Journal of Power and Energy Engineering, 2013, 1, 25-28
http://dx.doi.org/10.4236/jpee.2013.17005 Published Online December 2013 (http://www.scirp.org/journal/jpee)
Copyright © 2013 SciRes. JPEE
25
Research of I norganic Hea t Transfer Element Starti ng
Proprerty
Qiangqiang Chen, Xi Chen, Xiaowei Zhang, Jing Li, Song Zhang, Quan Ma, Shuang Li
China Petroleum Engineering Co., Ltd., Beijing, China.
Email: chenqiangqiang@dwell.cn
Received October 2013
ABSTRACT
This article studies the wall temperature distribution of inorganic heat transfer element in different working conditions
by experiments, and analyzes the impact of inclination angle, heating power, different kinds of cooling medium and
different inlet temperature of cooling medium on the starting property of inorganic heat transfer element.
Keywords: Inorganic Heat Transfer Element; Starting Property; Inclination Angle; Heating Power; Cooling Mediu m
1. Introduction
Just like heat pipe, inorganic heat transfer element is a
high efficient heat transfer technique. The air preheater, heat
recovery boiler and other equipment with this technique
are successfully used in the waste heat recovery and
heating process of petrochemical industry, and have made
a conducive social, economic and environmental benefit.
Inorganic heat transfer technique provides a new kind
of high efficient heat transfer element for the heat-ex-
change equipment, and also provides conditions for the
design of heat-exchange equipment with high effective-
ness and long-term life [1]. But in order to give full play
to the good properties of inorganic heat transfer element
and ensure the high effectiveness and long-term life op-
eration of equipment, the element must be reasonably
designed and have a good starting property. So the re-
search of inorganic heat transfer element starting proper-
ty is important to the reasonable design of inorganic heat
transfer equipment.
2. Experimental Research
2.1. Experimental Material and Thermocouple
Arrangement
The 1st and 2nd inorganic heat transfer elements are
shown as the Figures 1 and 2.
2.2. Experimental Equipment
The experiment was according to the methods of “GB/T
14812-93 Heat transfer property test methods of gravity
heat pipe” [2], and set up a complete heat transfer prop-
erty experiment table. The experiment table was con-
sisted of test rig leg, inorganic heat transfer element, heat
preservation system, cooling medium circulatory system
and appropriate measuring system, which are as shown in
Figure 3.
In the above picture: 1—Test rig leg; 2 Electric hea-
ting pipe jacket; 3—Thermal insulation layer; 4Inor-
ganic heat transfer element; 5Hinge pipe-host plate;
6—Cooling medium jacket; 7—Temperature measuring
point of thermocouple; 8—Rock wool thermal insulation
layer; 9—Slider lock equipment; 10Pressure-regula-
ting heating control box; 11—Low level constant tem-
perature water box; 12Water pump A; 13—High level
water box; 14—Inlet valve; 15Flowmeter; 16—Inlet
thin copper sheet; 17Outlet thin copper sheet; 18
Outlet valve; 19Water box; 20—Control valve; 21
Water pump B; 22—Temperature measuring computer
and indicating instrument.
2.3. Measurement of Mediu m Temperature in
the Pipe of Element
The inorganic heat transfer elements used in experiment
Figure 1. Geometric dimension and thermocouple arrange-
ment of 1st inorganic heat transfer element.
Figure 2. Geometric dimension and thermocouple arrange-
ment of 2nd inorganic heat transfer element.
Research of Inorganic Heat Transfer Element Starting Proprerty
Copyright © 2013 SciRes. JPEE
26
Figure 3. Sketch map of experimental equipment.
are in isolation, so the temperature cannot be measured
by inserting armored thermocouple into the pipe. Since
the heat release of adiabatic section and the wall resis-
tance is small, so the error of using the wall temperature
of adiabatic section to replace the temperature of work-
ing medium in pipe is small, we can consider the average
wall temperature of adiabatic section as the temperature
of medium in the element [3,4].
2.4. Inner Wall Temperatu re of Inorganic Heat
Transfer Element
The inner wall temperature of inorganic heat transfer
element can be calculated by subtracting the temperature
drop of pipe thickness from the temperature of outer wall,
or adding up the two temperatures.
Heating section:
ln(/ )
2π
e oi
wei weoe
Q dd
TT L
λ
= −
(1)
Cooling section:
ln(/ )
2π
c oi
wci wcoc
Q dd
TT L
λ
= +
(2)
In the above equation, Twei is the inner wall tempera-
ture of heated end, ˚C; Twci is the inner wall temperature
of cooled end, ˚C ; Tweo is the outer wall temperature of
heated end, ˚C; Tweo is the outer wall temperature of
cooled end, ˚C; Le is the length of heated end, m; Lc is the
length of cooled end, m; do is the external diameter of
pipe; di is internal diameter of pipe,m; λ is the thermal
conductivity of pipe wall, W /(m˚C); Qe is the heat trans-
fer quantity of heated end, W; Qc is the heat transfer
quantity of cooled end, W, Qe = Qc.
