Exergy Analysis of Direct and Indirect Combustion of Methanol by Utilizing Solar Energy or Waste Heat

Abstract

The growing concern for energy, economy, and environment calls for an efficient utilization of natural energy resources for obtaining useful work. An important thermodynamic aspect in the assessment of the overall energy economy of any physical process is the combined energy and exergy analysis for the identification of process irreversibilities. This paper demonstrates the application of exergy analysis to gain a better understanding of methanol decomposition by using solar energy, based on a comprehensive kinetic model of methanol decomposition employing BASF K3−110 catalyst, then utilizing it in a power cycle and also an internal combustion engine. A comparison is presented between the direct and indirect combustion of methanol. The predictions in this study showed that combining solar thermal energy and methanol decomposition can upgrade the lower level of solar thermal energy to a higher one of chemical energy with syngas and decrease the chemical exergy loss associated in the indirect combustion of methanol. The exergetic efficiency could also be increased by about 6−7% compared with the conventional combustion of methanol.