The heating, ventilation, and air conditioning (HVAC）方程式.
空気の方程式
速度
米国単位
or for standard air (d = 0.075 lb/cu ft)
「d」を解くには:
V = Velocity (fpm)
Vp = Velocity Pressure (in. w.g.)
d = Density (lb/cu ft)
Pb = Absolute Static Pressure (in. Hg)
(Barometric pressure + static pressure)
T = Absolute Temp. (460° + °F)
メートル単位
or for standard air (d = 1.204 kg/m3）
「d」を解くには:
V = Velocity (m/s)
Vp = Velocity Pressure (Pascals or Pa)
d = Density (kg/m3）
Pb = Absolute Static Pressure (kPa)
(Barometric pressure + static pressure)
T = Absolute Temp. (273° + °C = °K)
熱流
米国単位
Q (sens.) = 60 x Cp xdx cfm x Δt
or for standard air (Cp = 0.24 Btu/ポンド – °F):
Q (sens.) = 1.08 x cfm x Δt
Q (lat.) = 4750 x cfm x ΔW (lb.)
Q (lat.) = 0.67 x cfm x ΔW (gr.)
Q (total) = 4.5 x cfm x Δh
Q = A x U x Δt
R = 1/U
Q=Heat Flow (Btu/hr)
Cp = Specific Heat (Btu/lb · °F)
d = Density (lb/cu ft)
At = Temperature Difference (°F)
AW = Humidity Ratio (lb or gr H2O/lb 乾燥空気)
Ah = Enthalpy Diff. (Btu/lb dry air)
A = Area of Surface (sq ft)
U = Heat Transfer Coefficient (Btu/sq ft · hr * °F)
R = Sum of Thermal Resistances (sq ft· hr · °F/Btu)
P = Absolute Pressure (lb/sq ft)
V = Total Volume (cu ft)
T = Absolute Temp. (460° + °F = °R)
R = Gas Constant (ft/°R)
M = Mass (lb)
メートル単位
Q (sens.) = 60 x Cp xdxl/sx Δt
or for standard air (Cp = 1.005 kJ/kg – °C):
Q (sens.) = 1.23 x l/s x Δt
Q (lat.) = 3 x l/s x ΔW (lb.)
Q (total) = 1.2 x l/s x Δh
Q = A x U x Δt
R = 1/U
Q=Heat Flow (watts or kW)
Cp = Specific Heat (kJ/kg – °C)
d = Density (kg/m3）
At = Temperature Difference (°C)
AW = Humidity Ratio (g H2O/kg 乾燥空気)
Ah = Enthalpy Diff. (kJ/kg dry air)
A = Area of Surface (m2）
U = Heat Transfer Coefficient (W/m2 . ℃)
R = Sum of Thermal Resistances (m2 . ℃/W)
P = Absolute Pressure (kPa)
V = Total Volume (m3）
T = Absolute Temp. (273° + °C = °K)
R = Gas Constant (kJ/kg °R)
M = Mass (kg)
全圧
米国単位
TP = Vp + SP
cfm = A x V
TP = C×Vμ
TP = Total Pressure (in. w.g.)
Vp = Velocity Pressure (in. w.g.)
SP = Static Pressure (in. w.g.)
V = Velocity (fpm)
Vm = Measured Velocity (fpm)
d = Density (lb/cu ft)
A = Area of duct cross section (sq ft)
C = ダクト継手の損失係数
メートル単位
TP = Vp + SP
l/s = 1000 x A x V
TP = C×Vμ
TP = Total Pressure (Pa)
Vp = Velocity Pressure (Pa)
SP = Static Pressure (Pa)
V = Velocity (m/s)
Vm = Measured Velocity (m/s)
d = Density (kg/m3）
A = Area of duct cross section (m2）
C = ダクト継手の損失係数
ファンの方程式
米国単位
cfm = 立方フィート/分
rpm = 1 分あたりの回転数
P = Static or Total Pressure (in. w.g.)
