Thermochemical recuperation by ethanol steam reforming: Thermodynamic analysis and heat balance

This article considers the scheme of fuel-consuming equipment with a thermochemical heat recuperation system by using ethanol steam reforming. The main concept of thermochemical recuperation (TCR) is the transformation of exhaust gases heat into chemical energy of a new synthetic fuel that has higher calorimetric properties such as low-heating value. Thermochemical recuperation can be considered as an on-board hydrogen production technology. To determine the efficiency of the thermochemical recuperation system, the thermodynamic analysis via Gibbs free energy minimization method was performed. The software Aspen-HYSYS was used for the thermodynamic analysis. The heat flows were calculated for a wide temperature range from 500 to 1000 K, for steam-to-ethanol ratio from 1 to 3, and for various pressures of 1, 5 and 10 bar. The results of the thermodynamic analysis were compared with the experimental results and the results of the thermodynamic analysis performed by other authors. All obtained results are in a good correlation. In the first law energy analysis was found that for a high steam-to-ethanol ratio (above 3), to perform thermochemical recuperation an external heat must be supplied to the TCR system. The heat deficit for steam-to-ethanol ratio 3 is from 1 to 2 MJ/kg_EtOH in the temperature range from 500 to 1000 K.