MembersPage/BigBarrellEngine (2011-04-12 21:44:44)

Evaluating the feasibility of a large displacement 750 RPM powerplant engine.

Naturally aspirated, CR=16.5 for producer-gas (appr 50..55 Nm / liter of displacement equivalent to 4300 Watt on shaft, 4kWe on generator).

Gensets with similar engines usually achieve 50-80 kWe / ton of weight (the more common configuration is 1500 RPM engines with traditional crankshaft and connection-rods).


Cylinder liners - displacement

2 * 6 cylinders (160 liter total, appr 640 kWe). 2*4 (106 liter) would be another option.

Wet cyl liners or dry liners ?

ideas ?


Double roller

Rollers are 110..160 kN radial force depending on bore. (bearing for this is appr 150 mm OD, and 3kg)

See


Valves, valve-seat

Preferrably compatible with an engine family (Caterpillar, Cummins, whatever...).

intake valves

Exhaust valve:

Caterpillar valves

The availability of valve guides and seals must be considered also. (and possibly whole individual cyl heads if available).


Camplate

1 camplate at each end of the engine

Lifters

Mechanical or hydraulic ?

But see [Nissan lifter guts]. The internal diameter that counts (where the oil pressure acts during valve lifting) is much smaller even for the nissan, around 12mm.


Rockers

Rockers are probably the best choice for a camplate (instead of camshaft) engine.

Nice rocker arrangements:


Head


Oil pump


Coolant pump


Starter motor

The 3.4MW V20 GE Jenbacher engine (turbo-natural gas 1500 RPM is 21656 Nm, assuming 180 Nm /liter the total displacement can be around 120 liter) is started by 2 x 9 kW electric motor (24V each, ~400A current). It can be started by just 1 of the starters operating. A similar starter would seem suitable for the slightly bigger displacement barrell engine.

A [24V 7.8 kW caterpillar marine starter] 27.6 kg, $195

It is theoretically possible to use the syncronous generator as a starter

However, this (with the high current relays and added complexity) might be more costly (even with 400V but most likely with a 6-10kV generator) than a dedicated starter motor.