bob g, trigen v 3.0

[mobile_bob]

name/location:
 bob g, tacoma washington usa

operational philosophy:
the design goal of this unit is for intermittent daily use, with an average run time of 2 hours per 24 hour
period. the unit will be but a single element in the power generation system for an offgrid home to be built in central kansas.

Bill of materials:
changfa S195idi (preban), st 7.5, one prestolite 110-555jho 12volt alternator, one leece neville  48volt nominal w/water cooled stator alternator,
sanden A/C compressor, custom built exhaust heat exchanger, 4 pass tube in tube coolant heat exchanger, amtrol 42 gallon indirect
fired hotwater tank with double wall exchanger, various other odds and ends

theory of operation:
the system operates on the hybrid design concept in that the unit will only run when there is sufficient need for both thermal
and electrical loads to be serviced. Down time power will be provided by a 48volt battery bank and inverter system, which will also
be supplied with power via solar and windpower.

my theory of operation is as follows, the trigenerator will not be allowed to run unless a series of factors are met. the unit will only
start when there is a need for recharging the batteries, recharging the thermal mass, reheat of domestic hot water, and refrigeration.

this will allow the unit to run at near 100% capacity which in testing has proven to be the most efficient mode of operation returning
the highest kwatt/hr/gr (electrical) and the largest delta T for the heat exchangers.  the heat from the exhaust, as well as cooling system will be
the primary focus, followed by the heat from the engine lube oil system  and that of the high output alternator stator as secondary
sources of heat.

the unit will produce a reliable 7kwatts electrical, so that with an average 2 hours per day there is the capacity of 14kwatt/hrs/day available

the objective of the unit is to not produce 100% of the electrical and thermal needs of the purpose built/highly insulated/and small by todays standard home, but rather for the unit to operate at its peak efficiency anytime it is called upon to operate.

the target overall efficiency of this unit is calculated at 77% overall efficiency, and there will be a need to work out a few more details in order to attain this level of efficiency, but i am convinced it is an attainable goal.

the unit will be fully contained in a small power room detached from the home, the excess radiant heat will be recovered by intermittent operation
and switching of the compressor from refrigeration duty to heat pump duty so that excess heat of operation can be recovered and transported safely to the living area. this heat recovery is not factored into the goal of 77%, but there is likely something on the order or another 5 percentage
points available.

in order for this unit to maximize its EPA rated overall efficiency the power and heat from the unit must be put to use, rather than dumped to
the outside environment via radiator, this limits the units viability for longer run times in the summer months because of the lack of use for heating btu's.

there is clearly a need for R&D into an absorption chiller to make use of the waste heat and extend the viability in warm and hot month for
air conditioning, but that is down the road for me at this time.

stage of development:
the unit has been assembled in prototype trim and under testing since november 2008, still need to install the coolant exchanger and the amtrol
tank so that more testing can be done. unit needs to be taken completely back apart, sandblast the chassis and powder coat, then make the final assembly.

name:
trigen 3.0

prior versions evolved on paper, the process made for v 3.0 to work as designed without surprises, at least so far.

more details and pictures to follow...

[mobile_bob]

just a thought before i get to much further into the process of reporting on the unit progress
i figured a preface might be in order

i am not asserting that my system is the "best" or "only" means of cogeneration, it might work out that it is not even
the best for my specific application. Clearly there are at least 4 different configurations that i can think of that cover the needs
of a very diverse set of conditions that might present themselves to folks living in different climates, different lifestyles, and differing
amounts of space and people living under the same system.

my system is simply one that i hope will work out to be efficient, clean and effective at providing for my needs in an integrated hybrid system.

fwiw, just wanted to get this out of the way early on.

bob g

[mobile_bob]

got back to work on the trigen over the weekend, and did some testing of the new water cooled 48volt alternator

so far the results are less than what i expected, but upon review the numbers are inline

the unit was able to sustain 57.6 volts at 100amps, but the efficiency is down to about 71%
as compared to the st 7.5 which is 78% efficient at a similar loading.

