Page 52 - ASME DSCC 2015 Program

Technical Program

natural Gas Hydrogen Reformer Controller Design With Disturbance
ConTRIBuTED SESSIon
1-10-1 TM4 natural Gas and Heat Exchangers Rejection
Geroge Bellows f 1:30pm–3:30pm Contributed regular paper. DSCC2015-9970
Verica Gajic, Patrick Rose, Villanova Univerisity, Villanova, PA, United
Session Chair: Bryan Keating, University of Illinois at Urbana Champaign States
Session Co-Chair: xingyong Song, Halliburton Energy Service Co
In this paper we present a controller design for a linearized model of a fuel
cell hydrogen gas reformer, which produces hydrogen from natural gas. We
Modeling of Ionic Polymer-Metal Composite-Enabled Hydrogen Gas
design two feedback control loops, one of them with an integrator and an-
Production
other one with proportional state feedback. In the third step, a feed-forward
Contributed regular paper. DSCC2015-9922
controller is designed whose role is to off-set for the impact of the distur-
Tushar nagpure, Zheng Chen, Wichita State University, Wichita, KS, United bance represented by the fuel cell current. Both the feedback controller and
States
the feed-forward controller are obtained through a rigorous dynamic opti-
Hydrogen extraction using water electrolysis, and microbial biomass conver- mization process of a quadratic performance criterion along trajectories of
sion are clean and minimum-emission option for renewable energy storage a linear dynamic system. According to the presented simulation results, the
applications. Ionic polymer-metal composite (IPMC) is a category of elec- proposed controller copes well with the disturbance and reduces its impact
tro-active polymers that exhibits the property of ion migration under the ap- within a few seconds from the time when the disturbance occurs, despite
plication of external voltage. This property of IPMC is useful in electrolysis of large jumps in the fuel cell current (disturbance).
water (H2O) and produce hydrogen (H2) and oxygen (O2) gases. This paper
Model Reduction and optimization of natural Gas Pipeline Dynamics
discusses the electrochemical fundamentals of electrolysis, which provides
Contributed regular paper. DSCC2015-9683
a linear relationship between the flow rate of hydrogen from electrolysis and
Anatoly Zlotnik, Scott Backhaus, Michael Chertkov, Los Alamos National
the source current. An IPMC electrolyzer circuit model is developed to cap-
Laboratory, Los Alamos, NM, United States, Sergey Dyachenko, The
ture the electrical characteristic of IPMC. The model incorporates nonlinear
University of Arizona, Tucson, AZ, United States
capacitance, pseudo-capacitance, and a nonlinear resistance defined with a
polynomial function. A state-space equation is then obtained to simulate the We derive a reduced control system model for the dynamics of compress-
proposed circuit model for electrolysis. Experimental result shows that the ible gas flow through a pipeline subject to distributed time-varying injections,
flow-rate of hydrogen production is proportional to the system current and withdrawals, and control actions of compressors. The gas dynamics PDE
the proposed model validates the step-response of the system. The model equations are simplified using lumped elements to a nonlinear ODE system
prediction error is less than 4.5647%. with matrix coefficients. We verify that low-order integration of this ODE
system with adaptive time-stepping is computationally consistent with solu-
Wiener Modeling of a Closed loop Vapor Compression System for
tion of the PDE system using a split-step characteristic scheme on a regular
Extremum Seeking Control Design
space-time grid for a realistic pipeline model. Furthermore, the reduced
Contributed regular paper. DSCC2015-9941
model is tractable for use as the dynamic constraints of the optimal control
Bryan Keating, Justin P. Koeln, Andrew G. Alleyne, University of Illinois at problem of minimizing compression costs given transient withdrawals and
Urbana-Champaign, Urbana, IL, United States gas pressure constraints. We discretize this problem as a finite nonlinear
This paper demonstrates that the dynamic relationship between the power program using a pseudospectral collocation scheme, which we solve to
consumption of a vapor compression system under closed loop control and obtain a polynomial approximation of the optimal transient compression
its evaporator and condenser fan inputs is well described about a nominal controls. The method is applied to an example involving the Williams-
operating point by a Wiener model, which is useful for extremum seeking Transco pipeline.
controller design. Information about the input dynamics from the Wiener
Dynamic Modeling of Heat Exchangers With Humidity and
model is used to evaluate the tradeoff between steady-state error and
Condensation
convergence time for single and dual input extremum seeking controllers in
Contributed regular paper. DSCC2015-9646
simulation.
Herschel Pangborn, Andrew G. Alleyne, University of Illinois at Urbana-
Champaign, Urbana, IL, United States
The effects of air humidity on the performance of refrigerant-to-air heat ex-
changers in vapor compression systems (VCSs) are non-negligible in model-
ing and control design for some applications. Such applications include both
those in which the ambient humidity is expected to vary greatly over time
and those in which control of the air outlet humidity is desired. This paper
presents a control-oriented dynamic model for cross-flow refrigerant-to-air
heat exchangers that uses knowledge of the air inlet humidity to improve the
accuracy of refrigerant-side and air-side outputs, as well as to calculate the
air outlet humidity and rate of condensate formation. Simulation results are
validated with experimental data collected from a 1kW VCS test stand.
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