Performance of a solid oxide fuel cell CHP system coupled with a hot water storage tank for single household

In this paper a solid oxide fuel cell (SOFC) system for cogeneration of heat and power integrated with a stratified heat storage tank is studied. Thermal stratification in the tank increases the heat recovery performance as it allows existence of a temperature gradient with the benefit of delivering hot water for the household and returning the coldest fluid back to SOFC heat recovery heat-exchanger.
A model of the SOFC system is developed to determine the energy required to meet the hourly average electric load of the residence. The model evaluates the amount of heat generated and the amount of heat used for thermal loads of the residence. Two fuels are considered, namely syngas and natural gas. The tank model considers the temperature gradients over the tank height.
The results of the numerical simulation is used to size the SOFC system and storage heat tank to provide energy for a small household using two different fuels. In particular it was shown that in the case of syngas, due to larger system heat output, a larger tank volume was required in order to accumulate unused heat over the night.
The detailed description of the tank model will be useful to energy system modelers when sizing hot water tanks.