Analysis of Marine and Industrial Condensing Steam Engine Performance for Low-Grade Waste Heat Recovery

A Practical Solution in an Era of Super Technologies

Abstract

Low-grade waste heat and low temperature sources are typically utilized to make electricity and mechanical power by the application of Organic Rankine Cycle (ORC) systems. However, the low-pressure condensing steam engine (CE) using a naturally abundant and environmentally friendly working fluid, water, may provide the solution to fulfil the requirements of many power systems with a working temperature of 100°C and atmospheric steam pressure, and even lower. CEs were common in early steam engine designs and gradually became low-pressure stages of higher-pressure, multistage engines as inlet temperatures and pressures increased. Müller & Howell recently republished results from tests of small engines built in the late 19th Century, which show a second law efficiency of 24.7% [1, pp. 29]. However, larger and more developed designs achieved a second law efficiency of 52.5%. With modern design and manufacturing methods applied, the CE’s adequate efficiency and absence of exotic materials, combined with the lower capital, operating, and disposal costs of water bring this technology to the forefront to derive more utility from cement, steel, oil & gas, marine, and industrial thermal processes as well as utilize primary sources such as geothermal and low-grade solar thermal energy.