AC / refrigeration / absorption cycle questions

[Spaventa]

Hoping theres an engineer, repairer, manufacturer or designer of mobile refrigeration products...!

long shot but I think the absorption cycle may be the solution to a heat problem I have. Another source of heat may provide the solution in an rather paradoxical way... I have access to a heat source.. It produces lots of heat.
Its a metal surface that exceeds 500 c all the time. I could create a metal jacket around it with connection tails to use as a boiler for the cycle.

The rest of the parts of the cycle would give me free AC!!!

Help me spec this and build it and Ill test the theory if anyone with some knowledge can point the way :tippet:

To be honest anyone could use this method if they accumulate the heat they remove from their grow rooms. water cooling unit maybe???? maybe that system that exchanges heat from fans to water could do it better with refrigerant than water??? The heat you take away is used to cool the room further!? Seem to good to be true i must be missing something. law of diminishing returns made? fuck I'm stoned but I'm sure this has legs.

 

[queequeg152]

absorbtion chillers these days are pretty much only used where waste heat is present on an industrial scale. think steel mills that have a some sort of administrative building.

they used to build RV refrigeration systems that ran on waste engine heat... but were talking about friges here, less than 1000 btuh.

even if you could find a comapny building hardware suitably small, and assuming for a moment that you could afford the equipment... i doubt you actually have enough waste heat.

a typical heat pump system can reach a COP of around 5 pretty trivially. absorbtion systems are a small fraction of that typically... but again waste heat is free so efficiency means nothing.

absorbtion systems are not actually that hard to build tbh. Im not reccomending you try this... but your best bet probably would be having someone build you something.

again though you need to elaborate on your waste heat situation... again you need lots of heat and lots of heat exchanger... and something like a hot furnace wall is NOT going to be suitable.

 

[Spaventa]

absorbtion chillers these days are pretty much only used where waste heat is present on an industrial scale. think steel mills that have a some sort of administrative building.

they used to build RV refrigeration systems that ran on waste engine heat... but were talking about friges here, less than 1000 btuh.

even if you could find a comapny building hardware suitably small, and assuming for a moment that you could afford the equipment... i doubt you actually have enough waste heat.

a typical heat pump system can reach a COP of around 5 pretty trivially. absorbtion systems are a small fraction of that typically... but again waste heat is free so efficiency means nothing.

absorbtion systems are not actually that hard to build tbh. Im not reccomending you try this... but your best bet probably would be having someone build you something.

again though you need to elaborate on your waste heat situation... again you need lots of heat and lots of heat exchanger... and something like a hot furnace wall is NOT going to be suitable.

I can't elaborate too much at this stage because theres a bigger picture Im keeping under my hat. The heat source and heat exchange potential in my situation is huge.
I can harvest as much heat as I like and exchange at a rate that I could never exceed.
The limitation is on the equipment itself - much like if you had a source of free electric, its just a question of how much can you use. None of the gas freezers I see quote BTU figures. maybe because they are so low. this is only because they have a tiny heat source and almost no heat exchange! What would the cooling potential be with those same size components but with unlimited heat source and exchange? Speeding up the cycle?

 

[boo_baup]

How many tons of cooling do you need? Can you describe the heat source in more detail? I'd need to estimate the heat output (btu/hr) not just its surface temperature.

For example, you can get 5 tons of chilling (in the form of 44 F water at 12.1 GPM) out of 85.7 MBtu/hr (190 F water at 19 gpm). That will come in the form of a 24x30x69 (WxDxH) box that weighs just under 1000 pounds. It'll have supply/return flanges for the hot water input, the chilled water output, and the heat rejection circuit. It'll also consume about 48 watts of power.

These types of systems can scale much higher. I'm currently working on an industrial cannabis project that will use a 600 kW natural gas engine for power and take all of its waste heat (jacket water and exhaust gas) to power a double-effect 150 ton absorption chiller.

I've developed a number of industrial projects using waste heat driven absorption chillers and understand the engineering and economics pretty well.

 

[Spaventa]

How many tons of cooling do you need? Can you describe the heat source in more detail? I'd need to estimate the heat output (btu/hr) not just its surface temperature.

For example, you can get 5 tons of chilling (in the form of 44 F water at 12.1 GPM) out of 85.7 MBtu/hr (190 F water at 19 gpm). That will come in the form of a 24x30x69 (WxDxH) box that weighs just under 1000 pounds. It'll have supply/return flanges for the hot water input, the chilled water output, and the heat rejection circuit. It'll also consume about 48 watts of power.

These types of systems can scale much higher. I'm currently working on an industrial cannabis project that will use a 600 kW natural gas engine for power and take all of its waste heat (jacket water and exhaust gas) to power a double-effect 150 ton absorption chiller.

I've developed a number of industrial projects using waste heat driven absorption chillers and understand the engineering and economics pretty well.

Just seen this! wow you are who I need to talk to! Ill put together a better reply later today

 

[hazyfontazy]

like already said you need a lot of shit for this ,,my dad helped on a project many years ago ,,have a watch for idea of size you need to produce power

http://discoverthanetearth.co.uk/virtual-tour.php#virtual-tour-anchor

 

[Spaventa]

How many tons of cooling do you need? Can you describe the heat source in more detail? I'd need to estimate the heat output (btu/hr) not just its surface temperature.

