Assessment of the Newcomen engine’s development potential as heat engine for low temperature waste heat

Abstract

There is a large but mostly unused energy resource available from low temperature waste heat with temperatures of 80–150°C. The lack of a cost-effective technology prevents the generation of power from this potential. Recently, the Condensing Engine, which employs the condensation of steam and the arising vacuum as the driving force, had been developed to address this problem. Its simplicity and the use of water as working fluid promises cost-effectiveness. In the context of this work, it was decided to investigate the Newcomen Engine to assess its potential. This engine is usually neglected because of is low efficiency, thought to be caused by the continuous cooling and re-heating of the cylinder. A thermodynamic model of the engine was developed. Surprisingly, the model indicated that 78% of the heat losses are caused by the re-heating of the injection water and only 22% by the cooling and re-heating of the cylinder. This finding allowed to conceptualise a new engine, the Internal Condensation Engine, where plastic material for the cylinder and the forced ejection of the water minimise losses. The engine would have a similar or better efficiency than competitive technologies whilst being simpler, and therefore more cost-effective.