Measurement of boundary conditions for numerical solution of temperature fields of metal hydride containers

Abstract

The presented paper describes the measurement of boundary conditions while cooling a metal hydride (MH) container with the La0.85Ce0.15Ni5 alloy. Results are subsequently used for 3D simulation of thermal field in the container during the process of hydrogen absorption. To solve the complicated flow of cooling medium among individual pressure receptacles, ANSYS CFX simulation tool is used and the finite volume method is applied. The same simulation tool is used to describe heat conduction in the metal alloy and the container. For the given construction of the container, uniform distribution of stored hydrogen can be expected among individual receptacles. For cooling the system, cooling radiator is used which is based on Peltier elements. The radiator also enables, in case of desorption, to warm the container. By measuring flows of working substances and the relevant temperatures, it is possible to obtain, by subsequent analysis of temperature flows, the resulting value of the internal heat source. This internal heat source creates a temperature gradient in the container, which impedes exact determination of Pressure Concentration Isotherm curves that should be ideally measured at constant temperature. In addition, measuring in combination with numerical calculations offers a closer look at the absorption process directly in the hydrogen manufacturing plant where, using the alternative energy source, hydrogen is produced and subsequently stored. The results enable to optimize the cooling process in MH hydrogen storage equipment of similar construction and indicate problems with meeting the requirements of the American Department of Energy (DOE).