Chilling with a Wood Boiler

[Mushroom Man]

Not Chillin' (sitting back with a brewskie and watching the temperature rise in your boiler), but chilling.

I was uncertain whether this was a Boiler Room or Green Room topic.

I have a room in the barn that I'd like to turn into a giant fridge for storing mushrooms. The ongoing cost of chilling such a room with electricity or fossil fuels is daunting. (Electricity rates here have popped up 25% this year and there is no end in sight for the scaled increases. Our government is obsessed with giving away money to promote alternative electrical generation.)

I was wondering if the principles that apply to refrigeration and air conditioning could use very hot water (from storage) to do what electricity usually does in a fridge or AC to create the cooling effect. Clearly this is just for the warm months. Minimally heating the room in winter to prevent freezing is the cold month solution.

Has anyone tried to do this? Is it possible?

I intend to heat next season mostly with spent mushroom substrate, so the cost of fuel may be minimal, (it may be free; but I may also need some coal or wood to excite gasification...not certain yet as the substrate is still too high in moisture content to get a true picture of its gasification properties.)

 

[bigburner]

how big an area? What temp? What Humidity? Air circulation requirement ? -- the real short answer to your questions is it could be done but shouldn't. Can help with some pointers for direct expansion refrigeration. Insulation, compressor choices, etc.

 

[Fred61]

Google "ABSORPTION REFRIGERATION"

 

[Mushroom Man]

The size is 1600 cu ft. Humidity, (I had not thought about but) the environment should be as close to a conventional refrigerator as possible. No airflow or as little as possible.

It is clear to me that insulation should be superb to reduce operating cost. I had imagined something like a diesel-powered reefer but with the heat for the evaporator produced by hot water instead of fossil fuel.

 

[bigburner]

“ABSORPTION REFRIGERATION†would work. You would need to modify or custom build. but with a static evaporator [no fan] ceiling mounted with a "holding load" verse a "pull down load" The BTU requirement would be very low.

Don't think 180 water will get the job done with out some serious de rating.

FYI - refers are direct expansion. motor turning - open drive compressor. evaporator cold - condenser hot

do it on the cheap with a Window A/C unit - Google -- coolbot - then just build your own control. uses electric but it's cheap to do!

 

[Fred61]

I believe the medium is ammonia gas which boils at a pretty low temperature.

 

[benjamin]

Absorbtion chillers can easily operate with ridiculously low temperature water, at ridiculously low efficiencies, or as Bigburner put it "serious derating". They usually use ammonia dissolved in water, I think, but that's irrelevant, they're not the kind of thing you're going to design and build yourself, and I don't think they make something between the size of an RV fridge(propane/electric resistance) and truck size chillers for industrial use.

A semi trailer reefer unit is just a diesel engine driving a compressor refrigeration system. You could convert one to run on wood gas, but running it on diesel would be more expensive than electricity with my prices, plus a lot more hassle.

A geothermal heat pump may be a good example to start from if you're looking at building your own system. Your cool source could be well water, a ground loop or copper tube buried to form a direct condenser. You just need to round up a Copeland scroll compressor, either an expansion valve or capillary tube, the evaporator, and a bunch of tubing. Or stick with the slightly less efficient but much simpler window AC, or chop up the window AC and recombobulate it to your likeing.

 

[Hunderliggur]

I asked this question earlier this month for cooling https://www.hearth.com/econtent/index.php/forums/viewthread/67679/#774516 I actually desiged a solar fueled absorption chiller system in the 70's using a derated Arkla chiller and Daystar Solar Panels. It was expensive then and the technology has not improved much. This company http://www.solarpanelsplus.com/yazaki-solar-HVAC/ has some units. They like at least 180F water and you can see their BTU input requirements. Basically, you have to have your boiler running at the top end (>180F) but it can be done. You will need the best wood possible and a lot of BTU's probably. You may even want to consider chilled water storage to balance the boiler output to the loads. I would love to cool my house with wood!