residential absorption coolers

[ivymike]

okay, since natural gas prices are fixin' to get real low in the USA, I've been pondering ways to make a bit of money from the availability of abundant inexpensive energy. First thing that comes to mind is to find ways to displace the use of expensive energy. Since converting automobiles involves certification from the EPA and the fueling infrastructure is sparse in Houston, I'm looking at other big users of energy...and the first thing that comes to mind is air conditioning.

I have looked online for a vendor of ammonia absorption a/c units sized appropriately for home use, and have come up blank so far. Seems like they should be a shoe-in with inexpensive gas, especially in a hot climate like Houston. What gives? Why aren't there combined gas/solar (solar to pre-heat the boiler) units on the shelf at the Home Depot, or available from my local AC guy? Looks like there are at least a couple of companies making units for use in RVs.

 

[TheTick]

Watch Mosquito Coast lately?

Check out the RV market. My camp trailer has an absorption fridge.

Perhaps an air-conditioning co-op, get several adjoining residences to share a larger unit? Don't forget apartments.

 

[ivymike]

yeah, the apartments seem an obvious opportunity. A/C co-op might be do-able in a new community development.

found one vendor, finally:

http://www.apexaircon.com/absorption-chillers.php

 

[ivymike]

another option might be to convert conventional AC units to run from the flywheel of a recip engine... but that gets back into EPA territory pretty easily.

 

[ivymike]

on the latter... take a home like mine w/about 6 tons of total A/C capacity (nevermind that it's split between a pair of units)... say I have an 11-SEER unit, that means I'm using about 2kWe to drive the A/C when it's running.

When I look at gas prices in houston, $0.54385/CCF presently, which is about 105506 kJ. If my gas engine was 25% efficient, I could get about 26376 kJ of work for $0.54385, which is about 48500 kJ/$ or about 13.47kWh/$ ($0.074/kWh)...
I currently pay $0.086/kWh for my electricity, so nevermind that one, for now. If gas prices drop over the next year or two to 1/3 of their present price, then electricity will probably fall too... seems like a game I wouldn't win.

 

[zdas04]

It is a tough game to play. People that bet on wellhead prices staying over $9/MCF are mostly out of business today. People that bet in 2000 that gas prices would never get over $2/MCF are also hurting after the 2003-2008 build-up.

At today's price, drilling rigs are moving out of gas fields as fast as they can get out of contract commitments. Production companies are refusing to pay overtime to start compressors at night and on the weekends.

If you drop Shale Gas out of the mix, supply is significantly down between 2008 and 2011. With the Shale Gas feeding frenzy (and some Shale lease agreements that were kind of dumb) net gas is still increasing, but at a slower rate than pre-2012.

The day someone gets a permit to build an LNG and/or GTL facility we'll start to see upward pressure on prices. Once the new uses are on line, prices will increase dramatically and everyone who made permanent conversions from coal/oil to natural gas will be disadvantaged relative to competitors who "stuck with the one what brung them".

Day trading on facilities that take 10 years to permit and build is a really good way to go broke.

David

 

[Compositepro]

I've long wondered how absorption chiller efficiency compared to compression chillers but never found any good answers. Your question prompted me to research a little more and I found this publication that has some useful data:

http://www.stanford.edu/group/narra...brary/Chillers/AbsorptionChillerGuideline.pdf

A major factor in the comparison is the fact that only 27% of the heat energy in fuel is delivered as electrical energy to the end user (see page 5). The paper uses COP (coefficient of performance) which runs around 1.0 for absorption and 6 for compression. I need to look into how this is different from SEER.

 

[waross]

I did some investigation for a client years ago on absorption cooling. I found that ammonia was not the only gas that was usable. My client owned a lobster processing and freezing plant. He was also the largest share holder of a small diesel generating utility, located right next door. During the heat of the day, we had the heat rejection from about one mega-Watt of diesel generation.
I found out a lot of interesting stuff, but no hard answers or prices. I came to suspect that maintenance costs for larger plants were quite high.
I have always wondered how far or how large the RV model could be expanded. Be aware that there is a pad of hydrogen gas over the ammonia in an RV refrigerator and the resulting partial pressures are the trick that lets them operate on convection only, without pressure boosting pumps between the evaporator side and the condensing side.


Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Eltron]

My guess is that there is just too much fluctuation with gas prices. If you look at a chart of gas prices over time and compare that to a chart of coal prices over time they will look very different. If the gas prices could be stabilized at the rate that they are now then the absorption chillers for residential use would most likely be a viable alternative. However, I don't think anybody is going to put skin in the game to develop, market, and sell an expensive consumer product that hinges on gas price speculation. Now, if something could be designed to switch from gas to electric depending upon current prices then you might have something.

Dan

http://www.eltronresearch.com

Dan's Blog

 

[waross]

Does anyone have credible figures comparing energy consumption between Compressor cooling and absorption cooling??
Something simple:
I want to run a ton of refrigeration for 24 hours. How many KWHrs to use a compressor system and how many KWHrs to use an absorption system?
The link provided by compositepro seems to be agenda driven.
"A major factor in the comparison is the fact that only 27% of the heat energy in fuel is delivered as electrical energy to the end user "
They spend a lot of time on savings due to avoiding peak demand charges and similar issues but seem to avoid every opertunity to provide a direct comparison.
BUT consider. Cold water absorbs ammonia. Hot water rejects ammonia.
A quantity of water must be heated to drive off the ammonia and then cooled to be ready to absorb more ammonia.
At first glance, heating and cooling water seems to be an energy intensive way to compress ammonia.
I suspect that absorption is best used where heat energy is very cheap or a waste product.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[TheTick]

The efficiency of the cooling machine isn't nearly as important as the effectiveness of the sales machine.

 

[ivymike]

Heat is easy to find in Houston... could use ambient to get to 90F, a black piece of metal to get to 150F (?) and a little bit of flame to get the rest of the way there. If I had a bunch of diesel exhaust to play with, that'd be a free source of energy.

 

[ScottyUK]

We have a massive surplus of low grade LP steam at our site. We looked at using an absorbtion chiller to provide chilled water for the HVAC plant in futile bid to avoid building a new substation by divesting heating and cooling loads onto other energy sources such as steam and fuel gas.

The word from York was that (their) absorbtion chillers are best suited to large baseload cooling applications and wouldn't be happy running in a cyclic mode for our type of application. I don't know if small units have similar problems with cyclic loads, but there's always forum403 to ask the question if you're serious.


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If we learn from our mistakes I'm getting a great education!