Daigoro Mori

High-pressure Metal Hydride Tank for Fuel Cell Vehicles

A new type of hydrogen-absorbing alloy tank has been developed. The high-pressure metal hydride (MH) tank has been designed based on a 35 MPa cylinder vessel. The heat exchanger module is integrated into the tank. Its advantage over high-pressure cylinder vessels is its large hydrogen storage capacity, for example 7.3 kg with a tank volume of 180 L. Cruising range is about 2.5 times longer than that of a 35 MPa cylinder vessel system with the same volume. The hydrogen-charging rate of this system is equal to the 35 MPa cylinders without any external cooling facility. Furthermore, release of hydrogen at 243 K is enabled due to the use of a hydrogen-absorbing alloy with a high disassociation pressure, Ti-Cr-Mn alloy with AB2 laves phase. It is thought that the high-pressure MH system is one realistic option for fuel cell vehicles to achieve a cruising range of over 700 km.

Thermal Analysis of High-Pressure Metal Hydride Tank for Automotive Application

A new type of hydrogen storage tank has been developed for fuel cell vehicles FCHV. The tank design is based on the 35MPa high-pressure cylinder vessel and the heat exchanger module including hydrogen absorbing alloy with high dissociation pressure is integrated in it. To hydrogen absorbing alloy, for example, Ti-Cr-Mn alloy with AB2 laves phase is applied. Its effective hydrogen weight capacity is 1.9 wt% and reaction enthalpy is −2 kJ/molH2. To optimize the heat exchanger, thermal analyzing method was developed to predict the amount of hydrogen absorption or desorption. The simulation consists of heat and mass balance. Heat balance is made by the hydrogen absorbing alloy, heat exchanger and coolant each other. Also reaction heat of the hydrogen absorbing alloy and compressed heat are considered. The reaction heat is calculated from the equation of reaction rate that is derived experimentally. Furthermore, an additional simulation to predict the charging performance of on-board high-pressure MH tank system by the radiator cooling will be reported. With this simulation, it will become possible to make parameter studies to investigate how the operating conditions influence the performance of tank system.