Quick Equations & Info Flashcards
What is the total heat equation for air?
Q[btuh]=density[lbm/ft^3] * 60min/hr * airflow[ft^3/min] * h[btu/lbm]
Standard density: Q=4.5CFMh[btu/lbm]
What is the sensible heat equation for air?
Q[btuh] = density[lbm/ft^3] * 60min/hr * Cp[btu/(lbm * F)] * airflow[ft^3/min] * T[F]
Typically: Q = 1.08 * CFM * T
What is the heat equation for water?
Q[btuh] = Cp[btu/(lbm*F)] * 60min/hr * density[lbmm/ft^3] *1/7.48[ft^3/gal] * gpm * T[F]
Typically: Q=500 * gpm * T
How do you convert a volumetric flow rate to velocity?
Divide volumetric flow rate by cross-sectional area of flow
Ex. GPM to ft/s in a pipe is (gal/min) * min/60s * 1/7.481(ft^3/gal) * 1/pi*r^2
Typically: gpm to ft/s is gpm * 1 / (1410 * r[ft]^2)
How do you convert a mass flow rate to a volumetric flow rate?
Divide the mass flow rate by the density
What is the density of air at standard conditions?
.075 [lbm/ft^3) @ 60[F] and 14.7[psi] or 1[atm]
What is the density of water at standard conditions?
62.4 [lbm/ft^3] @ 60[F] and 14.7[psi] or 1[atm]
How many BTU per W?
3.412 Btuh is equal to 1 W
What is the equation for equivalent diameter of a rectangular flow cross section?
D = 1.3 * (a * b)^.625 / (a + b)^.25
What is the Darcy-Weisbach equation for pressure drop in in. wg?
P [in. wg] = f * 12 * L [ft] / D [in] * p [lb/ft^3] * (V [ft/min] / 1097)^2
How many pounds of water in a gallon?
1 Gallon = 8.34 Pounds water
How many kW in a HP?
1 HP = .746 kW
How many gallons per cubic foot of water?
1 ft^3 = 7.48 gal
What are the specific heats of air?
Constant pressure: 0.24 [Btu / lbm * R]
Constant volume: .171 [Btu / lbm * R]
What’s the typical tone per well in a geothermal system?
1.3 ton/well. Confirm with a test well before final design.
