Enhua Wang
Beijing Institute of Technology, China
Title: Improving efficiency of a Kalina cycle by controlling condensation pressure for low-grade energy utilization
Biography
Biography: Enhua Wang
Abstract
Kalina cycle is a promising technology for power generation from low-temperature heat sources. Conventional air-cooled Kalina cycle for geothermal power plants are designed with a fixed condensation pressure determined by the local summer ambient temperature, which causes a huge amount of exergy destruction when air temperature drops. If the power plant can vary the condensing temperature with the ambient conditions, the plant’s annual average thermal efficiency would be improved. To address this challenge, this paper proposes a method to improve the energy efficiency of a Kalina cycle by adjusting its condensation pressure in situ to match the varying ambient temperature. A mathematical model is set up based on its working principle and then a numerical program is developed to analyze the cycle performance under various conditions. The dynamic condensation pressure adjustment in accordance to the changing ambient temperatures has been numerically demonstrated. Its effect on the system performance of a Kalina cycle over a year is then evaluated. The results indicate that, through matching the cycle with the changing ambient temperature via adjusting condensation pressure, the Kalina cycle can achieve much better annual average thermal efficiency than a conventional Kalina cycle without any adjustment if the mass fraction of ammonia-water mixture is selected in the right interval. For low-temperature geothermal power generation, this method can improve the energy efficiency evidently.
Recent Publications
1.Zhang X, He M, Zhang Y (2012) A review of research on the Kalina cycle. Renewable and Sustainable Energy Reviews 16: 5309-5318.
2.Hua J, Chen Y, Wu J (2014) Thermal performance of a modified ammonia-water power cycle for reclaiming mid/low-grade waste heat. Energy Conversion and Management 85: 453–459.
3.Saffari H, Sadeghi S, Khoshzat M, Mehregan P (2016) Thermodynamic analysis and optimization of a geothermal Kalina cycle system using Artificial Bee Colony algorithm. Renewable Energy 89: 154-167.
4.Mergner H, Weimer T (2015) Performance of ammonia-water based cycles for power generation from low enthalpy heat sources. Energy 88: 93-100.
5. Wang E, Yu Z (2016) A numerical analysis of a composition-adjustable Kalina cycle power plant for power generation from low-temperature geothermal sources. Applied Energy 180: 834-848.
