PM Research Solar Engine #3

Oh yeh? Where? If you think it is efficiently simply only just running itself, it must be - by your calculations - 100% efficient.

Now that is “tosh”.

No doubt as others have tacitly mentioned recently, you will want the last word - rubbish or not - so I’ll leave it here, for you to dig an even deeper hole for yourself.

Err, I think is this an misplaced argument about a simplified formula:

EFFICIENCY = WORK DONE divided by the ENERGY INPUT

which isn't the same as:

EFFICIENCY = USEFUL WORK DONE divided by the ENERGY INPUT

In the second formula the engine's efficiency is zero, but this definition ignores that 'Useful Work' is done operating the engine's valve. The first formula allows all WORK DONE to be taken into account, and that isn't zero as NDIY postulated. The bearings, piston and valves aren't frictionless, and the engine moves the mass of the piston, conrod, valve-rod and flywheel (force x distance). The flame outside the engine also does work by lifting hot air!

How the formula is applied isn't the only issue. Motors don't have a single 'efficiency', rather they have a range of efficiencies that vary depending on how they are operated: unloaded efficiency is not the same efficiency at overload and peak efficiency occurs somewhere in the middle, at some particular combination of RPM and load. Torque, Power and Efficiency all vary with load over a motor's operating range.

Dave

Thank you, Dave, for applying some reasoning.

Now … to avoid me ‘having the last word’ would someone kindly make a post.

MichaelG.

Happy to oblige.

My only experience with flame gulpers was watching one at an exhibition then smelling strongly of paraffin afterwards due to the spitting back effect of the burner.

Edited By V8Eng on 22/10/2022 14:35:59

This engine easily has power to run steam engine type accessories.

If it can run a small dynamo, it would be relatively simple to measure its power - with one caveat - using a resistor (e.g. a filament lamp), voltmeter and ammeter.

The caveat of course is this does not account for the energy expended within the dynamo, so it is testing the system, not the engine.

I was assuming the dynamo loss there would be quite small compared to the engine's rather obvious external-combustion flaw, so a full efficiency calculation - which would need you knowing the calorific value and quantity used, of the fuel - would still be a fair estimate.

I wonder if anyone has succeeded in making a brake-type dynamometer work in model scales?

(I recall a school physics experiment to measure the efficiency of a filament lamp "bulb". [Yes I know 'lamps glow, bulbs grow'.]. The lamp - a 6V one I hasten to add - was waterproofed and lowered into a small beaker of water containing a thermometer. I recall the electricity to light efficiency was well under 10%... >90% of the W being the heat.)