Putting it all together: Energy efficiency opportunities at system levels

31.10.2016

Tero Ahonen, LUT EFEU WP coordinator: Integrated energy efficient systems

Motivation to systems-level research work

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Component efficiency η

•  Fluid handling systems are notable contributor in global energy consumption

•  Energy saving potential decreases gradually with increasing component efficiency, but huge savings still available through:

•  Optimized variable-speed operation of fluid handling systems •  Improved system design, dimensioning and integration

Improvement potential in electric motors •  Modern electric motors provide easily ~90 % efficiency (IE3 class) •  Improvements and simultaneous cost savings possible through:

•  Using of synchronous reluctance rotor; ~2 % units higher efficiency with principally the same motor construction (IE4 eff. class)

•  Motor design so that it is integrated to the flow device; less bearings, possibility to fluid cooling→use of smaller motor size

Savings through optimized system selection •  Existing fluid handling systems are often overdimensioned for the

given application •  Pumping System Optimization Tool has been used to demonstrate

the savings potential available in a paper mill pumping system •  Installation of smaller&more efficient pump and motor •  Analysis of the resulting costs for the time period of 10 years has

shown in 20 % energy savings and payback time of ~3 years

Optimized variable-speed operation •  VSDs allows task execution with minimized energy consumption

•  Optimum rotational speed is affected by the surrounding system, which should be followed during the reservoir filling

•  31% savings in energy consumption, when constant speed of 1300 rpm is replaced with the optimized rotational speed profile

•  Already finding the best constant speed provides ~30% savings

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Potential in optimized fluid device design •  Bale pulpers are used in paper mills to mix fiber pales with water

•  Challenging to design, as the behavior of water-fiber fluids is not yet well characterized

•  Is it possible to redesign existing pulper rotor to reduce process energy consumption even by 30%?

•  New rotor design has decreased power consumption and especially halved the mixing time, leading to ~50% energy savings

•  EFEU program has resulted in •  ~2..4 % improvement in pump impeller and motor efficiency for

fluid handling systems, and with more to come through the benefits of device integration

•  Software tools to determine savings potential of 20 % by optimized system dimensioning

•  Speed control methods resulting e.g. 30 % energy savings against the use of fixed-speed devices

•  Flow device designs with halved energy consumption against existing devices

Summary