Fiber-optic fluorescence array to study free convection in porous media

A 64-point fiber-optic fluorescence array is integrated into a heated-packed bed to study free convection in porous media. The array consists of 64 individual fluorescence coupler-detector modules. The array modules are designed for rhodamine 6G dye and allow real-time measurement of tracer concentrations to about 40 ppb. The coupler-detectors are inexpensive and allow a single fiber to carry both the excitation light and the emitted fluorescence light between the detectors and the remote probe terminations at known locations within the bed. Dilute pulses of tracer dye are injected into the packed bed and the dye concentration at each of the 64 fiber-optic probe terminations is monitored as a function of elapsed time. The tracer concentration as a function of time and position allows the fluid movement to be followed within the porous medium