[September 2006]  An innovative new engine with significantly improved fuel efficiency is being developed by a British team.

The Lindsey Engine™ was designed by Steve Lindsey, who is now the Technical Director of Lontra Ltd, the company developing and exploiting the technology. Lindsey developed his design over the past 10 years, and Lontra will later this year complete the initial prototype of the new geometry – as a compressor.

The patented design is entirely innovative, and the company remains tight-lipped about the details. However, it is rotary in design and operates with the induction/compression and combustion/exhaust strokes taking place in separate chambers. The nature of the design means that it remains highly compact, and has the ability to use the Miller/Atkinson cycle.

The principal benefit is improved efficiency. Modelling indicates a part-load efficiency gain of up to 37% over a traditional engine (at 2000 rpm / 2 bar bmep). With optimisation, the full load efficiency improvement is 8% (rising to 21% against an engine unable to run stoichiometrically). The engine is also highly compact, with a power density assessed at 75kw/l(100hp/l). The engine requires no exhaust tuning, enabling close catalyst location to create faster light off and lower emissions. It has potential with a range of fuels, and in particular advantages with hydrogen, where the tendency to auto-ignition can be successfully managed. In common with other rotary designs, it has the potential to run at high speeds.

The design has a wide range of potential applications. With only the induction/compression chamber in-build it becomes a compressor. This has the ability to vary capacity without the need for sophisticated power systems controls to offer the same benefits as Variable Speed Drive, but at a reduced cost. The potential for coatings within the compression chamber opens the possibility of use with aggressive gases, whilst a large swallowing capacity for its size makes it an appealing option where space or weight is a consideration, for instance automotive superchargers.

As an engine, the design has applications where efficiency is of importance and its potential to vary power and heat outputs on demand with a smaller than normal reduction from peak efficiency makes it particularly appropriate for Combined Heat and Power. It will be the ideal unit to fit or retrofit to new or existing shell and tube boilers, which are the standard in commercial and industrial areas, as a hot combustion air/power generator to both economic and environmental advantage. The small size and quiet operation also makes it a potential technology with mass market micro-CHP. . However the mechanical simplicity and compactness of the engine has led Lontra to initially focus their attention on markets traditionally the preserve of two stroke units (the Lindsey engine effectively runs a 4 stroke cycle). Without the induction/compression chamber the design has potential as an expander.

Lontra has worked for two years with Mahle Powertrain, who have undertaken extensive GT Power and other modelling. Mahle is currently completing a detailed design and modelling phase before prototype construction. Lontra has also created two initial test-beds, and is working with other British engineering specialists. Various projects with UK universities are also planned. The company also benefits from guidance on request from a number of selected advisors including the author.

Lontra has financed development to date through a combination of investment and grants. Investors include Lontra’s founders and Imperial Innovations (the commercial arm of Imperial College). Lontra is the first external company in which Imperial Innovations has ever invested. The company has also benefited from a DTI Research Grant, a Development Grant from the London Development Agency and the support of the Carbon Trust, through its incubator scheme.

Fred Nash

Back to top