THREE QUESTIONS TEST
- What is the merit of cooling a place using AIR, a good insulating medium, with low thermal capacity?
- If you want to empty a tank, do you pump it out or would you rather drain it?
- Which heat transfer process would you choose: A or B?
- linearly proportional to temperature difference (i.e. doubling ∆ T = 2 x heat transfer rate)
- proportional to 4th power of temperature difference (i.e. doubling ∆ T = 16 x heat transfer rate)
LETS EXPLORE WHY
Thermal Conductivity | Specific Heat Capacity | Density | |
(W/mK) | (W/kg.k) | (kg/m3) | |
Air | 0.03 | 1.004 | 1.225 |
Water | 0.6 | 4.18 | 1000 |
Water presents a significantly higher heat transfer capacity:
- The multiplier of specific heat capacity and density for water vs. air is ~ 3400 (heat absorption per unit volume)
- The thermal conductivity multiplier for water vs. air is ~ 20 (heat transfer per unit area per unit thickness)
Medium | Cooling Capacity | Flowrate Required | Power Required |
Air | 100 TR | ~ 40,000 cfm | 22 kW |
Water | 100 TR | ~32 cfm | 3.7 kW |
SAMPLE IMAGE
RELATED PASSIVE DESIGN
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