now if i were to use a smart charger and simply plug it into the st head, i might be able to get
a charger that is about 93% efficient, so

78% x 93% = 72.5% efficient

so it is about a wash, however

the watercooled stator is connected in wye instead of delta so that i can get the voltage i want at the rather low
drive rpm of 4650rpm.

the next step will be to go back into the alternator and reconnect it as delta, which will lower the stator resistance
and in doing so i would expect a marked increase in efficiency, but

i will have to change the drive ratio to something around 6000-6500rpm in order to get over 57.6 at full load.

alternatively if i find that the alternator cannot attain at least 81% efficiency i will revert back to the use of the 110-555jho
and drive both alternators, using them to charge the 48volt bank in a split charge regime, one alternator to charge one half
the bank, and the other to charge the other half of the bank. there are some advantages to doing this anyway.
the efficiency comes in at 80% with the 555's charging at 28.8volts and 100amps.

and the 555's don't seem to need water cooling of the stators to manage the task.

getting closer to what i would call the end of the tunnel on this aspect of the unit, after which it is time to move on to automation
and getting it ready to deploy.

bob g

[Henry W]

Thanks for posting this Bob, I am looking forward seeing which way works the best.

Henry

[mobile_bob]

made an executive decision today, the 48volt leece neville (water cooled stator) will go back on the shelf where
things are that will await a time when i have nothing better to do. 

it will need to be reconnected to delta, have the rectifier reinstalled, and be driven to above 6krpm, and then see where
it comes in on the efficiency scale, at this point the investment in time vs the possible gain in efficiency is not worth it
in my opinion,

i decided to go back to the use of the 110-555jho and use it to provide for 24volt nominal charging, and because the unit drives
two such alternators, i can split the 48volt bank and charge each half separately using the separate alternators. in testing the
alternators have proven to reach 80% efficiency which is more than acceptable for my needs.

using this method i can gain better control of the battery bank charging process anyway, which should work out to favor battery longevity.

over the weekend i will be resetting up the unit with dual controllers and splitting the 48volt bank to do some testing. i expect reasonably consistent
results.

for the 12volt excitation and starting battery charging source i will go with a switch mode power supply plugged into the st head which is running all the time anyway, it may as well cover those minimal loads while its spinning.

time is ticking away and i have just over 10 months before this thing has to be complete and ready to deploy, so i have to focus and get results
rather than continue testing subsystems trying to eek out another percent of efficiency.

bob g

[mobile_bob]

its been a long time since i was able to get anything substantive done on my project, pain management has
been quite poor and what little relief i get i spend trying to work to make a living... usually doesn't leave much
extra "feel good enough" to get much of anything done.

the dr. has stumbled onto a combination that seems to provide a bit more relief and i have been using the extra
time to get some things done, namely move stuff out of the shop. this leaves more room to actually work..

uncovered a rack mount unit and reworked it to accept 21" components, and loaded in 11kw worth of exeltech
inverter system, moved the 4 group 31 batteries to the lowest level of the rack system where they are close to the
inverters and provide needed ballast to make things more stable.

also loaded into the 19" end opening my controller rack component case, and changed out the sata drive bays for ide bays
now i can get started with assembling the individual controllers and slide them into the system for testing. these will make
for a nice winter project when it is too cold to work in the shop.

took  bit of time to start the wiring interfaces between the trigen and the rack system, and got the unit to autostart via a signal pulse, that is the first step of many to come.

at some point i still need to completely tear down the trigen and do the finish welding, sandblast it and either powder coat or paint
the darn thing. i must have well over 50 hours of heavy testing and the thing is still only tack welded together and sitting on steel saw horses and a single jack stand. it runs very smoothly but at around 1200lbs i really should stop and do the complete welding
of the frame system.

it runs even under full load smoothly enough that it could sit on 3 coke bottles without issue.

soon as i get things cleaned out a bit more, there will be pictures,

lots of pictures on the way

i got to get serious about finishing this unit, it will be installed and put into service by this time next year.

tick tock,, time is running out!

bob g