Environmental Engineering Reference
In-Depth Information
Experimental results of closed-loop distributed de-icing were also presented on
a stationary turbine blade part at a fixed pitch angle inside a custom icing chamber.
Scaling up the experimental results showed that using combined OFDR with
temperature sensing and distributed PID control uses a total power expenditure of
less than 0.5 % of the rated power under light/medium icing conditions; de-icing
could yield a larger percentage of power improvement and a longer turbine uptime
in cold regions. The power consumption for this localized heating was only about
10 % of the power used when uniformly heating the blade. Furthermore, de-icing
performance of high-intensity pulsed actuation versus continuous low intensity
actuation was investigated. The results show that using high intensity pulse
amplitude modulation (PAM) actuation achieves better de-icing performance than
continuous PID control.
8.12 Future Work
In future work, in order to optimize the heater layout design on a full-scale blade
of a specific wind turbine, we will look at the effect of different ice shapes, sizes,
and locations on lift, drag, and power using a computational fluid mechanics
approach. Optimal layout design of the heaters for active de-icing depends on the
blade size, thermal properties, and the cost of heaters, which can vary from the
results discussed in Sect.
8.9
. In addition, we will use the computational model for
the development of a pseudo-analytical aero/thermodynamic model that can be
used to estimate leading edge temperatures instead of requiring temperature sen-
sors. The temperature estimates can then be used to calculate closed-loop com-
mands for each individual resistor. Furthermore, this model will be very useful in
designing suitable closed-loop control strategies under known faulty resistors in
the network.
Acknowledgments The authors would like to thank Patrick Wagner from the University of
Colorado Boulder for his help in the fabrication of the experimental setup, Dr. Eric D. Moore
from Chiaro Technologies LLC for his help in integrating the closed-loop control module and the
signal processing codes for ice detection into a pre-developed OFDR software module, Dr.
Patrick Moriarty from the U.S. National Renewable Energy Laboratory (NREL) for providing a
blade part for our experiments, Prof. Kurt Maute from the University of Colorado Boulder for
suggesting the ANSYS software for the numerical modeling of ice melting, and Dr. Ali Najafi
from ANSYS Inc. for explaining how to calculate the volume of ice residue in ANSYS. The
authors would also like to thank Fiona Dunne, Eric J. Simley, Jacob Aho, Jason Laks, Andrew
Buckspan, and Hua Zhong for their valuable comments and feedback during the progress of this
research at the University of Colorado Boulder.
