ISBN 9783843951661

978-3-8439-5166-1, Reihe Energietechnik

Moritz Daniel Gleinser
A Batch–Evaporation Power Cycle for Low-Temperature Heat Sources: Thermodynamics and Economics

243 Seiten, Dissertation Technische Universität München (2022), Softcover, A5

Zusammenfassung / Abstract

There are no simple yet high-performing power cycles for low-temperature heat sources to date. This work screens the current options and presents a detailed thermodynamic and economic analysis of a promising batch-evaporation power cycle: the MWM Cycle. First, a theoretical analysis of this dynamic cycle is presented. Second, a dynamic simulation model is introduced, covering heat and mass transfer effects and the influence of thermal inertia on the dynamic behavior. At last, an economic evaluation by means of static and dynamic methods, most importantly the annuity method, is performed with different reference conditions and working fluids. The cycle analysis showed that the dynamic batch evaporation allows for an almost perfect temperature match between heat source and working fluid without the need for complex components. At the temperature of 100 °C, the second law efficiency of the MWM Cycle outperforms a simple ORC by about 39 % even with the environmentally recommended "replacement–fluid" R1234ze(E). With regard to the economic figures, the annuity of the MWM Cycle could only compete with the ORC by dismissing the originally estimated reduced operation hours (MWM vs. ORC: +25 %). The overall comparison of different temperatures, working fluids and refund rates showed that the MWM Cycle is a thermodynamically promising and feasible cycle. However, at low temperatures it is, like the ORC, hardly profitable with the electricity prices and regulatory conditions used in this work.