Quote from: mwizard on September 11, 2014, 01:44:55 AM

Quote from: ltorsini on September 11, 2014, 12:22:46 AM

**Thanks for the feedback - its good stuff... except for #4. We're talking about a minimum temperature difference today of > 100f to ambient which is more than enough to run a single or double effect absorber. Remember, this thing is running at 180 to 200f right now (with off the shelf parts!), that's more than enough TD to regenerate desiccant or run an absorber. The ideal range for the absorptive refrigerator is 180 - 200f, if you go above 230f it actually looses efficiency and starts to break down the refrigerant. The plan is start building chips that hit 210 to 250f.

http://web.stanford.edu/group/narratives/classes/08-09/CEE215/ReferenceLibrary/Chillers/AbsorptionChillerGuideline.pdf
http://www.yazakienergy.com/waterfired.htm

No one is saying that absorption refrigeration is not possible. When I was very young my parents lived off the electrical grid. We had an old kerosene powered refrigerator which ran by burning kerosene. It used absorptive refrigeration. The refrigerator was replaced as soon as the far cheaper electricity became available.

We are just saying it is extremely unlikely to be economic running off bitcoin miners.

With your proposed temperature difference of 50C or even 100F the efficiency will be 5 to 10%. The second law of thermodynamics sets an absolute limit to any heat engine.

Lets be really totally optimistic and assume you are aiming for a 10% efficiency. If you output 1,000W of heat from a miner you will get at the most 100W or useful work out and still have to get rid of at least 900 Watts of heat. I just cannot see it even coming close to making economic sense.

Your web site says you have a "Lead Scientist" so I assume there has been some calculations done on expected energy output, on the overall economics, and on waste heat removal to maintain the 100f difference in temperature.

To repeat. It is the efficiency and economics we question. Not whether absorption refrigeration exists.

Ahhh... now I understand. We are talking about 2 seperate issues. First, we have no intentions of running any of this off of a bitcoin miner. Were talking about running it off of about 20kW in the appliance. It seems the biggest hangup might be scale, not science.

Secondly, the 'rube goldberg' device pictured above is about 75% efficient at transferring heat to the loop at low temps and it drops to about 50-60% at higher temps above ~160. The second prototype is submerged in a silicon fluid and well insulated, Sri (senior scientist) is modeling the device now in Comsol http://www.comsol.com/comsol-multiphysics?gclid=CNnmyLeI2MACFSsV7AodCTsALQ and its looking like we'll easily break into the mid 90% efficiency for heat capture with the device when submerged.

As for the economics - free energy for computation isn't going to be economic? Remember we are using energy once and getting two benefits - heat and computation. You pay for the heat, the computation is free (from an energy perspective) except for the cost of the device.

Thanks-