STTR Phase I: Active Fiber Optic Sensor Array for Cryogenic Fuel Monitoring and Management

这份小型企业技术转让(STTR)第一阶段提案涉及管理液化天然气和氢燃料供应经济性的关键组成部分。运输和储存低温液体燃料有起火和爆炸的危险。由于这些燃料技术正在发展并获得越来越多的美国战略和全球重要性，因此需要传感器和仪器来安全地管理它。这项工作的成果将是匹兹堡大学首次展示的一项基本技术，该技术由光纤内光供电的有源光纤传感器组成，用于测量低温液体的液位、温度和空气中的氢浓度。这种传感器可以在一根光纤上的多个点上进行多路复用。传感器是光纤布拉格光栅(FBG)，它产生的信号与光强度噪声、电磁干扰无关，并且是全介质的，避免了电火花的可能性。在激光加热关闭的情况下，可以准确测量温度，以检测液体密度分层等管理问题。在加热激光作用下，利用功能镀膜的布拉格光栅可以测量冷态液体和气体之间的热导差，从而实现水平仪的传感。通过在每个布拉格光栅处施加到光纤上的钯膜中的氢的吸收而引起的光纤上的应变来检测氢。钯将被加热的激光加热到最活跃的温度范围，即使它靠近冷管道或容器。如果成功，这项技术将有助于在运输液化天然气时提供安全保障。人员和设施的安全也是非常重要和有影响的。一场严重的事故可能会推迟氢作为主要燃料来源的广泛采用。拥有一个灵活的多用途系统，可以绝对自信地安装，以监测和管理这些燃料以及已安装系统的健康状况，将对接受氢气作为安全的替代燃料来源产生重大影响。在一根光纤上复接多个传感器的能力将使低温壁上的穿透更安全、更经济，而光纤的低腐蚀电位将使传感器能够沿管道放置在地下。同样基本的有源光纤传感器技术有可能扩展到燃油流量和其他经济有用的功能。

This Small Business Technology Transfer (STTR) Phase I proposal addresses key components for managing the liquid natural gas and hydrogen fuel supply economy. Transporting and storing cryogenic liquid fuels entails danger of fire and explosion. Since these fuel technologies are growing and acquiring increasing US strategic as well as worldwide importance, sensors and instrumentation to safely manage it are required. The outcome of this work will be a basic technology, first demonstrated at the University of Pittsburgh, consisting of active fiber optic sensors powered by in-fiber light, to measure cryogenic liquid level, temperature and hydrogen concentration in air. Such sensors can be multiplexed at multiple points on a single fiber. The sensors are fiber Bragg gratings (FBG), which produce a signal that is independent of optical intensity noise, electromagnetic interference, and are all-dielectric, avoiding the potential for electrical sparking. With the heating laser off, temperature can be accurately measured to detect liquid density stratification and other management problems. With the heating laser on, Bragg grating with functional coating can be used to measure the thermal conductance difference between cold liquids and gases for leveling sensing. Hydrogen is detected by the strain on the fiber induced by the absorption of hydrogen in a palladium film applied to the fiber at each Bragg grating. The palladium will be heated by the heating laser into a temperature range where it is most active even if it is near a cold pipe or vessel. If successful this technology will assist in providing security when transporting liquid natural gases. The safety of people and facilities are also great importance and impact. A bad accident could delay the wide adoption of hydrogen as a major fuel source. Having a flexible, multi-use system available that can be installed with absolute confidence to monitor and manage these fuels, as well as the health of installed systems, will have a major impact on the acceptance of hydrogen as a safe alternative fuel source. The ability to multiplex many sensors on a single fiber will enable safer and more economical penetrations in cryogenic walls and the low corrosion potential of the fibers will enable sensors to be placed along piping underground. The same basic active fiber sensor technology has the potential to be extended to fuel flow and other economically useful functions.