Energy consumption behavior analysis and experimental investigation of a novel technique for energy-efficient operation of submersible pumping system used in Barind Tract of Bangladesh

Abstract

In this present study, energy consumption behavior and performance of the submersible pumping system running at different sites in the Barind Tract of Bangladesh have been investigated and compared with those of the lab test results of new pumps. It is found that the efficiency of the running pumps is 20–40% lower than that of laboratory efficiency. The total operating head of the submersible pump includes a parameter known as “drawdown” which has a significant effect on its performance. The drawdown characteristics of a 15 HP submersible pump have been studied in the laboratory by varying bore well diameter. It is observed that the amount of drawdown, as well as efficiency, decreases significantly with increasing bore well diameter. This work provides new ideas by incorporating three different mechanical devices (plane, bowl, and propeller) attached to the delivery pipe near the pump to achieve higher efficiency as well as lower energy consumption and compared while using no device. It is possible to obtain 55% efficiency by using a bowl type of a mechanical device in an 8-in bore well that is 5% higher while using no device. On the other hand, there is an opportunity to attain 57% efficiency by using all three devices (plane, bowl, and propeller) at a time in 8-in bore well that is 7% higher while using no attachment. By integrating the mechanical devices in the Talaimari pumping site of Rajshahi Water Supply and Sewerage Authority (RWASA), the annual cost and energy savings will be 61,964.52 BDT and 8074.56 kWh, respectively.

Graphical Abstract

Nomenclature table

Formulations/symbols	Description	Ref
${Y}_{1}+\frac{{P}_{1}}{\rho g}+\frac{{V}_{1}^{2}}{2g}+{H}_{p}={Y}_{2}+\frac{{P}_{2}}{\rho g}+\frac{{V}_{2}^{2}}{2g}+{h}_{ls}+{h}_{fm}+{h}_{lb}+n\times {h}_{lf}+{h}_{lo}$	The Bernoulli’s equation is applied between point 1 and point 2 in Fig. 5 where P1, V1, and Y1 are the pressure, velocity, and height, respectively, in point 1. Similarly, P2, V2, and Y2 are the pressure, velocity, and height at point 2. Besides, Hp is the pumping head and ${h}_{ls},$ ${h}_{fm}$, ${h}_{lb}$,${h}_{lf} \mathrm{and} {h}_{lo}$ are various type head loss which are explained in latter	Rajput (2008)
${V}_{1}=\frac{{d}_{2}^{2}}{{d}_{1}^{2}}\times ({V}_{2})$	Applying continuity equation between points 1 and 2. Here, V1 and V2 is the velocity at points 1 and 2 whereas d1 and d2 are the diameter of the well and discharge pipe, respectively
${h}_{ls}=\frac{{V}_{2}^{2}}{2g}\times ({f}_{ls})$	${\mathrm{Where }h}_{ls}$ is the head loss at pump inlet including the effect of the screen (m of water) and ${f}_{ls}$ is the effect of screen factor
${h}_{fm}={f}_{m.}\frac{L}{{d}_{2}}\frac{{V}_{2}^{2}}{2g}$	Where ${h}_{fm}$ is the major head loss due to friction in the discharge pipe (m of water) and ${f}_{m}$ is the friction factor
${h}_{lb}={f}_{lb}\frac{{V}_{2}^{2}}{2g}$	Where ${h}_{lb}$ is the head loss at the bend (m of water) and ${f}_{lb}$ is the factor due to bend
${h}_{lf}={n\times f}_{lf}.\frac{{V}_{2}^{2}}{2g}$	Where n is the no. of flange and ${h}_{lf}$ is the head loss in flange joints (m of water) and ${f}_{lf}$ is the flange factor
${h}_{lo}={f}_{lo}.\frac{{V}_{2}^{2}}{2g}$	Where ${h}_{lo}$ is the head loss at the outlet of discharge pipe (m of water) and ${f}_{lo}$ is the factor at outlet of discharge pipe
Y1 = 0	Y1 = 0, because it is the point at the datum line
$K=\{1-{\left(\frac{{d}_{2}}{{d}_{1}}\right)}^{4}+{f}_{ls}+{f}_{m.}\frac{L}{{d}_{2}}+{f}_{lb}+n{f}_{lf}+{f}_{lo}\}$	Where k is a constant calculated using this equation
${d}_{1}$	Diameter of the well (m)
${d}_{2}$	Diameter of the discharge pipe (m)
$g$	Gravitational acceleration (m/s2)
${H}_{p}$	Pump head gain (m of water)
${\mathrm{H}}_{2}$	Pumping level (m)
${h}_{fm}$	Major head loss due to friction in the discharge pipe (m of water)
${h}_{ls}$	Head loss at pump inlet including the effect of the screen (m of water)
${h}_{lb}$	Head loss at the bend (m of water)
${h}_{lf}$	Head loss in flange joints (m of water)
${h}_{lo}$	Head loss at the outlet of discharge pipe (m of water)
$L$	Length of discharge pipe (m)
$n$	The number of flange joints
$P$	Electricity consumption (watt)
${P}_{1}$	Suction pressure at datum line (m of water)
${P}_{2}$	Delivery pressure in water distribution line (m of water)
$Q$	Discharge (m3/h)
$S$	The specific gravity of water
${V}_{2}$	The velocity of water at the delivery pipe (m/s)
$\rho$	The density of water (kg/m3)
${\eta }_{c}$	Combined efficiency (%)