Enhancing power generation capacity of geothermal power station by integrating Trilateral Flash Cycle (TFC)

In spite of the energy crisis, a large amount of low-grade heat (below 100 oC) is being wasted for the lack of cost-effective technology.  Recovery or utilization of low-grade heat is drawing the attention of the researcher what is still a big challenge. Organic Rankine Cycle (ORC) is the widely used conventional system for heat-to-power generation where phase change of working fluid occurs during the addition of heat that decreases the efficiency of the system. Therefore, in this project, an analytical as well as an experimental study have been performed for power generation using Trilateral Flash Cycle (TFC) based heat engines which has been considered more effective for low-grade heat to power generation than Organic Rankine Cycle (ORC) based system. The focus of the study was to develop a power generation system in a cost-effective manner. The considered TFC based heat engine consists of a Converging-diverging (CD) nozzle and impulse turbine setup as an expander and developed a simulation model with experimental validation. For this study, an experimental setup was developed in consist of a CD nozzle, a Pelton type impulse turbine coupled with a generator, a plate type heat exchange and a shell and tube type condenser and a pump. The experiment was performed under three different temperatures (64, 67 and 72 oC) and Iso-pentane was considered as the working fluid with a flowrate of 2.4 to 4.6 l/min. The experimental results showed only 2% deviation from the analytically predicted performance at 64 oC operating temperature and concluded that having only 50% isentropic efficiency, the TFC system can produce 1.5 to 2 times more power than ORC system from same heat sources. Moreover, for only 25% higher cost of installation than ORC, the TFC system has a simple payback time of less than 5 years where 10 years of payback time is considered economical for such type of system with more than 20 years of running life.