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Metal hydride pump (MHP) is one of the unconventional pumping systems which converts thermal energy into mechanical energy. This pump operates in an autonomous mode without the consumption of electric power. So, it is used to solve problems of availability of electricity or fossil energies in certain freestanding regions.

Metal hydride water pumping system uses hydrogen as working fluid to pump water for low head and high discharge. The principal operation of this pump is based on the desorption of hydrogen at high pressure and its absorption at low pressure by a metal hydride. This work is devoted to study a concept of the dynamic behavior of a metal hydride pump using unsteady model and LaNi5 as hydriding alloy. This study shows that with MHP, it is possible to pump 340l/kg-cycle of water in 15 000s using 1 Kg of LaNi5 at a desorption temperature of 360 K, a pumping head equal to 5 m and a desorption gear ratio equal to 33. This study reveals also that the error given by the steady model, using LaNi5 is about 2%.A dimensional mathematical model and the governing equations of the pump were presented to predict the coupled heat and mass transfer within the MHP. Then, a numerical simulation is carried out to present the time evolution of the specific water discharge and to test the effect of different parameters (desorption temperature, absorption temperature, desorption gear ratio) on the performance of the water pumping system (specific water discharge, pumping efficiency and pumping time). In addition, a comparison between results obtained with steady and unsteady model is performed with different hydride mass. Finally, a geometric configuration of the reactor is simulated to optimize the pumping time., {"references":["Solovey AI. Frovol VP. Metal hydride heat pump for waterning system. Int J Hydrogen Energy 2001 ;26 (7) :707.","Rajendra Prasad UA, Maiya MP, Srinivasa Murthy S. Performance of a heat operated metal hydride water pumping system. In: VII world renewable energy congress, Cologne, Germany, 29 Junee5 July; 2002","Miled, A., Askri F., Ben Nasrallah S. Numerical study of the dynamic behavior of a metal hydride pump. (2015) International Journal of Hydrogen Energy, 40 (2), pp. 1083-1095","Rajendra Prasad,M. Prakash Maiya, S. Srinivasa Murthy, Parametric studies on a heat operated metal hydride based water pumping system, International Journal of Hydrogen Energy 28 (2003) 429 – 436","Rajendra Prasad,M. PrakashMaiya, S. Srinivasa Murthy∗, Metal hydride water pumping system for low head-high discharge applications, International Journal of Hydrogen Energy 29 (2004) 501 – 508.","Jemni A, Ben nasrallah S. Study of two-dimensional heat and mass transfer during desorption in a metal hydrogen reactor. Int J Hydrogen Energy 1995;20(1):43e52.","Nishizaki T, MiyAmoto K, Yoshida K. Coefficients of performance of hydride heat pumps. J Less-common. Met 1983,89;559.","Huston E.L. Sandrock GD. Engineering properties of metal hydride. J Less- Common Met 1980 ;74 :435","Groll M, Klem H-P, Metal hydride technology with special emphasis on thermodynamic machine, Fifth ISHMT-ASME heat & Mass Transfer conference, Calcutta, India, 3-5 January 2002\n[10]\tSastri MVC, Viswanathan B, Srinivasa Murthy S. Metal hydride. London/ New Delhi: Narosa Publishing House.1998."]}

International audience; Plusieurs études de modélisation et de simulation des réacteurs métal- hydrogène ont été effectuées afin d'évaluer leurs performances [1-7]. Ces études ont montré, que ladynamique de s tockage/déstockage de l'hydrogène est fortement contrôlée par les processus des transferts de chaleur dans le réacteur. Par conséquent, il est nécessaire de bien piloter ces transferts pour la meilleure dynamique du système. Dans la présente étude, des investigations expérimentales sont effectuées afin d'analyser la dynamique du réacteur équipé de plusieurs formes d'échangeurs de chaleur. Les mesures effectuées ont permis de voir l'effet de la forme d'échangeur sur le fonctionnement du réacteur.