I have a 3 bed house that gets very hot in summer and it's been suggested an "earth pipe" may be a solution.
How much cooling effet can one expect from an "earth pipe"?
What diameter pipe is suitable? How long does the pipe run need to be? How deep does it need to be buried?
Are there any websites with further info I can go look at?
sponix
Try this:
In Germany they spiral a 8-12" pipe around a house foundations. Easy to do when building. Pretty common there.
Run the air thru a heat exchagnger in the house to avoid this.
NT
May as well bury hundreds of feet of plastic pipe underground and fill this loop with water. Use this to run though a water to air duct mounted heat exchanger. Will be easier to bury the small bore plastic pipe rather than large 8 to 12 inch plastic soil pipes.
Good idea, until crippled with actual numbers :-)
NREL says an average July day is 76.7 F in Phila, with w = 0.0133 and a 67.2 daily min and a 64.9 F dew point and a 54.3 F deep ground temp. A 5K Btu/h "earth air conditioner" with 80 F indoor air might look like this, viewed in fixed font:
1/G 1/800 54.3 F ---www---www--- 80 F
Oops. That's 565x0.539 = 304' of pipe, eg 1 $40 400' roll in a 100' trench.
The fan only needs to raise the air velocity from 0.05 to 0.095 m/s, ie
9.8 to 18.7 feet per minute. About 10% of the population finds 36 fpm at 80 F an annoying draft, and 160 fpm can blow loose papers off desks.Nick
20 MET=1.1'metabolic rate (met) 30 WME=0'external work (met) 40 DATA 80,0.0120,0.05,0.5 50 DATA 80,0.0133,0.095,0.5 60 FOR CASE = 1 TO 2 70 READ TC,WA,VEL,CLO 80 TA=(TC-32)/1.8'air temp (C) 90 TR=TA'mean radiant temp (C) 100 PA=29.921*3377.2/(1+.62198/WA)'water vapor ressure (Pa) 110 DEF FNPS(T)=EXP(16.6536-4030.183/(TA+235))'sat vapor pressure, kPa 120 ICL=.155*CLO'clothing resistance (m^2K/W) 130 M=MET*58.15'metabolic rate (W/m^2) 140 W=WME*58.15'external work in (W/m^2) 150 MW=M-W'internal heat production 160 IF ICLHCN THEN HC=HCF ELSE HC=HCN 290 XN=(P5+P4*HC-P2*XF^4)/(100+P3*HC) 300 IF ABS(XN-XF)>EPS GOTO 260 310 TCL=100*XN-273'clothing surface temp (C) 320 HL1=.00305*(5733-6.99*MW-PA)'heat loss diff through skin 330 IF MW>58.15 THEN HL2=.42*(MW-58.15) ELSE HL2=0'heat loss by sweating 340 HL3=.000017*M*(5867-PA)'latent respiration heat loss 350 HL4=.0014*M*(34-TA)'dry respiration heat loss 360 HL5=3.96*FCL*(XN^4-(TRA/100)^4)'heat loss by radiation 370 HL6=FCL*HC*(TCL-TA)'heat loss by convection 380 TS=.303*EXP(-.036*M)+.028'thermal sensation transfer coefficient 390 PMV=TS*(MW-HL1-HL2-HL3-HL4-HL5-HL6)'predicted mean vote 400 PRINT TC,WA,VEL,CLO,PMV 410 NEXT CASET (F) Wa Vel Clo PMV
80 .012 .05 .5 .5225705 80 .0133 .095 .5 .5225394Innova AirTech Instruments has an excellent comfort web site...
Kelvin Line Source Theory
Norton Equivalent Circuit
rather than
air-water
(80-54.3)/(1/G+1/800)
Btu/h-F of
ln(1/(0.722/12)/(2Pi0.65)
2weeksx10h/dayx5KBtu/hresistance
700KBtu/10Fdehumidification
dehumidification.
People have done it and it works. Somewhere something isnt adding up right... but where I really dont know.
Subject: Air / Earth Tubes Newsgroups: alt.solar.thermal Date: 2003-03-29
and the appallingly written
NT
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