The solubility data of carbon dioxide (CO2) in a series
of ionic liquids (ILs): 1-ethyl-3-methylimidazolium tetrafluoroborate
([EMIM]+[BF4]−), 1-butyl-3-methylimidazolium
tetrafluoroborate ([BMIM]+[BF4]−), 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide
([OMIM]+[Tf2N]−), and their
binary mixtures (i.e., [EMIM]+[BF4]− + [OMIM]+[Tf2N]− and [BMIM]+[BF4]− + [OMIM]+[Tf2N]−) at temperatures (313.2 and 333.2) K
and pressures up to 6 MPa were measured by a high-pressure view-cell
technique. The mixed ILs tested were (0, 20, 50, 80, and 100) wt %
[EMIM]+[BF4]− (or [BMIM]+[BF4]−) in [OMIM]+[Tf2N]−. The solubility data of CO2 in pure ILs were correlated with the Peng–Robinson
equation of state (PR EOS), whereas the solubility data of CO2 in mixed ILs can be well predicted based on the mole fraction
average of [EMIM]+[BF4]− (or
[BMIM]+[BF4]−) and [OMIM]+[Tf2N]− over the solubility of
CO2 in pure ILs. It was found that the solubility of CO2 in pure or mixed ILs increases with increasing pressure at
all temperatures but decreases with increasing temperature. The Henry’s
constants follow the order of [BMIM]+[BF4]− + [OMIM]+[Tf2N]− > [EMIM]+[BF4]− + [OMIM]+[Tf2N]− at the same content of
[OMIM]+[Tf2N]−. The use of
mixed ILs provides the opportunity to tune the solubility and selectivity
for capturing CO2 at high pressures. It is the first work
for us to present the solubility data of CO2 in binary
mixtures of ILs at high pressures for physical absorption.
In this paper, we propose a physical model for the analysis of transverse modes in surface acoustic wave (SAW) devices. It is mostly equivalent to the scalar potential (SP) theory, but sufficiently flexible to include various effects such as anisotropy, coupling between multiple modes, etc. First, fundamentals of the proposed model are established and procedures for determining the model parameters are given in detailed. Then the model is implemented in the partial differential equation mode of the commercial finite element analysis software COMSOL. The analysis is carried out for an infinitely long interdigital transducer on the 128°YX-LiNbO3 substrate. As a demonstration, it is shown how the energy leakage changes with the frequency and the device design.
In this paper, we propose the use of the hierarchical cascading technique (HCT) for the finite element method (FEM) analysis of bulk acoustic wave (BAW) devices. First, the implementation of this technique is presented for the FEM analysis of BAW devices. It is shown that the traveling-wave excitation sources proposed by the authors are fully compatible with the HCT. Furthermore, a HCT-based absorbing mechanism is also proposed to replace the perfectly matched layer (PML). Finally, it is demonstrated how the technique is much more efficient in terms of memory consumption and execution time than the full FEM analysis.
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