[Bldg-sim] [BLDG-SIM] earth-air exchanger (earth channels)

Neeraj Kapoor near_ej at yahoo.com
Mon Jun 23 03:48:15 PDT 2008


Thanks Brian,

Looking up on the internet I came across a link that summarizes one Dr.

Didier Thevenard's (of Numerical Logics Inc.) search carried out online

and compiled together regarding this subject -- 
http://www.emr.gov.yk.ca/energy/pdf/biblio_search_earth_tubes_v3_1.pdf 
-- It might be useful for folks who may want to propose / model 
earth-air tunnel heat exchange (EATHE) systems.
I am taking the liberty of posting the relevant part of your reply 
(below) as well, for the benefit of  everyone on this list.

sincerely,
Neeraj

Brian Fountain wrote:
> I too am just starting a project proposing the use of Earth Tubes.  
> Currently I am modeling in eQUEST as well and have not found a good 
> way to model this system.
>
> I did run across the following article:  
> http://gundog.lbl.gov/dirpubs/SB06/kwangho.pdf
> which describes an earth tube algorithm implemented in EnergyPlus. 
It 
> also describes parametric runs for 4 parameters (depth, diameter, 
> velocity and length).  As yet, I have not tried this as I . . . 
> /[omitted text]./
>
> Good luck!
>
> Brian
>
> Neeraj Kapoor wrote:
>> Hello everyone,
>>
>> I am trying to model Earth-Air tunnels in eQUEST located in a 
>> tropical,composite climate (New Delhi). Following the last two 
>> threads on this issue dated Nov. 2003 and Oct, 2006 (shown below) 
>> nothing else seems to have been discussed, especially relating to 
>> modeling this strategy in eQUEST? If anyone has had any experience 
>> with it then please share. I'd appreciate your feedback. Meanwhile, 
>> let me try and explain the system that I am trying to model and how
I 
>> am approaching it --
>>
>> Earth-air (horizontal) tunnels utilize 100% outside air as it is 
>> blown through them. This brings down the temperature as the air is 
>> sensibly pre-cooled for the air handling unit. In the hot-dry months

>> the air is either delivered or is subjected to direct-indirect 
>> evap-cooling. For warm-humid periods a small portion of the 
>> pre-cooled air stream is subjected to DX coil where it drops most of

>> its moisture and is mixed with the rest of the air stream In 
>> principle my strategy will be to model ground-source heat exchanger 
>> (GSHX) wherein a fluid (water) rejects or gains heat and transfers 
>> the benefit to the air handling unit using 100% OA. I am guessing 
>> that the transfer of heat between water-earth via the GSHX and then 
>> water-air in the AHU has to be very efficient to diminish losses 
>> incurred and model this system fairly accurately. I will finally 
>> subtract the pumping energy from the total. Here is the crux, and
the 
>> questions --
>>
>>    1. Am I thinking in the right direction?
>>    2. How does one increase the efficiency of the GSHX process to
best
>>       reflect earth-air heat exchange? The aim as I said earlier is
to
>>       diminish the losses incurred due to the water-earth and
>>       water-air processes of the GSHX?
>>
>> For now, I am tied to eQUEST to solve this problem because a large 
>> time-consuming part of the model is already accomplished. However if

>> there is a better way to address this with any other tool then
please 
>> do not shy from sharing your knowledge. Many thanks for helping in 
>> the past and in advance on this one.
>>
>> sincerely,
>> Neeraj
>>
>> Neeraj Kapoor
>> t: +91-99581.70018
>> Kalpakrit Sustainable Environments Pvt. Ltd.
>> New Delhi
>>
>> ---------------
>> Victor Hanby wrote:
>>  
>>> >
>>> > On 31 Oct 2006, at 10:07, Yatin Choudhary wrote:
>>> >
>>>  
>>>> >>
>>>> >> hi every one
>>>> >> i am trying to simulate a type 56 with earth air tunnel
hypocast
>>>>     
>> ,...  
>>>> >> want
>>>> >> to compare with a 1.5 TR window unit ac
>>>> >> please advise
>>>> >>
>>>> >>
>>>> >> ======================================================
>>>> >> You received this e-mail because you are subscribed
>>>> >> to the BLDG-SIM at GARD.COM mailing list.  To unsubscribe
>>>> >> from this mailing list send a blank message to
>>>> >> BLDG-SIM-UNSUBSCRIBE at GARD.COM
>>>> >>
>>>>     
>>> >
>>> > Dr Farraj Al-Ajmi pretty much did this for his PhD studies at > 
>>> Loughborough University (UK). It's described in
>>> >
>>> > Al-Ajmi, F., D.L.Loveday and V.I.Hanby 2006 ``The cooling
potential
>>>   
>> of  
>>> > earth-air heat exchangers for domestic buildings in a desert
>>>   
>> climate''  
>>> > Building and Environment 41:235--244.
>>> >
>>> > and
>>> >
>>> > Hanby, V.I., F.Al-Ajmi and D.L.Loveday 2004 ``The optimal design
for
>>>   
>> a  
>>> > ground cooling tube in a hot, arid climate''  Building Services >

