NiMn mixed oxides with enhanced low-temperature deNOx performance: Insight into the coordinated decoration of MnOx by NiO phase via glycine combustion method

Article abstract of DOI:10.1016/j.apcata.2020.117918

Herein, a facile glycine combustion method was utilized to prepare a series of Ni and Mn based single/double metal oxides, which were evaluated as catalysts for low temperature selective catalytic reduction of NO with NH₃. The NiMn-T samples presented superior catalytic performance especially for NiMn-400, with ～100 % NO_x conversion, >85 % N₂ selectivity within 90-300 °C, and better SO₂ resistance. The superior catalytic activity might be related to the coordination of Ni and Mn, which afforded higher Mn⁴⁺/Mnⁿ⁺ ratio, larger S_BET, more suitable acid site amounts and redox capacity. The improved SO₂ resistance of NiMn-400 catalyst can be ascribed to the less ammonium (bi)sulfate deposition and metal sulfation. In-situ DRIFTS revealed that the Ni doping could deliver more reactive species (NH₂, monodentate nitrite, bidentate nitrate), and the surface acidity is less affected by SO₂, which can account for the enhanced low temperature activity and SO₂ resistance of the NiMn-400 catalyst.

Full text of DOI:10.1016/j.apcata.2020.117918

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Energy Procedia 61 (2014) 2818 – 2821
The 6th International Conference on Applied Energy – ICAE2014
Modeling and identification of circular cylinder-based
piezoaeroelastic energy harvesters
Huliang Daia, Abdessattar Abdelkefib, Qiao Nia, Lin Wanga,*
aHuazhong University of Science and Technology, Wuhan 430074, China
bVirginia Tech, Blacksburg, VA 24061, USA
Abstract
In this paper, we develop a validated nonlinear distributed-parameter model for harvesting energy from vortex-
induced vibrations. The harvester consists of a piezoelectric cantilever beam with a circular cylinder attached to its
end. By using the Euler-Lagrange principle and implementing the Galerkin discretization, a reduced-order model is
derived. Based on a five-mode approximation in the Galerkin approach, an identification for the van der Pol wake
oscillator coefficients is performed. Further analysis is performed to investigate the effects of the cylinder’s tip mass
and electrical load resistance on the synchronization region and performance of the harvester. The results show that,
depending on the operating freestream velocity, the cylinder’s tip mass can be optimized to design enhanced
piezoaeroelastic energy harvesters from vortex-induced vibrations.
© 2014 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
© 2014 The Authors. Published by Elsevier Ltd.
(http://creativecommons.org/licenses/by-nc-nd/3.0/).
Selection and/or peer-review under responsibility of ICAE
Peer-review under responsibility of the Organizing Committee of ICAE2014
Keywords: Energy harvester, vortex-inducedvibrations, experimental identification,Galerkinapproach;
1. Introduction
Converting ambient and aeroelastic vibrations to usable form of electrical energy has been the subject
of several studies over the past few years [1-3]. Many researchers have proposed approaches to convert
wasted mechanical vibrations to electrical energy by using the piezoelectric effect as the transduction
method. One of the most commonly concepts is harvesting energy from flow-induced vibrations [4-6].
Vo rte x-induced vibrations (VIVs) of circular cylinders, however, as one of the common phenomena of
flow-induced vibrations, has been considered by several researchers in order to convert aeroelastic
vibrations to usable form of electrical energy in the past few years [7,8]. A recent experimental research
of a self-excited piezoelectric energy harvester subjected to a uniform flow was done by Akaydin et al. [8].
* Corresponding author. Tel.: +8615827273750;
E-mail address:wanglindds@mail.hust.edu.cn.
1876-6102 © 2014 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/3.0/).
Peer-review under responsibility of the Organizing Committee of ICAE2014
doi:10.1016/j.egypro.2014.12.297

Huliang Dai et al. / Energy Procedia 61 (2014) 2818 – 2821
2819
They tested their designed harvester in a wind tunnel. In their work, however, only experimental results
were performed to evaluate the performance of the harvester.
In this work, our objective is mainly to derive a nonlinear distributed-parameter model for piezoelectric
energy harvesters from vortex-induced vibrations of circular cylinders, as shown in Section 2. A
comparison between the obtained numerical results and the experimental measurements is performed in
Section 3. In Section 4, further analysis is performed to investigate the effect of cylinder’s tip mass on the
performance of circular cylinder-based piezoaeroelastic energy harvester. Summary and conclusions are
presented in Section 5.
2. Modeling and representation of the energy harvester
The energy harvester, under consideration, is composed of a bimorph piezoelectric cantilever beam
with a circular cylinder attached to its free end, as shown in Fig. 1. The piezoelectric sheets are placed on
both sides of the beam, as seen in the red wireframe. The piezoelectric sheets are bounded by two in-
plane electrodes of negligible thickness connected in series to an electrical load resistance, R.
D
y
Lp
o
m0
x
x1
z
( )
w t
Lb
U0
Fig. 1. Schematic of the circular cylinder based-piezoaeroelastic energy harvester.
In this study, we develop a reduced–order model of the piezoaeroelastic energy harvester by applying
the Galerkin procedure to the Lagrangian and virtual work. The final governing equations are given by
n
§
·
ª
«
¬
º
»
¼
CDU0DU0L0
ꢂZ 2r ꢃT V D q
c
c
r ꢂ 29 Z r ꢂ
ªM L ꢂ D 2M L º
M L ꢂ D 2M L
j ꢀ b ꢁ j ꢀ ꢁ
r
ꢁ
i ꢀ b ꢁ
i ꢀ b ꢁ
¨
¨
ꢀ
¸
¸
¦
i
i
i
i
b
j
i
i
i
i
¬
¼
2
j 1
©
¹
(1)
(2)
n
V
R
CpV ꢂ
ꢂ
T r 0
¦
i
i
i 1
n
A
§
D
·
ª
¬
º
q ꢂ OZ q2 ꢃ1 q ꢂZ2q
s ꢀ
M L ꢂ M L
r
i
c
i ꢀ b ꢁ
i ꢀ b ꢁ
ꢁ
¦
s
¨
©
¸
¹
«
»
¼
(3)
D
2
i 1
where q(t) describes the behavior of the near wake and stands for the lift acting on the cylinder; ri(t) are
the modal coordinates of the displacement and φi(x) are the mode shapes of a cantilever beam with a tip
mass; ρ0 is the density of fluid; CL0 and CD are the steady lift and mean sectional drag coefficients which
can be, respectively, considered equal to 0.3 and 1.2 in the region of well-developed wakes [9]; the values
of λ and A are constants and are identified fromthe experimental measurements; ωs is the vortex-shedding
frequency. Some of the other physicalparameters have been given in Table 1.

