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Author Topic: Super efficient diesel/bio fuel 4kw generator design.  (Read 9002 times)

TommeyLReed

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Super efficient diesel/bio fuel 4kw generator design.
« on: June 02, 2014, 12:30:26 PM »
This is a simple generator I design for my side work and emergency power.

I got a 6hp diesel engine on Ebay for $550.00 with shipping.

I had a 10kw Harbor Freight generator head, it cost $299.00+tax

For a total of $866.94 I have a generator that runs at 2800 rpms and the generator head at 3600rpm or a ratio of 1:1.25

This unit runs for 8 hours at 75% load with a 3.5l or .92gal fuel tank.

6hp diesel engine:

http://www.ebay.com/itm/NEW-6HP-SMALL-DIESEL-ENGINE-WITH-ELECTRIC-START-6-HP-/180700361816?pt=LH_DefaultDomain_0&hash=item2a1294b458

10kw generator head:

http://www.harborfreight.com/10000-watts-max-7200-watts-rated-belt-driven-generator-head-45416.html

My unit:

https://www.youtube.com/watch?v=yLaHcYUbEBc

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MarkE

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Re: Super efficient diesel/bio fuel 4kw generator design.
« Reply #1 on: June 02, 2014, 12:47:08 PM »
I always enjoy your projects.  If only Gary would decide to come back on the air!

The back of my napkin:  0.92 gallons is 125MJ, at 8 hours run = 4.33kW equivalent fuel input = 5.85 hp equivalent fuel input.  If you are getting 75% of 6 hp output then you are breaking efficiency records for inexpensive normally aspirated diesel engines.  So you probably want to double check your numbers.

If you got that 8 hour run time on 0.92 gallons with a 1.5kW or greater electrical load then you would be getting 32% or better LHV utilization from the fuel which would be very good.  10kW - 20kW commercial diesel gensets tend to top out around 40% LHV utilization.
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TommeyLReed

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Re: Super efficient diesel/bio fuel 4kw generator design.
« Reply #2 on: June 02, 2014, 02:53:24 PM »
I will do a run test and check my calculation again, thanks.

I will do a video to show true output verse input of diesel fuel.
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MarkE

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Re: Super efficient diesel/bio fuel 4kw generator design.
« Reply #3 on: June 02, 2014, 02:54:52 PM »
Sounds great.
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TommeyLReed

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Re: Super efficient diesel/bio fuel 4kw generator design.
« Reply #4 on: June 02, 2014, 03:10:32 PM »
I would like to add that diesel has about 130,000-135,000 btu's, gasoline is between 120,000 to 125,00 btu's

125,000 btu's x 40%=50,000 btu's
50,000btu / 3.41=14,662 total watts or 14.662kw
14.7662kw/8hr=1.83kw per hour

This is at 50% load data.


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TommeyLReed

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Re: Super efficient diesel/bio fuel 4kw generator design.
« Reply #5 on: June 02, 2014, 03:15:24 PM »
125,000 btu's x 75%=93750 btu's
93750btu / 3.41= 27,892total watts or 27.892kw
27.892kw/8hr=3.436kw per hour

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MarkE

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Re: Super efficient diesel/bio fuel 4kw generator design.
« Reply #6 on: June 02, 2014, 04:19:00 PM »
Quote
125,000 btu's x 40%=50,000 btu's
50,000btu / 3.41=14,662 total watts or 14.662kw
14.7662kw/8hr=1.83kw per hour

This is at 50% load data.
The units are not quite right:

1 BTU = 1055J
1 BTU/h = 1055J/3600s = 1/3.41 W
125kBTU * 40% = 50kBTU
50kBTU/8 hours = 6.25kBTU/h * 1/3.41W/BTU/h = 1.83kW

1.83kW * 8h is 1.83E3J/s * 8h * 3600s/h * 1 BTU/1055 J = 50kBTU = 40% of the energy in 125kBTU, and
3.44kW * 8h is 3.44E3J/s * 8h * 3600s/h * 1 BTU/1055 J = 94kBTU = 75% of the energy in 125kBTU.

I went straight to J.   If we work it in BTUs first, we get:

118kBTU/tank * 1 tank/8h = 14.75kBTU/h * 1/3.41W/BTU/h = 4.32kW input power equivalent.

Efficiency = Continuous output power / 4.32kW
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