>>> Engineering Research and Technology 26(1):1--10.
>>> >
>>> > Farraj wrote TYPES for the ground cooling tube and the subsoil > 
>>> environment. I've lost touch with him but I think he has posted
here 
>>> > in the past. He might be able to help you with some code. I 
>>> modeled > the ac unit sing a fixed temperature approach for each 
>>> coil > (evaporator and condenser) then assumed a fixed fraction of 
>>> Carnot to
>>>   
>>
>>  
>>> > get the energy consumption.
>>> >
>>> > Vic Hanby
>>> >
>>> > -----------------------------------------------
>>> > Professor V I Hanby
>>> > Institute of Energy and Sustainable Development
>>> > De Montfort University
>>> > The Gateway
>>> > Leicester LE1 9BH
>>> > UK
>>> > ------------------------------------------------
>>> >
>>> >
>>> > ======================================================
>>> > You received this e-mail because you are subscribed to the > 
>>> BLDG-SIM at GARD.COM mailing list.  To unsubscribe from this mailing
>>>   
>> list  
>>> > send a blank message to BLDG-SIM-UNSUBSCRIBE at GARD.COM
>>>   
>>
>>     * /To/: <BLDG-SIM at xxxxxxxx <mailto:BLDG-SIM at DOMAIN.HIDDEN>>
>>     * /Subject/: [BLDG-SIM] earth-air exchanger (earth channels)
>>     * /From/: Denis Bourgeois <denis.bourgeois at xxxxxxxxxxxxx
>>       <mailto:denis.bourgeois at DOMAIN.HIDDEN>>
>>     * /Date/: Fri, 21 Nov 2003 15:27:36 -0500
>>     * /List-unsubscribe/: <mailto:BLDG-SIM-Unsubscribe at gard.com>
>>     * /References/:
>>       <MDAEMON-F200311201548.AA4849171pd80000629044 at xxxxxxxx
>>      
>> <mailto:MDAEMON-F200311201548.AA4849171pd80000629044 at DOMAIN.HIDDEN>>
>>       <MDAEMON-F200311211204.AA0424687pd80000630311 at xxxxxxxx
>>      
>> <mailto:MDAEMON-F200311211204.AA0424687pd80000630311 at DOMAIN.HIDDEN>>
>>     * /Reply-to/: denis.bourgeois at xxxxxxxxxxxxx
>>       <mailto:denis.bourgeois at DOMAIN.HIDDEN>
>>     * /Sender/: postman at xxxxxxxx <mailto:postman at DOMAIN.HIDDEN>
>>
>>
------------------------------------------------------------------------
>> Bonjour Hugues,
>>  
>> I'm unaware of any single program that automatically sets this up. A

>> very discrete finite-... 3D conduction model would be desirable, but

>> depending on your specific needs, ESP-r would be a very good 
>> candidate as an annual assessment tool. I've used ESP-r for 
>> underground air culvert assessment in the past and a couple of 
>> graduate students have used ESP-r for similar studies (Y. Jeong, a 
>> grad student at Concordia, and another student in Norway (a PhD 
>> student I believe) have both used ESP-r for assessing the Media 
>> School in Norway, which has an
>> underground air culvert).
>>  
>> In Jeong's case, the culvert is modeled as one zone, but it is
fairly 
>> straightfoward in ESP-r to subdivide this in, let's say, 10 zones
>> (e.g., a 40m culvert could be made up of ten 4m segments) - that's 
>> what I do. This will give you a more detailed assessment, e.g., of 
>> culvert surface
>>
>> temperatures along the airflow path (useful for condensation
assessment
>>
>> or to see just how effective the first segments of the culvert are
in 
>> relation to the last ones). ESP-r also allows you to set up an 
>> airflow network, but 'scheduled' airflows might be OK for your
needs.
>>  
>> The main challenge is setting up the surface boundary conditions. 
>> Without setting up a 3D conduction model in ESP-r (available, but
not 
>> for the faint-hearted), you'll have to specify boundary conditions 
>> for each surface. If the culvert is deep enough,
>> you can just feed it monthly ground profiles for ~¾ of the surfaces,

