| Description |
This dissertation focuses on the operation and analysis of thermochemical energy storage systems based on the reaction of magnesium chloride salt and ammonia gas, to understand the heat and mass transfer limitations of the solid-gas reactions. Two experimental setups were prepared to study the propagation of the reaction and performance of the thermochemical batteries, as well as to measure the thermophysical properties of the reactive compound such as thermal conductivity, porosity, and permeability. Additionally, a numerical simulation code was developed to recreate the experimental results computationally and study the reactions further. The performance of thermochemical batteries was analyzed using the two experimental setups and the numerical simulation code. A compound of magnesium chloride and graphite with different densities was used in the experiments. It was observed that for the low-density reactive compounds, the gas could easily propagate through the reactor and the progress of the reaction depended on the heat transfer through the reactor. On the other hand, for the high-density salts, the progress of the reaction was dependent on the mass transfer through the reactive compound. Other experiments showed that it is possible to control the temperature and the duration of the reaction by controlling the mass flow rate of ammonia gas, although doing so would change the propagation of the reaction inside the reactor. Moreover, limiting the mass flow rate of ammonia gas in a multicell iv thermal battery can cause the cells to differentiate in their absorption progress. However, due to the low permeability of the salt, the performance of the multicell thermal battery was not satisfactory. The material properties obtained by the experiments and the numerical simulation code were used in a parametric study on the geometry and dimensions of the reactors. It is shown that heat absorption using internal tubes gives better control over the reaction and creates more uniform heat release rate. Eventually, the concept of a nonidling heating and air conditioning system for a long-haul truck based on the thermal battery idea is designed. Similarly, a solar thermal battery is designed to absorb and store solar thermal energy. This system can work as a heating and air-conditioning system for a small building. The conceptual designs discussed in this report are the first step in designing practical thermal batteries. |
