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Thread: Re: rack power question
Re: rack power question
user name
 2008-03-26 06:37:58 

  


  

    I believe some of the calculations for hole/trench sizing per ton used for geothermal exchange heating/cooling applications rely on the seasonal nature of heating/cooling. ; 

I have heard that if you either heat or cool on a continuous permanent basis, year-round, then you need to allow for more hole or trench since the cold/heat doesn't have an off-season to equalize from the surrounding earth.


I don't have hard facts on hand, but it might be a factor worth verifying.

On Wed, Mar 26, 2008 at 2:23 AM, Petri Helenius < petrihelenius.fi">petrihelenius.fi> wrote:




Paul Vixie wrote:

&gt;

> aside from the corrosive nature of the salt and other minerals, there is an

> unbelievable maze of permits from various layers of government since there's

> a protected marshland as well as habitat restoration within a few miles.  i

> think it's safe to say that Sun Quentin could not be built under current

> rules.

&gt;


The ones I have are MDPE (Medium Density Polyethylene) and I haven't

understood that the plastic would have corrosive features. Obviously it

can come down to regulation depending on what you use as a cooling agent

but water is very effective if there is no fear of freezing (I use

ethanol for that reason). The whole system is closed circuit, I'm not

pumping water out of the ground but circulating the ethanol in the

vertical ground piping of approximately 360 meters. The amount of slurry

that came out of the hole was in order of 5-6 cubic meters. Cannot

remember exactly what the individual parts cost but the total investment

was less than $10k. (drilling, piping, circulation, air chiller, fluids,

etc.) for a system with somewhat over 4kW of cooling capacity. (I'm


limited by the airflow, not by the ground hole if the calculations prove

correct)




Pete







  

  
  
   
     
    

  

    Re: rack power question
  


  

     country flaguser name
Netherlands		
     2008-03-26 08:06:43
  


  

    
Dorn Hetzel wrote:
> I believe some of the calculations for hole/trench
sizing per ton used 
> for geothermal exchange heating/cooling applications
rely on the 
> seasonal nature of heating/cooling. 
>
> I have heard that if you either heat or cool on a
continuous permanent 
> basis, year-round, then you need to allow for more hole
or trench 
> since the cold/heat doesn't have an off-season to
equalize from the 
> surrounding earth.
>
> I don't have hard facts on hand, but it might be a
factor worth verifying.
That is definitely a factor. I do know that you can run such
systems 
24/7 for multiple months but whether the number is 3, 6 or 8
with the 
regular sizing I don't know. Obviously it also depends on
what's the 
target temperature for incoming air, if you shoot for
12-13'C the 
warming of the hole cannot be more than a few degrees but
for 17-20'C 
one would have double the margin to play with. It's also
(depending on 
your kWh cost) economically feasible to combine geothermal
pre-cooling 
with "traditional" chillers to take the outside
air first from 40'C to 
25'C and then chill it further more expensively. This also
works the 
other way around for us in the colder climates where you
actually need 
to heat up the inbound air. That way you'll also accelerate
the cooling 
of the hole.

I'm sure somebody on the list has the necessary math to work
out how 
many joules one can push into a hole for one degree
temperature rise.

Pete




  


  

    
  

  
  
   
     
    






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