In CDR applications, pumps are used for circulating and transferring water to grow microalgae, to move seawater through electrochemical cells in ocean alkalinization projects, to circulate cooling water in biomass energy conversion plants and deliver quench water in some biochar operations, and to increase the pressure of supercritical carbon dioxide in pipelines.
Pumps convert electrical energy into mechanical energy – imparting energy to give the fluid velocity, raise its elevation, and increase its pressure. The energy increase is expressed in terms of the height of a vertical column of the fluid, called the “total head” of the fluid. Total head is an expression of the pump’s delivered pressure - which might be used to raise elevation or overcome friction. Some electrical energy is lost to heat in the electric motor and friction between parts of the pump, so the percentage that is successfully delivered to the fluid head is the overall efficiency. Many larger commercial centrifugal pumps have efficiency around 70%. Small retail pumps may have efficiency of less than 20%. Although centrifugal pumps are most common, there are several other types: positive-displacement piston pumps, progressing cavity pumps, and peristaltic pumps; air-lift pumps, and ejector pumps.
The fluid flow energy produced by a pump is simply E = mgh, where m is the mass flow rate (kg/s), g is the acceleration due to gravity, 9.81 m/s2, and h is the total head (m). In these units, the product is Newton-m/s, or Watts. The density of water is about 1000 kg/m3 (1024 kg/m3 for seawater).
example: A centrifugal pump with a flow of 20 m3/h, a total head of 10 m, and an efficiency of 65% requires,
E = (20 m3/h) x (1 h/3600 s) x (1000 kg/m3) x (9.81 m/s2) x (10 m) / (65%)
= 838 kg-m2/s3 = 838 watts (1.1 hp)
Additional Information
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