Computational performance of a-100 kW low pressure turbine to recover gas turbine exhaust energy

Abstract

Low Pressure Turbine (LPT) was designed to recover exhaust energy from Internal Combustion (IC) engine. The LPT is located downstream retrieved exhaust heat energy from combustion after flowing through the high pressure turbine (HPT). The work output obtained from the exhaust energy is used to drive an electric generator with power output of 1.0kW. These was not done by commercial turbine as the low efficiency resulted when operated. The main purpose of this project is to develop a scaling model for LPT with power output up to 100kW. An existing LPT that was designed with output of 1.0 kW used as guideline to upscale the turbine. Scaling factor was obtained by comparing the baseline with power output. The turbine performance was analysed by using a commercial Computational Fluid Dynamic (CFD) ANSYS CFX. The study found that the scaling factor f, of 10 can be used to produce a 100kW at passage. Thus, the geometrical parameter will be scaled accordingly. The rotational speed is reduced from 50,000 rpm to 5,000 rpm. The CFD analysis found that 81% of total-static efficiency, ht-s at velocity ratio VR, of 0.68 and the Pressure Ratio PR, of 1.12 producing power of 119.88 kW which nearest with the design point which is at 100 kW. Despite the LPT swallowing capacity is increased by 50 times, the LPT is still limited by the operational choking Pressure Ratio, PR limitation which is 1.4.

Keywords

• low pressure turbine
• electric-turbocompounding
• exhaust energy recovery
• turbine scaling