Design Strategies for High-Temperature, High-Pressure Optical Cells

摘要

The past several years have seen an increasing effort to apply optical and spectroscopic techniques to a variety of research projects in supercritical fluids. However, many experimental apparatus are plagued with sporadic leaks or cracked windows. Over the past several years, we have developed two optical cell designs: one for flow reactors, and the other for larger batch reactors. The flow system design uses spring washers to balance the unequal thermal expansions of the reactor and the window materials. This design has been used for 2.0-cm windows with f/3 light-collection mounted in a 0.48-cm- ID flow reactor. A typical design calculation is presented showing the relationship between system pressure, operating pressure, operating temperature, and torque applied to the window-retaining nut. The second design employs an older strategy more appropriate for larger windows. This design uses two seals: one for the window that benefits from the pressure, and a second one that relies on knife-edge, metal-to-metal contact. This design is used in a batch reactor in which we have also installed a stirring mechanism.