Thermal applications in vehicles using Hydralloy C5 in single and coupled metal hydride systems

Abstract Hydralloy C5 (Ti0.95Zr0.05Mn1.46V0.45Fe0.09) is a very fast reacting metal hydride and is therefore investigated for two high thermal power applications in vehicles at room temperature and down to −20 °C: preheating and air conditioning. The experimental findings in a ~1 kg of hydride material scale are evaluated with regard to their implications for potential technical systems. In order to preheat components, Hydralloy C5 can be used to supply hydrogen to LaNi4.85Al0.15, which then releases thermal energy at a high thermal power even from temperatures as low as −20 °C. A main result is that, for the present reactor design, this coupled reaction shows a significant dependency of power on the ambient temperature. In fact, the reaction rate of Hydralloy C5 represents the main limitation on thermal power at low temperature. Nonetheless, the performance of at least 0.5 kW/kgMH allows the preheating of 2 L of lubricant by 20 K within 120 s by 2 kg of metal hydride in 0.8 L of volume. For air conditioning, the endothermal hydrogen desorption performance of Hydralloy C5 was investigated at 10–20 °C. The experiments performed for the considered open system with external hydrogen supply and release show thermal mean powers of up to 2 kW/kgMH. Overall, it is shown that the desorption reaction between 10 and 20 °C is thermally limited in the considered reactor design. Based on the power achieved, less than 4.5 kg of Hydralloy C5 would be sufficient to cover the air conditioning demand in conventional vehicles.