For example, you can get 5 tons of chilling (in the form of 44 F water at 12.1 GPM) out of 85.7 MBtu/hr (190 F water at 19 gpm). That will come in the form of a 24x30x69 (WxDxH) box that weighs just under 1000 pounds. It'll have supply/return flanges for the hot water input, the chilled water output, and the heat rejection circuit. It'll also consume about 48 watts of power.

These types of systems can scale much higher. I'm currently working on an industrial cannabis project that will use a 600 kW natural gas engine for power and take all of its waste heat (jacket water and exhaust gas) to power a double-effect 150 ton absorption chiller.

I've developed a number of industrial projects using waste heat driven absorption chillers and understand the engineering and economics pretty well.

I want swimming pool heat exchangers for exhaust heat recovery - they are ideal and are tons more efficient than a water jacket.

How many BTUs of cold could I get off a car engine? is there a rough BTU/HP equation or rule of thumb? Im wondering if a car engines heat can run the AC and charge cooling. Freeing the engine of parasitic AC pumps and increasing the volumetric efficiency (way beyond atmospheric chargecooling/intercooling) of the engine for free? I also wondered about using one of those exchangers as a boiler for a steam turbine to drive the alternator. Comes down to how much heat my engine makes and how much of that the absorption cycle and a steam turbine can get out of it. It would be sweet if the alternator alone could be run off the exhaust heat via steam. That could mean its worth throwing out all the belts and pulleys on the front of the engine, put an electric motor on the water pump etc etc. I already have electric PAS.

Im convinced our family also generates enough rubbish to run a small incinerator/boiler/turbine and generate electric for the home.

 

[MrBungle]

This is an interesting topic, that I would certainly like to learn more about...

 

[boo_baup]

If you take a 215 HP diesel truck engine (MAN is the company) converted to run on natural gas and mate the output shaft to a 160 kW Newage generator (alternator), you'll get electricity at 32% electrical efficiency (LHV). Then you run the jacket water through a shell a tube heat exchanger (similar to what you posted but industrial) that collects the exhaust heat, you're left with 185 MBH in the form of 194 F hot water at 101 gpm. If you send that hot water to a Yazaki absorption chiller you'll get about 45 tons of chilling out of it.

Doing this for an actual car engine is problematic because the absorption chillers are heavy. The Yazaki unit I mentioned above is just under 6,000 pounds. Carrying that weight around would defeat the purpose. Using exhaust heat steam generator to run a turbine would likely be unfruitful as well. You'd generate a very small amount of power after introducing a ton of complexity. BMW experimented with this for a little while and abandoned the project.

 

[boo_baup]

Here's the solution that I believe actually makes sense for growing weed at an industrial scale.

Use a natural gas engine generator to make electricity at high efficiency. Send jacket water heat and exhaust heat separately to a double effect absorption chiller to provide your chilling. Then, run the engine's exhaust through an oxidation catalyst and a selective reduction catalyst to get its pollution levels well below OSHA standards. Now feed that CO2 to your plants.

Denver County just released a Cannabis Sustainability Best Practices Guide (linked below) that recommends exactly this process. Check out pages 22 and 23.

http://www.denvergov.org/content/da...st Practices Management Guide web - final.pdf

 

[Spaventa]

If you take a 215 HP diesel truck engine (MAN is the company) converted to run on natural gas and mate the output shaft to a 160 kW Newage generator (alternator), you'll get electricity at 32% electrical efficiency (LHV). Then you run the jacket water through a shell a tube heat exchanger (similar to what you posted but industrial) that collects the exhaust heat, you're left with 185 MBH in the form of 194 F hot water at 101 gpm. If you send that hot water to a Yazaki absorption chiller you'll get about 45 tons of chilling out of it.

Doing this for an actual car engine is problematic because the absorption chillers are heavy. The Yazaki unit I mentioned above is just under 6,000 pounds. Carrying that weight around would defeat the purpose. Using exhaust heat steam generator to run a turbine would likely be unfruitful as well. You'd generate a very small amount of power after introducing a ton of complexity. BMW experimented with this for a little while and abandoned the project.

your using the engine to run the alternator directly - I'm only looking at the waste exhaust heat. Those pool exchangers are available in all scales - domestic ones are suitable for my application but there are obviously industrial ones for large public pools. They are cast iron affairs that weigh like a boat anchor. they all use the same principle though - numerous smaller tubes exchange more heat to the water flowing around them.

I need to experiment with some parts really. I have an engine on a stand that I can set up in a test configuration with some fairly inexpensive parts for the car steam driven alternator idea. The home refuse/turbine/generator side is cheap as is the boiler in theory (a modified gas cylinder will do) the exchangers I have in mind aren't much but Stean turbines are a hurdle. They are either pocket size brass curiosities for children to marvel at or zillion pound things the size of a football pitch that powers a countries grid. Not a lot in between. Ive ordered an impeller I think is right based on some research and Im getting the housing and spindle machined up by a local chap (if he hasn't died of old age since I saw him last) Im going for an radial impulse design (watermill basically). I looked the Tesla thing but its complicated and you'd have to trust the "experts" on the net for instructions to build one. there a reason no one, not even tesla proved its as good as he claims. The ones on youtube made out of stepper motors look like they couldn't pull the skin off a rice pudding.