System for calculating temperature of fluid inside pipe by using heat flux, outer surface temperature of pipe, and flow velocity of fluid
A system for calculating a temperature of a fluid inside a pipe by using a heat flux, an outer surface temperature of the pipe, and a flow velocity of the fluid includes a flow meter to measure the flow velocity of the fluid flowing inside the pipe, a heat flux meter to measure the heat flux passing through an outer surface of the pipe, a thermometer to measure the outer surface temperature of the pipe, and a calculator configured to calculate an internal fluid temperature, which is the temperature of the fluid flowing inside the pipe, by using the flow velocity of the fluid measured by the flow meter, the heat flux measured by the heat flux meter, and the outer surface temperature of the pipe measured by the thermometer.
1 . A system for calculating a temperature of a fluid inside a pipe by using a heat flux, an outer surface temperature of the pipe, and a flow velocity of the fluid, the system comprising:
a flow meter to measure the flow velocity of the fluid flowing inside the pipe;
a heat flux meter to measure the heat flux passing through an outer surface of the pipe, wherein the heat flux meter is disposed on an outer surface of the pipe;
a thermometer to measure the outer surface temperature of the pipe, wherein the thermometer is disposed on an outer surface of the pipe;
a calculator configured to calculate an internal fluid temperature, which is the temperature of the fluid flowing inside the pipe, by using the flow velocity of the fluid measured by the flow meter, the heat flux measured by the heat flux meter, and the outer surface temperature of the pipe measured by the thermometer;
a determination module configured to determine whether the internal fluid temperature calculated by the calculator is within a preset temperature range between a first temperature and a second temperature; and
a processor configured to, when the internal fluid temperature determined by the determination module is out of the preset temperature range, control the internal fluid temperature to be maintained within the preset temperature range,
wherein the calculator is further configured to calculate the internal fluid temperature by using a calculation algorithm that is pre-trained based on an internal fluid temperature equation
T
b
=
R
o
R
i
q
s
h
+
q
s
R
o
ln
(
R
o
/
R
i
)
k
+
T
o
wherein T b denotes the internal fluid temperature, R o denotes a radius of an outer diameter of the pipe, R i denotes a radius of an inner diameter of the pipe, q s denotes the heat flux passing through the outer surface of the pipe, h denotes a heat transfer coefficient of an internal fluid, k denotes thermal conductivity of the pipe, and T o denotes the outer surface temperature of the pipe,
wherein the calculation algorithm calculates and stores the heat transfer coefficient of the internal fluid in advance, by using an equation
h
=
Nu
x
d
i
for the heat transfer coefficient of the internal fluid, a Nusselt number equation, which is any one selected from among Nu=4.36, Nu=3.66, Nu=0.023(Re 0.8 Pr n ), and Nu=5.0+0.025(RePr) 0.8 according to a type and a state of the internal fluid, a Reynolds number equation
Re
=
ρ
υ
d
i
μ
,
and a Prandtl number equation
pr
=
c
p
μ
x
,
wherein Nu denotes a Nusselt number, d i denotes a diameter of the inner diameter of the pipe, χ denotes thermal conductivity of the internal fluid, Re denotes a Reynolds number, Pr denotes a Prandtl number, ρ denotes density of the internal fluid, v denotes a flow velocity inside the pipe, μ denotes a viscosity coefficient of the internal fluid, and C p denotes specific heat of the internal fluid, and
wherein the calculation algorithm calculates the heat transfer coefficient of the internal fluid by applying Nu=4.36 when the internal fluid flowing inside the pipe is a laminar flow and a magnitude of a heat flux discharged to the outside of the pipe is constant, applying Nu=3.66 when the internal fluid flowing inside the pipe is a laminar flow and the outer surface temperature of the pipe is constant, applying Nu=0.023(Re 0.8 Pr n ) when the internal fluid flowing inside the pipe is a turbulent flow, applying Nu=5.0+0.025(RePr) 0.8 when the internal fluid flowing inside the pipe is a liquid metal, applying n=0.4 when a temperature of the pipe is greater than an external temperature of the pipe, and applying n=0.3 when the temperature of the pipe is less than the external temperature of the pipe.
2 . The system of claim 1 , wherein the calculation algorithm calculates the internal fluid temperature equation by using a heat flux relational expression
q
f
=
(
R
o
R
f
)
q
s
,
an internal heat flux equation q f =h(T b −T t ), and an external heat flux equation
q
s
=
k
T
i
-
T
o
R
o
ln
(
R
o
/
R
i
)
wherein T i denotes the inner surface temperature of the pipe and q f denotes a heat flux flowing from the internal fluid to an inner surface of the pipe.
3 . The system of claim 2 , wherein the calculation algorithm calculates the inner surface temperature equation
T
i
=
q
s
R
o
ln
(
R
o
/
R
i
)
k
+
T
o
by rearranging the external heat flux equation
q
s
=
k
T
i
-
T
o
R
o
ln
(
R
o
/
R
i
)
in terms of the inner surface temperature of the pipe, calculates an intermediate fluid temperature equation
T
b
=
q
f
h
+
q
s
R
o
ln
(
R
o
/
R
i
)
k
+
T
o
by using the inner surface temperature equation
T
i
=
q
s
R
o
ln
(
R
o
/
R
i
)
k
+
T
o
and the internal heat flux equation q f =h(T b −T t ), which is pre-trained, and calculates the internal fluid temperature equation by using the intermediate fluid temperature equation
T
b
=
q
f
h
+
q
s
R
o
ln
(
R
o
/
R
i
)
k
+
T
o
and the calculated heat flux relational expression
q
f
=
(
R
o
R
i
)
q
s
.
4 . The system of claim 1 , further comprising a heating module configured to, when the determination module determines that the internal fluid temperature is less than the first temperature, increase the internal fluid temperature under control by the processor.
5 . The system of claim 1 , further comprising a cooling module configured to, when the determination module determines that the internal fluid temperature is greater than the second temperature, reduce the internal fluid temperature under control by the processor.