bHP = ブレーキ馬力
d = Density (lb/cu ft)
メートル単位
I/s = リットル/秒
m3/s = 立方メートル/秒
P = Static or Total Pressure (Pa)
kW = キロワット
d = Density (kg/m3）
ポンプの方程式
米国単位
gpm = ガロン/分
rpm = 1 分あたりの回転数
D = インペラ直径
H = Head (ft. w.g.)
bHP = ブレーキ馬力
温水同等物
- ａ． 1 ガロンの水 = 8.33 ポンド
- b. Specific heat (Cp) water = 1.00 Btu/lb °F (@ 68°F)
- c. Specific heat (Cp) water vapor = 0.45 Btu/lb °F (@ 68°F)
- d. 1 フィートの水 = 0.433 psi
- e. One ft. of mercury (Hg) = 5.89 psi
- f. 1立方フィート水 = 62.4 ポンド = 7.49 ガロン
- g. One in. of mercury (Hg) = 13.6 in.w.g. = 1.13 ft. w.g.
- h.大気圧 = 29.92 in.Hg = 14.696 psi
- 私。 1 psi = 2.31 フィート重量 = 2.04 インチ hg
メートル単位
I/s = リットル/秒
m3/s = 立方メートル/秒
rad/s = ラジアン/秒
D = インペラ直径
H = Head (kPa)
BP = ブレーキ馬力
温水工学の方程式
米国単位
gpm = ガロン/分
Q = Heat flow (Btu/hr)
Δt = Temperature diff. (°F)
ΔP = Pressure diff. (psi)
Cv = Valve constant (dimensionless)
whp = 水馬力
gpm = ガロン/分
bHP = ブレーキ馬力
H = Head (ft w.g.)
Sp. Gr. = Specific gravity (use 1.0 for water)
Ep = ポンプの効率
NPSHA = 正味正味吸引ヘッドが利用可能
Pa = Atm. press. (use 34 ft w.g.)
Ps = Pressure at pump centerline (ft w.g.)
V2/2g = 点 P における速度ヘッドs (ft w.g.)
PvP = Absolute vapor pressure (ft w.g.)
g = Gravity acceleration (32.2 ft/sec2）
h = Head loss (ft)
f = Friction factor (dimensionless)
L = Length of pipe (ft)
D = Internal diameter (ft)
V = Velocity (ft/sec)
さまざまな水温における圧力を水銀柱インチから水柱フィートに変換
水温
F F F |
60
∘
60
∘
60^(@) |
150
∘
150
∘
150^(@) |
200
∘
200
∘
200^(@) |
250
∘
250
∘
250^(@) |
300
∘
300
∘
300^(@) |
340
∘
340
∘
340^(@) |
フォートインチ Hg あたりの水頭差差動 |
1.046
1.046
1.046 |
1.07
1.07
1.07 |
1.09
1.09
1.09 |
1.11
1.11
1.11 |
1.15
1.15
1.15 |
1.165
1.165
1.165 |
メートル単位
Q = Heat flow (kilowatts)
Δt = Temperature diff. (°C)
ΔP = Pressure diff. (Pa or kpa)
Cv = Valve constant (dimensionless)
m3/s = 立方メートル/秒
l/s = リットル/秒
WP = Water power (kW) or (W)
m3/s = 立方メートル/秒
I/s = リットル/秒
Sp. Gr. = Specific gravity (use 1.0 for water)
BP = Brake power (kW)
E, = ポンプの効率
H = Head (Pa) or (m)
NPSHA = 正味正味吸引ヘッドが利用可能
Pa = Atm. press. (Pa – Std. Atm. press. = 101,325 Pa)
Ps = Pressure at pump centerline (Pa)
V2/2g = 点 P における速度ヘッドs (m)
PvP = Absolute vapor pressure (Pa)
g = Gravity acceleration (9.807 m/sec2）
h = Head loss (m)
f = Friction factor (dimensionless)
L = Length of pipe (m)
D = Internal diameter (m)
V = Velocity (m/sec)
電気方程式
米国単位
I = Amps (A)
E = Volts (V)
PF = 力率
R= ohms (Ω)
P = watts (W)
Bhp = ブレーキ馬力
メートル単位
kW = キロワット
I = Amps (A)
E = Volts (V)
PF = 力率
R = ohms (Ω )
P. = watts (W)
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