Exergoeconomic analysis of cascaded organic power plant for the Port Harcourt climatic zone, Nigeria

Abstract

This paper presents the exergoeconomic analysis of a 100 kW solar driven organic Rankine cycle (ORC) power plant for the Port Harcourt climatic zone, latitude 4.5–5.5°N and longitude 6.5–7.5°E, at an ambient temperature range of 23–31°C. A cascade cycle of R134a and R290 working fluids was considered for the proposed plant. The relationships between thermodynamic properties and characteristics were formulated and numerical solutions obtained in the Microsoft Excel and MATLAB environments for the assessment of the performance of the plant. The size and mass flow rate of water through the flat plate solar collector, mass flow rates, efficiencies, and other relevant parameters of the cycles were determined. The energy and exergy efficiencies of the proposed plant, at the optimal collector operation, are 18.92 and 21.61%, respectively. The total capital investment, levelized cost of energy, payback time and the earning power of the investment were estimated to be 352 US$/kW, 0.0072 US$/kWh, 2 years 7 months, and 14.3%, respectively. The unit cost of electricity obtained did not consider energy storage, which would have significantly increase the unit cost of electricity. The component exergoeconomic factors, the relative cost difference and the average specific cost of revenue of the plant were also determined. These results might be particularly useful to researchers and energy engineers who might wish to optimize the system for effective electricity generation. From simulations performed, it is viable to install an ORC power plant in the climatic zone considered in this study.

Keywords

• renewable energy
• flat plate solar collector
• refrigeration
• organic rankine cycle power generation
• exergoeconomic analysis