alt.energy.renewable

"Morris Dovey" wrote in message
news:47FA6F0F.7115CE33@iedu.com...
> Mike wrote:
>
>> It's funny that some 30 years ago we spent many weeks in lectures and
>> with our noses in books studying thermodynamics and often looking at
>> PV diagrams for heat engines. Then some months later we came to test
>> a real engine coupled to a test indicator and dynamometer. The graph
>> roughly had the idealised shape that all the text books illustrated -
>> by roughly I really mean very, very roughly, some might suspect that
>> technical text book authors had never ever tested a real engine :)
>
> Mike...
>
> Can you tell me anything about the test set-up that allowed you
> to see the real graph? Is there a way for me to use my
> oscilloscope to watch what's going on in a prototype engine?
>
> I didn't take thermodynamics, but I dimly recall studying gas
> laws in HS. Now I'm wishing I had (or had time to do so now.)
>

While not exactly the same, old reciprocating steam engines such as railroad
units would sometimes be tested using literally a sort of clip-board,
graph-paper and a pressure gauge type device with a pen on it. Mounting the
'clip-board' on the piston rod, connecting the pen/gauge to the cylinder
test-cock and arranging it to record the pressure on the paper from side to
side as the piston moved back and forth. Obviously this only worked in the
shop at very slow speeds :-)

daestrom