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Author Topic: In and RE http://www.microcogen.info/index.php?topic=1047.0;topicseen  (Read 83161 times)
Lloyd
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« on: June 18, 2010, 08:08:50 AM »

http://www.microcogen.info/index.php?topic=1047.0;topicseen

Since I haven't joined SOMRAD yet...dont even know if I will be accepted/excepted. I had a thought/question to Westcliffe01's response http://www.microcogen.info/index.php?topic=1047.msg12673#msg12673

Westcliffe, I agree with about 99% of your post...my question is? isn't your calculation a wild duck in re btu calcs based on burning wood? Wood tends to over heat, It seems that a better/more accurate HEAT DEMAND would be to do a proper heat loss calc for the proposed building being heated.

Also just a thought...it seems to me that using reverse refrigeration heat pump tied to the heat sink(hot water storage tank) would lead to a more efficient heat transfer to the house. Then you would have a deeper discharge of the heat storage resulting in a wider temp difference on the heat exchanger side, also increasing efficiency there.

Would an engine driven compressor help drive the system, act as additional load to make sure the prime mover is always loaded at it best efficiency. IE...in a battery system...the compressor could add load when the charge cycle is in absorption/float...or when more heat is needed then electricity. Or to make it simple using the Masterflux Rolling Piston, and individual unit for each zone in the House much like the systems installed on  Large Boats, the are DC driven PM units. They are also capable of working in reverse and providing Air-condition to that zone.

I'll look for my answer in the original topic.

Thanks Lloyd
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JUST REMEMBER..it doesn't matter what came first, as long as you got chickens & eggs.
Semantics is for sitting around the fire drinking stumpblaster, as long as noone is belligerent.
The Devil is in the details, ignore the details, and you create the Devil's playground.
Crumpite
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« Reply #1 on: June 18, 2010, 09:10:47 AM »

Lloyd,

I don't know about the other folks, but I know nothing about boat systems except what I've learned from you.
It seems that there's a lot to be learned from the technology, but I can't seem to find any condensed source on how power/heating systems on boat work.

Do you have any sources that us old farm boys can learn from ?

Please do keep the ideas coming !
Crumpite


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Lloyd
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« Reply #2 on: June 18, 2010, 10:05:51 AM »

Lloyd,

I don't know about the other folks, but I know nothing about boat systems except what I've learned from you.
It seems that there's a lot to be learned from the technology, but I can't seem to find any condensed source on how power/heating systems on boat work.

Do you have any sources that us old farm boys can learn from ?

Please do keep the ideas coming !
Crumpite




Here's a start to get an idea of what parts are available http://www.suremarine.com/manuals/webasto-sales-literature/general-heating-catalog.pdf

And here is a link to a Marine AIR design http://www.dometic.com/enus/Americas/USA/Marine/Cruisair/ There are also other makes, but using the system design and modifying to our application should give everyone a good start.

And here is a the rolling piston from Masterflux http://www.masterflux.com/


http://www.masterflux.com/userimages/RG.MPG
this is a nice little video on the rolling piston design
Lloyd
« Last Edit: June 18, 2010, 10:30:30 AM by Lloyd » Logged

JUST REMEMBER..it doesn't matter what came first, as long as you got chickens & eggs.
Semantics is for sitting around the fire drinking stumpblaster, as long as noone is belligerent.
The Devil is in the details, ignore the details, and you create the Devil's playground.
Westcliffe01
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« Reply #3 on: June 19, 2010, 08:02:49 AM »

Lloyd, you are absolutely correct that using a heat pump will greatly increase options regarding heat storage and extraction.   The only reason why I made no comment in this regard is that I have not done much investigation, and hence do not know how much electrical power would be needed to run the heat pump for 24 hours/day.

Theoretically, provided one had sufficient insulated liquid storage, one could use solar collectors to charge several thousand gallons of fluid during summer and then extract this heat all winter using the heat pump.    A second fluid storage containing several thousand more gallons of brine could be chilled through a heat exchanger and circulation pump in winter, and this used with the same heat pump to provide cooling in summer time.

