{'fraction_non_alphanumeric': 0.019956850053937433, 'fraction_numerical': 0.0005393743257820927, 'mean_word_length': 4.870253164556962, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Unresolved Issues in Fuel Cell Modeling

A fuel cell is an electrochemical device that converts the stored chemical energy in fuel directly into electrical energy. The fuel is not burned in a flame, as in conventional power systems; rather, it is electrochemically oxidized. Therefore, the maximum efficiency of a fuel cell is not limited by the Carnot cycle, which limits many conventional power systems such as the steam turbine, the gas turbine, the heat pump, and the internal combustion engine. The fuel cell is very similar to a battery in that both convert chemical energy into electrical energy. Fuel cells differ from batteries in that fuel cells oxidize fuel that is supplied externally, thus enabling them the potential to run continuously as long as there is a fuel source. In contrast, a battery has a limited life per charging cycle, and cannot be used when it is recharging. A schematic of a general fuel cell is presented in Figure 1. A fuel cell generally functions as follows: electrons are released from the oxidation of the fuel at the anode and flow over an external circuit while the protons (or ions) pass through an electrolytic layer. The reduction reaction at the cathode involves electrons, protons, and an oxidant that produces a byproduct, usually water. Other byproducts can be produced, depending on the fuel and the oxidant. Typical fuels are hydrogen, carbon monoxide, and hydrocarbons. The hydrogen and carbon monoxide fuels may be produced from catalytically processed hydrocarbons or processed ammonia. Oxygen is the standard oxidant because it is readily available from air; however, other oxidants such as the halogens can be used when high efficiency is crucial. The desired output of a fuel cell is the largest current over the highest electrical potential, because this results in the highest production of power.