Alternative Power sources

Author

Waste Heat.

ashran111@hotmail.com

2005-11-08, 2:21 am

In our engineering class, we have been given a project to design a
device that is run off of a 10ish horsepower diesel engine (from the
1920s) that could be used to help in the agricultural evolution of
Ghana, our group came up with the idea to use the exhaust heat from the
diesel engine to heat (or even boil) water, to be used to aid in the
processing of palm kernel oil.
My problem is I have no idea how much 'waste' heat is a product of such
an engine, and I did not have very much luck finding anything, besides
a number that for all I know is completely arbitrary (diesel:
130000BTUs/gallon) I'm just in need of source of where I can get
information on this.

Thanks, help is greatly appreciated

Arnold Walker

2005-11-08, 5:21 am

ashran111@hotmail.com wrote:

> In our engineering class, we have been given a project to design a
> device that is run off of a 10ish horsepower diesel engine (from the
> 1920s) that could be used to help in the agricultural evolution of
> Ghana, our group came up with the idea to use the exhaust heat from the
> diesel engine to heat (or even boil) water, to be used to aid in the
> processing of palm kernel oil.
> My problem is I have no idea how much 'waste' heat is a product of such
> an engine, and I did not have very much luck finding anything, besides
> a number that for all I know is completely arbitrary (diesel:
> 130000BTUs/gallon) I'm just in need of source of where I can get
> information on this.
>
> Thanks, help is greatly appreciated
>
>

That would vary with the diesel engine somewhat...but assuming you had a
water cooled lister diesel of that size.It would be 290.0g/Kw.h roughly.

Being a steamer,I also know that, if you were to use this waste
heat(combined from exhaust and coolant) that for every 2545btu recovered
is a steampiston hp.
The motor block preheates your water to 160F.,then it is fed to the
exhaust heat exchanger.Which in turn adds 50-100F of heat to the
preheated water.
You using a water hopper,instead of a radiator?

Have you burnt palm oil in the diesel.....seem to remember missionaries
or someone with a palm oil powered diesel genset....somewhere near Manila.

That gallon should be wasting about 78,000btu.....

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AJH

2005-11-08, 9:21 am

On 7 Nov 2005 21:28:50 -0800, ashran111@hotmail.com wrote:

>In our engineering class, we have been given a project to design a
>device that is run off of a 10ish horsepower diesel engine (from the
>1920s)
>My problem is I have no idea how much 'waste' heat is a product of such
>an engine,

A rule of thumb for a modern diesel running at rated load is that 2/3
of the waste heat is in the exhaust and 1/3 in the coolant. As the
fueling is reduced less will be in the exhaust.

So if you average a conversion of thermal energy to motive power of
around 30% (on average we did worse) then your litre of diesel fuel
should end up:

motive energy ~2.5kWhr
coolant heat ~2.5kWhr(t) @ ~95C
exhaust heat ~5.5kWhr(t) @ ~450C
total 10.75kWhr/litre

How much you can sensibly use is another matter.

AJH

Dave Hinz

2005-11-08, 9:21 am

On 7 Nov 2005 21:28:50 -0800, ashran111@hotmail.com <ashran111@hotmail.com> wrote:
> My problem is I have no idea how much 'waste' heat is a product of such
> an engine, and I did not have very much luck finding anything, besides
> a number that for all I know is completely arbitrary (diesel:
> 130000BTUs/gallon) I'm just in need of source of where I can get
> information on this.

Well, don't overcomplicate things. You either get usable output, or
heat. BTU content of the fuel gives you the total. Calculate fuel used
for usable power, and the rest is "waste" heat.

2005-11-08, 3:21 pm

In article <1131427730.264908.300710@g14g2000cwa.googlegroups.com>,
ashran111@hotmail.com wrote:

> In our engineering class, we have been given a project to design a
> device that is run off of a 10ish horsepower diesel engine (from the
> 1920s) that could be used to help in the agricultural evolution of
> Ghana, our group came up with the idea to use the exhaust heat from the
> diesel engine to heat (or even boil) water, to be used to aid in the
> processing of palm kernel oil.
> My problem is I have no idea how much 'waste' heat is a product of such
> an engine, and I did not have very much luck finding anything, besides
> a number that for all I know is completely arbitrary (diesel:
> 130000BTUs/gallon) I'm just in need of source of where I can get
> information on this.
>
> Thanks, help is greatly appreciated
>

The "Rule of thumb" for this is 1/3 of the energy in the fuel is produced
out the output crankshaft, 1/3 of the energy is produced in the cooling
system, and 1/3 of the energy is produced up the exhaust stack.
Recovering the cooling system energy can be as good as 75% efficent.
Recovering the exhaust energy can be as good as 45% efficent at best.
Recoving crankshaft is near 95% efficent baring major friction losses.

Me

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