Implementation of a waste heat recovery prototype facility based on the Rankine cycle with a twin-screw expander

Abstract

Considering the energy needs of developing countries, thermal power plant facilities are necessary for power generation. However, usable thermal energy is lost because the necessary technologies to exploit the waste heat from industrial processes have not yet been implemented. In this sense, the present analysis shows the experimental study of a prototype Steam Rankine Cycle energy system. The prototype uses the residual heat of the combustion gases from one of the generators installed in a thermal power plant as a heat source, the maximum temperature of these gases is 320 °C. This prototype is considered the first in the region to perform heat recovery with a power cycle with water as the working fluid. Considering the country’s economic constraints, the prototype was built using a 20 kW twin-screw compressor modified to function as a turbine. This prototype aims to increase the overall performance of the generating unit. For the characterization of this prototype plant, energy and exergetic efficiency analysis was carried out using the experimental data. The application showed that the measured efficiency of the twin-screw expander was low at 18.44 %. In contrast, the maximum expander work was 15.81 kW, the overall cycle efficiency was 3.52 %, and the exergetic efficiency was 5.45 %.