Enhancing waste-heat-to-power with moisture measurement Sensors provide essential humidity and dew point measurements to protect components and build trust in hydrogen-based waste-heat-to-power technology
Antti Heikkilä Vaisala JTEC Energy
A novel technology has been developed that converts waste heat into electrical power at higher efficiency and at lower temperatures than many existing waste-heat recovery approaches. JTEC Energy’s process uses hydrogen as the working fluid, pairing a heat-driven compression technology with electrochemical stacks that convert hydrogen pressure into electrical potential. Tight control of moisture is essential to this process. The electrochemical stack needs humidified hydrogen to keep its membranes functioning optimally. Meanwhile, the metal hydride reactors in the waste-heat conversion subsystem must be protected from excessive moisture. To manage that balance, JTEC has developed a closed-loop gas management system that removes and recirculates more than 99.99% of the moisture introduced into the system. For this system to operate reliably, highly accurate moisture measurement is required across conditions ranging from high humidity at the electrochemical stack to the very low dew point levels required before hydrogen can be safely returned to the reactors. These critical measurements also need to be performed with industrial-ready sensors that can operate in hydrogen, support dynamic pressure and flow conditions, integrate with control systems, and meet hazardous area requirements. Protecting a critical system in a demanding hydrogen environment JTEC’s waste-heat-to-power conversion system brings together two subsystems with different moisture requirements: an electrochemical stack
that requires moisture to operate efficiently and metal hydride reactors that must be protected from excess moisture. Waste heat is delivered to one of the metal hydride reactors in the waste-heat conversion subsystem. Metal hydrides act much like a sponge for hydrogen. When cooled, they absorb hydrogen. When heated, they release hydrogen Figure 1 Vaisala DMP dew point probes can be used inline or in a flow through adapter to measure the dew point of process gases in a wide range of moisture, pressure, and temperature ranges. Shown here at JTEC
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