Systems without static head or closed loop systems
The specific energy here is dependent on the frictional head loss which, in turn, is determined by the losses in the pipe system (including throttling valves), and by the combined drive-motor-pump efficiency.
The combined drive-motor-pump efficiency has to be evaluated for each duty point. It is to be noted that the pump efficiency remains approxi mately the same in a system of this type when the speed is changed, whereas the drive-motor efficiency can drop drastically as the load is reduced. If on the other hand, the system curve is changed by changing the setting of a valve, this will change the duty point of the pump and, hence, its efficiency.
Related posts:
Case studies:Variable speed drives on heating, ventilating, air conditioning {HVAC) system pumps.
Benefits, drawbacks and operational issues:Motordesign
Control principles for variable speed pumping:Methods of controlling a rotodynamic pump
Concepts for estimating pumping energy costs:Specific energy
Compressed Air Transmission and Treatment:Compressed air distribution
Air only relationships:Air flow rate control
Pipelines and valves:Isolating valves and Butterfly valves
THE COMPRESSOR:COMPRESSOR CLASSIFICATION AND SELECTION.
Optimizing and up-rating of existing systems:System not capable of duty
Low pressure and vacuum:Venturi feeders and Commercial venturi feeder
Material property influences:Material grade influences and Alumina.
Control components in a hydraulic system:Sequencing valve.
Air treatment:Stages of air treatment,Filters,Air dryers and Lubricators.
Hydraulic and Pneumatic Accessories:Hydraulic accumulators
ENERGY TRANSFER BY HEAT,WORK,AND MASS:ENERGY TRANSFER BY WORK