The engines

The crowd funding project engine

So far, we have built and tested a small, 50 Watt engine with a piston diameter of 50 mm (2″), and a stroke of 150 mm (6″). Now, we want to go bigger and build, test and run a 1 kW engine with a piston diameter of 160 mm, and a stroke of 220 mm. The design expansion ratio is n = 1:3, the design power output approximately 1 kW at 60 rpm.

For the first design, we changed plans and decided to go for a vertical arrangement similar to Davey’s engine. The fact that we have an engine as model makes the design much simpler.

Vertical engine
1 kW engine, vertical configuration

With an overall height of 1.1 m (4 ft ), and a width of appr. 0.9m (3 ft) the engine is fairly compact. Compared with a beam engine, the vertical configuration is smaller and does not have the problems connected with the parallelogram and the top cylinder seal. The design incorporates several improvements:

  1. The engine has a spray condenser, to reduce the size.
  2. The flywheel has a 1:3 gearing, reducing the necessary diameter and improving its effect on power output quality.
  3. Power take-off is a DC permanent magnet  generator with a potentiometer as load dump.

We are also looking at air-flow cooling (or, technically speaking, heat rejection) where we want to try out Venturi cooling which may allow to create temperatures below ambient without a refrigerator. Theory indicates that a temperature drop of 10-12 K below ambient should be possible, and first experiments showed a 5.7 K drop. This however will require further work.