>> with harmonics calculated with standard models (see Maitos and 
>> Argiriou) - the same models used for ground-coupled heat pump 
>> simulation. If it's deep enough, the daily variations will be minor 
>> (~ ±1°C during the course of a month). The remaining ~¼ of the 
>> surfaces will more likely feel the effect of the nearby ground 
>> surface, so ambient air might be more suitable as a surface boundary

>> condition. If the culvert is very close to the ground surface, then 
>> it's a bit more tricky - maybe ~½ of the surfaces need ambient air
as 
>> a boundary condition. You can of
>> course 'tweak' the model to see just how sensible it is to variable 
>> changes.
>>  
>> Another point is setting up the right surface element
'constructions'
>> so on one hand it remains numerically stable, and on the other the 
>> constructions remain 'thick' enough so that using monthly profiles 
>> remains valid (at least conceptually).
>>  
>> Transsolar have modeled culverts for other energy consultants in the

>> past - maybe they've set up some basic modeling approach in TRNSYS
(?).
>>
>> Simpler empirical approaches are available: Argiriou and Maitos give
an
>>
>> overview of existing models found in the literature.
>>  
>> Good luck,
>>  
>> ----
>>  
>> Some references:
>>
>> Jeong, Y., and Haghighat, F. (2002) "Modeling of a hybrid ventilated

>> building, Grong School" /Proceedings of the 4th International Forum 
>> on Hybrid Ventilation: An Integrated Solution for Ventilation,
Health 
>> and Energy/, Montreal pp.198-207.
>>
>> Maitos, A. (1999) "Cooling with underground air ducts" MSc Thesis. 
>> University of Strathclyde: Glasgow. 68p.
>>
>> Argiriou, A.A. (1996) "Ground cooling" in /Passive Cooling of 
>> Buildings/. M.J. Santamouris and D.N. Asimakopoulos, eds., James & 
>> James: London. pp.360-403.
>>
>> Kumar, R., Ramesh, S., and Kaushik, S.C. (2003) "Performance
evaluation
>>
>> and energy conservation potential of earth-air-tunnel system coupled

>> with non-air-conditioned building" /Building and Environment/ 38
>> pp.807-813.
>>
>> Lay, R.M. (2003) "Earth Rangers Wildlife Centre - case study of
>> concrete use for energy efficiency" /Proceedings of the 8th 
>> Environmental and Sustainable Engineering Specialty Conference of
the 
>> Canadian Society
>> for Civil Engineering/, Moncton.
>>
>> Sawhney, R.L., Buddhi, D., and Thanu, N.M. (1999) "An experimental
>> study of summer performance of a recirculation type underground 
>> airpipe air conditioning system" /Building and Environment/ 34(2) 
>> pp.189-196.
>>
>> ----
>>
>> Denis Bourgeois
>> PhD student/doctorant
>> École d'architecture, Université Laval
>> denis.bourgeois at xxxxxxxxxxxxx <mailto:denis.bourgeois at xxxxxxxxxxxxx>
>>  
>> ----
>>
>>     ----- Original Message -----
>>     *From:* Hugues Boivin <mailto:huguesboivin at xxxxxxxxxxxx>
>>     *To:* BLDG-SIM at xxxxxxxx <mailto:BLDG-SIM at xxxxxxxx>
>>     *Sent:* Friday, November 21, 2003 1:11 PM
>>     *Subject:* [BLDG-SIM] earth-air exchanger (earth channels)
>>
>>     Does anyone knows a simulation tool to evaluate energy savings
by
>>     earth-to-air exchanger (earth channels) ?
>>          Thank you.
>>                    Hugues Boivin
>>     Mechanical Engineer
>>     Laval University
>>     GRAP (Groupe de recherche en ambiance physique)
>>
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