It can easily be seen that the major operating cost with a Cogen system is fuel.   In my case, provision of the requisite amount of electricity would not provide nearly enough heat to cope with typical midwest heat demand.   Provision of additional electricity to run a heat pump 24/7 through additional run hours on the generator may increase my variable cost substantially.   For those with access to "cheap" utility power, the heat pump could be a very efficient option based on the scheme above.

It has been a long time since I did any refrigeration calculations (80's), but perhaps I should investigate the power requirement for transferring 25kbtu/hour from a fluid source at 50-130F to  radiant heating exchangers expecting 90F input.  Obviously at 130F at source one would be using a tempering valve and once one approaches 90F it would transition to running the heat pump.  As the source temperature drops, the power demand would progressively increase.  I just have no idea of ballpark numbers right now.
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Will need 10-15kW for running metal working shop.  Much less (3-5kW) for residence.  Cabin location is at 8000ft altitude in the Rockies, so a turbo will likely be needed for best efficiency. No need for air conditioning...
mobile_bob
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« Reply #4 on: June 19, 2010, 08:49:24 AM »

for more interesting reading on thermal storage, iirc MIT house built back in the 30s or 40's
used something on the order of 27k gallons of water buried in a tank under the house, the water was solar
heated in the summer and would provide most if not all the needed heat over the new hampshire winters.

again, from memory

the house worked very well for many years until the tank rusted out and started to leak away the water.

bob g

did a little digging, it was 1939 and was known as MIT solar one house, google brings up lots of info about it.
« Last Edit: June 19, 2010, 08:57:15 AM by mobile_bob » Logged
Lloyd
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« Reply #5 on: June 20, 2010, 01:32:21 PM »

Mobile-Bob has addressed this issue at least a couple of times.

Starting with our use of energy in the house...I like his idea of batching chores that are energy consuming around the run times of the generator...this is a valid way to make sure the system is fully loaded, and operating at it's peak efficiency.

Also dwelling design can play a huge roll in our energy consumption, both spacial design, and mechanical design.

In the early 80's I was involved in a partnership that developed a small housing development 18 homes total, all were passive solar, and bermed on the North, West and east sides. The lots were layed out on the Solar axes, which was not due south for the the lat/long.

The homes were all super insulated, and by design the main living areas were in the core of the house, with only one wall adjoining the exterior, that being the south/solar wall this wall had a a Solarium that separated the heated wall from the outside temps. The East/West/North walls all had bedrooms, laundry, baths and closets buffering the main living space from the exterior walls. This created zones for the heating system, so that the main space heat loads were light, due to the buffering, and the bed room spaces only maintained low heat, when they weren't occupied.

The heating system, was a gas fired boiler/hydronic zoned heat. We chose that over heat pumps 1. bc air conditioning wasn't mandatory, and 2. It's very hard to zone a single unit heat pump system. Our cooling was achieved by the Solarium creating a solar chimney drawing cooler air through the house from the shade side of the home.

These homes consumed a third of the gas and electricity of similar sized homes, in adjoining neighbor hoods. We built them on spec, and all were sold before the construction finished...This at a time when the economy was coming out of 21% prime rate..and houses in the direct area were average time on the market of 90-150 days.

Now with some smart planning a Micro Co-Gen...I think could provide an economical energy source that competes with grid power costs. I like the Master Flux reversing Heat pumps bc 1. They can be sized to max efficiency of each zone.  2. They are variable power so instead of drawing full power all the time when the load is light, they automatically scale themselves. 3. They can convert our excess heat @ 3 or 4 to one over a typical hydronic heat exchanger heating system.

Lloyd
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JUST REMEMBER..it doesn't matter what came first, as long as you got chickens & eggs.
Semantics is for sitting around the fire drinking stumpblaster, as long as noone is belligerent.
The Devil is in the details, ignore the details, and you create the Devil's playground.
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