CONTENTs PAGE| 2|
EXPERIMENTAL METHODS| 5|
This study was undertaken to investigate the characteristics of a Centrifugal pump. The Centrifugal pump is largely used in petrochemical industries to move liquids around the plants and refineries.
Through common practise of Centrifugal pump operating characteristics is it possible to determine the optimum conditions of particular conditions. The results of typical characteristics are expressed on this work in terms of pump discharge pressure, pump efficiency, and power demand at various pump speeds of verses pump discharge.
The experimental observation of this lab reports has shown that the higher pressure difference the lower the pump discharge (pump flow rate), the longer time it took water to move the lower the flow rate since the mass of water was at constant 10 kg.
The pump efficiency of this laboratory work is relatively low. This could be due to systematic experimental errors during the lab work. The pressure difference of outlet and inlet pressures has major effect on the characteristics of centrifugal pump.
The objective of this experiment was to investigate energy transfer in a pump, the centrifugal pumps is common choice for pumping liquid of a low medium viscosity, such as water or oil. It is low in cost, and the rate flow can be arrived quite simply, by restricting the flow rate using a valve. Many centrifugal pumps can even run against a closed valve (no flow) for a short time. Electrical energy turns the drive shaft. This rotates the impeller within the pump, pressuring the liquid and forcing it to circulate. In a perfectly efficient system, all the electrical energy, Ee would be converted to shaft energy, Es. This in turn will be converted to fluid energy in the water, Ew. The expressions of these are below. Ee = Vi
When V is volts, i is amperes. Note that although this simple equation applies with the DC motor of this apparatus, other equipment may have a different relation. Es = Lr where L is the shaft load in newtons, r is the torque radius arm length (see Data) and is the rotational speed in radians per second. Note: 1 revolution = 2 radians. 1 rpm = 0.105 rad/s. Ew = Q(p2 – p1), i.e. product of volume flow and pressure rise. In practice some energy is dissipated as heat, so Ee > Es > Ew We express the efficiency of a machine as the ratio of work got out over work put in. Choosing Es as the input, = Ew/Es .
The useful apparatus of this experiment was provided on the plain paper (hand drawn presentation) and it was well labelled and sketched using Hp pence on page 10. The hand draw experimental diagram is done a lab (N3) centrifugal pump that was used to investigate energy transfer in the system (pump) and to study the characteristics of the system. The pump was connected to an electrical power supply. Then data has been recorded for the analyses to identify the characteristics and energy transfer. The recorded measurements were pressure (P1 and P2), volume of the tank, load, time and current. These are the measurement needed for the analyses.
* Set the voltage to give an indicated speed on the dynamometer of 600 rpm. Note that there is a 2:1 pulley gearing, so the pump shaft will turn at 1200 rpm. * Ensure that the valve between pump and tank is fully open, and do not touch this. * Open the discharge valve to its full extent. When the flow is settled, record V, i, L, p1 and p2. * To measure flow, record the time to fill the graduated bucket, using the stop clock provided. * Open the drain immediately the high level is reached, as otherwise the bucket will overflow. * Record the mass m collected. Repeat, adjusting the discharge valve to reduce the...