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:
Selection process retrofitting to existing equipment:Retrofitting a motor mounted VFD
Compressed Air Transmission and Treatment:COMPRESSED AIR FILTRATION
ACTUATORS:PNEUMATIC-MECHANICAL SYSTEMS
BASIC PRINCIPLES:GAS LAWS AND THERMODYNAMICS.
Optimizing and up-rating of existing systems:Optimizing existing systems
Conveying characteristics:The determination of conveying characteristics
Hydraulic accessories:Steel tubing.
Hydraulic motors:Electro-hydraulic stepping motors.
Modular valves and manifolds.
Air Compressors, Air Treatment and Pressure Regulation:service units
PROPERTIES OF PURE SUBSTANCES:SPECIFIC HEATS
THE FIRST LAW OF THERMODYNAMICS:THE FIRST LAW OF THERMODYNAMICS
ENTROPY
HEAT EXCHANGERS:THE OVERALL HEAT TRANSFER COEFFICIENT
FORCED CONVECTION:TURBULENT FLOW IN TUBES