STIEBEL ELTRON Heat pumps, Техническое руководство

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SUmmary of formUlaE
Heat amount
Q = m
x
c
x
(t
2
– t
1
)
Q = Heat amount wh
m = water volume kg
c = specific heat wh/kgK
1 163 wh/kgK
t
1
= Cold water temperature °C
t
2
= DHw temperature °C
Heating output
Q = A
x
k
x
∆
ϑ
Q = Heating output w
A = surface m²
k = Heat transition coefficient
w/m²K
∆
ϑ
= temperature differential K
k value
1 + d + 1
α
i
λ α
a
1
k =
k = k value w/m²K
α
i
= Heat transfer
coefficient, internal w/m²K
α
a
= Heat transfer coefficient,
external w/m²K
λ = thermal conductivity w/mK
Connected load
P =
m
x
c
x
(t
2
- t
1
)
t x η
P = Connected load w
m = water volume kg
c = specific heat wh/kgK
t
1
= Cold water temperature °C
t
2
= DHw temperature °C
D = Heat-up times h
η = efficiency
Heat-up time T
D =
m
x
c
x
(t
2
- t
1
)
P
x
η
D = Heat-up time h
m = water volume kg
c = specific heat wh/kgK
t
1
= Cold water temperature °C
t
2
= DHw temperature °C
P = Connected load w
η = efficiency
Pressure drop calculation
∆p = l
x
r + Z
∆p = Pressure differential Pa
r = tubes frictional resistance
l = Pipe length (m)
Z = Pressure drop from the
individual resistances Pa
Individual resistances
Z = Σz
x x
v
2
ς
2
z = resistance coefficient
ς
= Density
v = Flow velocity (m/s)
Z can be taken from the total z and the
velocity in the pipework in the tables.
Duct work curve
∆p
1
∆p
2
V
1
V
2
) 2
=
∆p
1
= Pressure differential Pa
∆p
2
= Pressure differential Pa
V
1
= Air flow rate m³/h
V
2
= Air flow rate m³/h
Mixed water temperature
(m
1
x
t
1
) + (m
2
x
t
2
)
t
m
=
(m
1
+
m
2
)
t
m
= Mixed water temperature °C
t
1
= Cold water temperature °C
t
2
= DHw temperature °C
m
1
= Cold water volume kg
m
2
= DHw volume kg
Mixed water volume
m
2
x
(t
2
-
t
1
)
m
m
=
t
m
-
t
1
m
m
= Mixed water volume kg
m
1
= Cold water volume kg
m
2
= DHw volume kg
t
m
= Mixed water temperature °C
t
1
= Cold water temperature °C
t
2
= DHw temperature °C
DHW volume
m
m
x
(t
m
-
t
1
)
m
2
=
t
2
-
t
1
m
m
= Mixed water volume kg
m
1
= Cold water volume kg
m
2
= DHw volume kg
t
m
= Mixed water temperature °C
t
1
= Cold water temperature °C
t
2
= DHw temperature °C
Approximate heating load according
to oil consumption
Q
n
= b
a
x
h
x
H
u
/ b
VH
Q
n
= Heating load (kw)
b
a
= Annual oil consumption (l)
Average consumption over the
last five years, minus 75 litres
of oil per person for DHw
heating.
h = seasonal efficiency [to Din]
(h = 0.7)
H
u
= Calorific value of fuel oil
(10 kwh/l)
b
VH
= Hours run at full utilisation
(average value 1800 h/p.a.)
Q
n
= b
a
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