The Experts below are selected from a list of 69 Experts worldwide ranked by ideXlab platform

Prodromos Daoutidis - One of the best experts on this subject based on the ideXlab platform.

  • ACC - Modeling and control of a water gas shift membrane reactor for hydrogen production
    2012 American Control Conference (ACC), 2012
    Co-Authors: Dimitrios Georgis, Fernando V. Lima, Ali Almansoori, Prodromos Daoutidis
    Abstract:

    Hydrogen is considered as an alternative to fossil fuels for energy production due to its high energy density and zero carbon emissions. It is typically produced from hydrocarbons via steam reforming or the water gas shift (WGS) reaction. In this paper, we develop a distributed model for a WGS membrane reactor which achieves higher carbon monoxide conversions than these achieved by conventional packed bed reactors. A steady-state analysis under different flow configurations reveals the presence of large temperature gradients (hot spots) in the reactor. Open-loop simulations demonstrate the necessity for a control strategy to suppress the hot spot and maintain the operation of the reactor under a specified temperature reflecting a catalyst Operating Limitation. Three different control strategies are proposed and a case study illustrates and evaluates their performance. A comparative study between a nonlinear and a PI controller is also performed.

Satoshi Tadokoro - One of the best experts on this subject based on the ideXlab platform.

Jian Ling - One of the best experts on this subject based on the ideXlab platform.

  • Critical working frequency of reciprocating heat-transfer devices in axially reciprocating mechanisms
    International Journal of Heat and Mass Transfer, 1998
    Co-Authors: Jian Ling, Yiding Cao, Qian Wang
    Abstract:

    Abstract The reciprocating heat-transfer device or reciprocating heat pipe has a high effective thermal conductance, and applications can be found in various reciprocating mechanisms, including offset cam mechanisms, Scotch yoke mechanisms, and piston assemblies of internal combustion engines. The liquid return mechanism presents the most important Operating Limitation for this type of heat-transfer device. In this paper, the potential applications of the reciprocating heat-transfer device to various reciprocating mechanisms are described. Theoretical analyses are performed for the critical working frequency of the device in connection with the reciprocating mechanisms. An analytical solution and semi-empirical correlation, with and without taking into account the flow resistance, are obtained. Extensive experiments for the critical working frequency are then undertaken on an engine tester. Comparison of the analytical and experimental results indicates that the analytical solutions and semi-empirical correlation provide an accurate prediction for the working limits of reciprocating heat-transfer devices.

  • Operating Limitation of reciprocating heat pipes for piston cooling applications
    1995
    Co-Authors: Yiding Cao, Qian Wang, Jian Ling
    Abstract:

    The technological background of the reciprocating heat pipe (or shaking-up heat pipe) is described. Four reciprocating heat pipes with different geometrical dimensions are tested for the determination of the minimum reciprocal frequency of the heat pipe. The experimental results show that the minimum frequency is lower for a reciprocating heat pipe with a shorter length and larger diameter. Overall, the minimum frequency is essentially insensitive to the variation of heat pipe dimensions and power inputs. This means that the reciprocating heat pipe can be used for piston cooling without encountering any major working Limitations. The experimental results also show that at a higher engine cranking speed, the effective thermal conductance of the reciprocating heat pipe is more than 130 times that of a copper bar having the same size as the heat pipe. This would rank the reciprocating heat as one of the best performers in various heat pipe applications, considering the small length of the reciprocating heat pipe. Finally, a reciprocating heat pipe without air evacuation is tested, which indicates that the contribution of the liquid impingement in the heat pipe is significant, and that this heat pipe works relatively well at a lower heat input. This study ismore » relevant for diesel engines.« less

Dimitrios Georgis - One of the best experts on this subject based on the ideXlab platform.

  • ACC - Modeling and control of a water gas shift membrane reactor for hydrogen production
    2012 American Control Conference (ACC), 2012
    Co-Authors: Dimitrios Georgis, Fernando V. Lima, Ali Almansoori, Prodromos Daoutidis
    Abstract:

    Hydrogen is considered as an alternative to fossil fuels for energy production due to its high energy density and zero carbon emissions. It is typically produced from hydrocarbons via steam reforming or the water gas shift (WGS) reaction. In this paper, we develop a distributed model for a WGS membrane reactor which achieves higher carbon monoxide conversions than these achieved by conventional packed bed reactors. A steady-state analysis under different flow configurations reveals the presence of large temperature gradients (hot spots) in the reactor. Open-loop simulations demonstrate the necessity for a control strategy to suppress the hot spot and maintain the operation of the reactor under a specified temperature reflecting a catalyst Operating Limitation. Three different control strategies are proposed and a case study illustrates and evaluates their performance. A comparative study between a nonlinear and a PI controller is also performed.

G. S. Diniz - One of the best experts on this subject based on the ideXlab platform.

  • Topological nature of in‐gap bound states in disordered large‐gap monolayer transition metal dichalcogenides
    physica status solidi (RRL) - Rapid Research Letters, 2016
    Co-Authors: L. Villegas-lelovsky, G. S. Diniz
    Abstract:

    We propose a physical model based on disordered (a hole punched inside a material) monolayer transition metal dichalcogenides (TMDs) to demonstrate a large-gap quantum valley Hall insulator. We find an emergence of bound states lying inside the bulk gap of the TMDs. They are strongly affected by spin–valley coupling, rest- and kinetic-mass terms and the hole size. In addition, in the whole range of the hole size, at least two in-gap bound states with opposite angular momentum, circulating around the edge of the hole, exist.Their topological insulator (TI) feature is analyzed by the Chern number, characterized by spacial distribution of their probabilities and confirmed by energy dispersion curves (energy vs. angular momentum). It not only sheds light on overcoming low-temperature Operating Limitation of existing narrow-gap TIs, but also opens an opportunity to realize valley- and spin-qubits. (© 2016 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim)