those of the pipeline, and when the system is not in operation, the static pressure at the inlet and outlet is 1.0 MPa. So, after it is operated, what are the pressures at the inlet and outlet of the pump? Optional answers: A: 1.0, 1.6; B: 0.7, 1.3; C: 0.4, 1.0 ； Or add other answers on your own. . . . . . An additional question: what would be the result if the highest point of the pipeline is 20 meters high, the pump is installed at the lowest point, and all other conditions remain unchanged? Everyone is welcome to discuss. :)