Performance Prediction of a Practical Low-Pressure-Ratio Highly Efficient Split-Cycle Recuperated Engine
Journal Article
03-16-01-0007
ISSN: 1946-3936, e-ISSN: 1946-3944
Sector:
Topic:
Citation:
Mivelle, G., Eldakamawy, M., Boudreau, P., and Picard, M., "Performance Prediction of a Practical Low-Pressure-Ratio Highly Efficient Split-Cycle Recuperated Engine," SAE Int. J. Engines 16(1):113-128, 2023, https://doi.org/10.4271/03-16-01-0007.
Language:
English
Abstract:
Split-cycle recuperated engines are promising candidates to compete with
hydrogen-based fuel cells for high-duty cycles. They can potentially achieve
similar, or even higher, efficiencies at the cost of historically cheap piston
engines. However, existing approaches are either limited in efficiency or
difficult to develop, mainly because of the challenges around the
high-temperature expansion piston. This article presents a practical
architecture of a low-pressure-ratio, recuperated split-cycle engine with a
contact-free expansion piston using labyrinth seals supported by thermodynamics
and numerical modeling. The engine operates under a regenerative dual Brayton
cycle to combine the benefits of constant pressure heat recuperation and
near-constant volume combustion. Thermodynamics results reveal pre-compressing
the residual mass in the expansion cylinder before intake is crucial. A 0D
transient model integrating main losses is implemented to explore the design
space and maximize efficiency through a numerical design of experiments. The
blowby in the expansion cylinder is the main loss but remains acceptable for
relatively tight clearances. An indicated efficiency of 60% is predicted for a
cycle pressure of 20 bar and an expansion piston exhaust temperature of 1250 K.
The predicted indicated power density of 6.5 kW/L is relatively low but in the
range of micro-combined-heat-power diesel engines.