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Huliang Dai et al. / Energy Procedia 61 (2014) 2818 – 2821
Table 1. Physical and geometric properties of the harvester
Physical properties
PZT elements
Beam
Cylinder
Length, Lp, Lb, L0 (mm)
Width, wp, wb (mm)
31.5
25.4
0.267
ü
267
32.5
0.635
ü
203
ü
Thickness, tp, tb (mm)
ü
Diameter,D (mm)
19.8
Dentisy, ρp, ρb (kg/m3)
Mass, mp, mb, m0 (g)
7800
1.68
66
2730
16
16
ü
ü
ü
ü
Young’s modulus, Ep, Eb (GPa)
70
-1
Strain coefficient,d31 (pmV )
Permittivityat constant strain, ε33 (nFm-1)
-190
13.28
20.3
ü
ü
Capacotance,Cp (nF)
ü
3. Model validation
To determine the accuracy of the developed reduced-order model for piezoelectric energy harvesting
form VIVs, we validate our numerical predictions which are based on five modes in the Galerkin
approach with the experimental measurements of Akaydin et al. [8]. The coefficients λ and A are
identified to be equal to 0.24 and 12, respectively. These values are in good agreement with the suggested
values in [9]. In addition, the physical and geometric properties of this harvesterare presented in Table 1.
0.12
0.3
0.25
0.2
m
m
m
m
m
0=10g
0=15g
0=20g
0=25g
0=30g
Simulation
Experiment
Akaydin et al.(2012)
0.1
0.08
0.06
0.04
0.02
0
0.15
0.1
0.05
0
0.5
1
1.2
1.5
2
0.6
0.8
1
1.2
1.4
1.6
1.8
2
2.2
U0 m s
ꢀ
ꢁ
U0 m s
ꢀ
ꢁ
(a)
(b)
Fig. 2. (a) Comparisons of thevariations of theaverage harvestedpower as a function of the freestream velocity when using the
derived model (solidline) andtheexperimental measurements of Akaydinet al. [14](circles); (b) Variationofthe average harvested
power as a function of the freestream velocity for different tip masses of the cylinder
In Fig. 2 (a), we plot the variation of the average harvested power as a function of the freestream
velocity as obtained from our derived model when considering five modes in the Galerkin discretization
and the experimental measurements of [8]. It is noted that there is an underestimation in the average
harvested power when considering the present model for freestream velocities larger than 1. 5 m/s (post
synchronization region). The presence of a sudden drop in the simulated results is probably due to the
accuracy of the wake oscillator model to the starting of the synchronization region and its peak.
4. Effect of the cylinder’s tip mass on the performance of the energy harvester

Huliang Dai et al. / Energy Procedia 61 (2014) 2818 – 2821
2821
Piezoaeroelastic energy harvesters are designed to be deployed in different locations, such as
ventilation outlets, structure’s surface, rivers, bridges, etc. To this end, Fig. 2 (b ) shows the variation of
the average harvested power as a function of the freestream velocity for different tip masses of the
cylinder. Indeed, the resonant freestream velocity is decreased from about 1.4 m/s to about 0.8 m/s when
the cylinder’s tip mass is increased from 10 g to 30 g. These curves are plotted for the same electrical load
resistance which is 2.46×106 Ω. At this load resistance, we note that a decrease in the cylinder’s tip mass
is accompanied by a wider synchronization region and higher values of the average harvested power.
5. Conclusions
We have derived a nonlinear distributed-parameter model for harvesting energy from vortex-induced
vibrations of a piezoelectric cantilever beam with a circular cylinder attached to its end. Based on the
Eu ler-Lagrange equation and Galerkin discretization, it is demonstrated that there is an excellent
agreement between our derived model and experimental measurements. A parametric study was
performed to investigate the effects of varying the cylinder’s tip mass on the synchronization region, the
performance of the harvester. The results show that a decrease in the cylinder’s tip mass is accompanied
by a wider synchronization region and higher values of the average harvested power.
Acknowledgements
The authors gratefully acknowledge the support provided by the Program for New Century Excellent
Talents in Un iversity (NCET-11-0183) and the Fundamental Research Funds for the Central Universities,
HUST (2013TS034).
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