Technology Research Of Thermoelectric Conversion Based On Sulfur-Iodine Thermochemical Cycle

The sulfur–iodine (S-I) thermochemical cycle is an efficient, economic, pollution-free andlarge-scale way for hydrogen production. Research has shown it is one of the most promisingoptions.The sulfur–iodine thermochemical cycle includes three reactions: Bunsen reaction, HIdecomposition and sulfuric acid decomposition.We researched for the optimal compromisedoperating conditions for the Bunsen reaction of S-I thermochemical water splitting,considering the key concerns of the S-I cycle: the liquid–liquid equilibrium (LLE) phaseseparation performance, the experiment was designed to determine the effect of reactantratio、temperature and pressure on the thermodynamic equilibrium of Bunsen reaction and theeffect of temperature、 pressure、 membrane reactor and vapor on the thermodynamicequilibrium of hydrogen iodide decomposition. Based on the results, the optimal operatingpoint and allowable operating window for the Bunsen reaction have been proposed: thepressure isStandard atmospheric pressure the temperature is80℃, iodine Molar percentage is0.45.Operating within this window makes it possible to avoid the side reaction and iodinesolidification. The most difficult separations of the cycle involve a mixture of hydrogen iodide,iodine and water (HIx).We used Factsage simulate HI catabolic reactions, simulated in a watervapor and membrane separation of HI decomposition rate balance. The results show that,when the temperature is higher than500℃, water vapor can promote HI decomposition;Through the membrane separation technology HI decomposition reaction rate can reached to77.1%, pressure had no effect on the reaction.Proton Exchange Membrane Fuel Cell（PEMFC）is developing very fast. It has manyadvantages, such as low operating temperature, start fastly, clearly, high power density, massproduction and so on.The paper established battery steady-state model by usingMatlab/Simulink, we do some research on gas pressure, temperature and relative humidity tothe battery characteristics.We found that that increasing electrode operating pressure, thetemperature, keep the reaction gas drying can improve the battery performance and batteryefficiency. However, with the larger current density and the temperature is higher than350K,efficiency decreased. In the course of the practical application of the battery, it needs to consider the efficiency and power requirements.The sulfur–iodine (S-I) thermo chemical cycle and Hydrogen fuel cell has attractedenormous interest internationally because of its promise of zero emission production ofhydrogen from water,its high efficiency, no pollution to the environment.They have broadmarket prospects.