Exergoeconomic analysis of a novel small‐scale CHP system for rural electrification in Uganda

Abstract

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.In a world with finite natural resources and increasing energy demand by developing countries, it calls for energy researchers to come up with systematic approaches for improving the design of energy systems and reducing the impact on the environment. Exergoeconomics is a powerful tool for understanding the interconnections between thermodynamics and economics, and thus viewed as an exergy‐aided cost minimization technique crucial to the design and operation of a cost effective energy system. In this paper, the exergoeconomic analysis is applied to a small‐scale CHP system integration consisting of a downdraft gasifier, producer gas combustor/heat exchanger, indirectly fired gas turbine and heat recovery steam generator. Appropriate thermodynamic expressions, and cost analysis formulas/theorems and energy investment scaling equation obtained from literature were applied. The investigated CHP system that has the potential of providing relatively higher efficiency and minimal operational difficulties, and thus attractive for rural electrification in Uganda. Exergy analysis revealed that 56.8% of the available exergy of the fuel is lost in the CHP system due to inherent irreversibilities within the system components. The study further revealed that the heat exchanger exhibits the highest exergetic loss cost of 3.555($/h) and thus consideration of modifying the heat exchanger model to reduce exergy loss is paramount.