Nickel-hydrogen cells promise to provide a 50 to 100 percent improvement in energy density over present spacecraft nickel-cadmium batteries combined with longer life, tolerance to overcharge and reversal and the possibility of state-of-charge indication. In order to realize the full potential of nickel-hydrogen batteries, however, one of the design considerations is the proper distribution and removal of heat generated within the cells. Failure to accomplish uniform heat distribution can lead to premature failure due to electrolyte distribution and evaporation problems, local decreases in efficiency, and difficulties with uneven current density.; The purpose of this research was to investigate the heat generation and transfer rates in nickel-hydrogen cells and the resulting temperature distribution during cyclic operation. A detailed thermal model was developed to predict heat generation rates and cell temperatures and verification of the model was carried out by evaluating a Ni-H(,2) cell under various cyclic conditions.; The procedure followed in this investigation was to cycle the cell under controlled conditions and measure the charge efficiency as a function of the state-of-charge. The efficiency values were then used with the actual cell voltage, current and pressure obtained under similar conditions to calculate the heat generation rate as a function of time. The heat generation profile served as input to a three dimensional thermal model of the cell and a computerized numerical solution resulted in the prediction of cell temperatures. Correlation of the predicted and measured temperatures was obtained through a unique experiment which made use of a specially designed calorimeter.; Heat rates were measured using the calorimeter which completely enclosed the cell, permitting the continuous measurement of heat flux from the cell and caps as well as the cylindrical section where the stack is located. The temperature distribution over the cell surface was measured by twenty thermocouples located within the calorimeter and an additional ten thermocouples which were located on the terminals and surface of the cell.; The sensitivity of the model was evaluated for various parameters such as the capacitance of the calorimeter, variations in heat sink temperature, contact resistance, and convection heat transfer. It was determined that the model was relatively insensitive to changes of the magnitude experienced during the investigation for each of the parameters with the exception of the contact resistance. In that case, inclusion of contact resistance in the model was found to improve the agreement with the experimental results. Correlation of the measured temperatures and heat rates with those predicted by the model verified the applicability of the model for potential design studies and analysis of other metal-gas cells.
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