Thermodynamical model of an atmospheric steam engine

Autor: Bernardo Luiz Harry Diniz Lemos, Rodrigo de Lima Amaral, Cesar Monzu Freire, Vítor Augusto Andreghetto Bortolin, Julio Romano Meneghini
Rok vydání: 2021
Předmět:
Zdroj: Journal of the Brazilian Society of Mechanical Sciences and Engineering. 43
ISSN: 1806-3691
1678-5878
DOI: 10.1007/s40430-021-03209-9
Popis: Atmospheric steam engines (ASE) were the first practical machines to convert thermal energy to mechanical work. However, their low efficiency and specific power relegated them to oblivion. Nevertheless, the recent urge for harnessing energy from heat sources with low to medium temperatures (100 to 150oC), especially in renewable sources and waste heat, renewed the interest in this technology. However, since ASEs were constructed before the development of thermodynamics theories and concepts, there is a lack of studies on their operation cycle and optimization. Therefore, this work proposes a complete thermodynamical model for the adiabatic and isothermal atmospheric steam cycle that uses real gas data. The model is constructed to accommodate the forced expansion of the low-pressure steam. The results show that the adiabatic cycle is more efficient than the isothermal cycle and also that the amount of heat needed to keep the expanding steam at a constant temperature is prohibitive for practical applications. The data also indicate that with a moderate expansion ratio (r = 4) the adiabatic engine has a theoretical efficiency of 14%. The maximum efficiency obtained was 17,67% for r = 15. Furthermore, overheating presented a minor influence on the ASE theoretical efficiency.
Databáze: OpenAIRE
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