3. Experimental Results and Analysis
3.1. Starting Property of Element with Small
Inclination Angle
Experiment condition: Heating power Q = 250 W; Inlet
temperature of cooling medium Tg = 15˚C; Flow quantity
of cooling medium Gwater = 100 L/h; Inclination angle θ =
0˚ - 7˚. The starting property of inorganic heat transfer
element is as shown in Figure 4.
As shown, when the inclination angle θ is 0˚, the
adiabatic section temperature of inorganic heat transfer
element is gradually rising, which rises from room tem-
perature to 166˚C within 25 minutes. This is because that
the heat transfer element cannot be started normally, the
heat transferred to the heat end cannot be brought by the
cooling medium effectively, so it will raise the tempera-
ture. We find that when the inclination angle θ is 1˚, 2˚,
3˚ and 4˚, the heat transfer element also cannot be started
normally, just like the curve of 0˚; When the inclination
angle θ is 5˚and 7˚, the heat transfer element can be
started normally.
3.2. Starting Property of Element with Big
Inclination Angle
Experiment condition: Heating power Q = 500 W; Inlet
temperature of cooling medium Tg = 15˚C; Flow quantity
of cooling medium G water = 100 L/h; Inclination angle
θ are 90˚, 45˚and 15˚. The starting property of inorganic
heat transfer element is as shown in Figure 5.
Figure 4. Starting property of inorganic heat transfer ele-
ment with small inclination angle.
Figure 5. Starting property of inorganic heat transfer ele-
ment with big inclination angle.
Research of Inorganic Heat Transfer Element Starting Proprerty
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As shown, when the inclination angle θ are 90˚, 45˚
and 15˚, the starting property of inorganic heat transfer
element is good. The characters: When the heating power
is Q = 500 W, during the first 10 minutes of heating, the
surface temperature of inorganic heat transfer element
rises quickly, then drops in a small range (generally 2˚C
~ 3˚C) when reaches a certain temperature (about 38˚C),
which is the inflection po int on the curve; During 10 ~ 15
minutes, the temperature raise is gentle gradually; At
about the 25th minutes, the temperature is keeping a sta-
ble value, we can believe that the inorganic heat transfer
element is started totally and in a stable working state.
3.3. Starting Property with Same Inclination
Angle and Different Heating P ower
Experiment condition: Inclination angle θ is 45˚; Inlet
temperature of cooling water T g = 15˚C; Flow quantity of
cooling water Gwater = 100 L/h; Study the star ting prop-
erty of inorganic heat transfer element when the heating
power are 250 W, 500 W and 1000 W. The results are as
shown as Figure 6.
As shown, the wall temperatures of adiabatic section
under different heating power are in a same changing
trend, and all have a temperature drop inflection point on
the curve where the temperature is about 38˚C, which is
the same as Figure 5. With higher power, the surface
temperature of adiabatic section rises faster, the curve
slope is bigger, and the inflection point temperature is
higher; Then the temperature rises slowly, and gradually
reaches a stable state; The bigger of the heating power,
the higher of the adiabatic section surface temperature
under stable state.
3.4. Starting Property of Element with Different
Temperature of Cooling Medium
Experiment condition: Same inclination angle θ = 90˚;
Same flow quantity of cooling medium G water = 150
Figure 6. Starting property with same inclination angle and
differe nt heating power .
L/h; Same heating power Q = 1000 W; Different inlet
temperature of cooling water (Tg = 20˚C, 30˚C). Study
the starting property of inorganic heat transfer element.
The results are as shown in Figure 7.
As shown, the wall temperature of adiabatic section
with different inlet te mperature of cooling med ium are in
the same changing trend, and all have a temperature drop
inflection point on the curve where the temperature is
38˚C. With higher inlet temperature of cooling medium,
the surface temperature of adiabatic section rises faster,
the curve slope is bigger, and the inflection point tem-
perature is higher. The higher of the cooling medium
inlet temperature, the faster of the element starting and
the higher of the relevant temperature under stable state.
3.5. Starting Property of Element with Different
Kinds of Cooling Medium
Experiment condition: Same inclination angle θ = 90˚;
Same heating power Q = 500 W; Same flow quantity of
cooling medium G water = 200 L/h; Same inlet tempera-
ture of cooling medium Tg = 20˚C. Study the starting
property of inorganic heat transfer element with different
kinds of cooling medium (oil and water). The results are
as shown in Figure 8.
As shown, when the oil is used as the cooling medium,
within the first 10 minutes of heating, the temperature
rises faster, and the relevant temperature u nder stable state
is higher than the temperature when the water is used.
This is because the specific heat of oil is much smaller
than water, it needs to increase more temperature than
water when transfers the same quantity of heat, so the
temperature of inner medium is much higher.
4. Conclusions
1) When the inclination angle θ is 5˚ and abo ve 5˚, the
inorganic heat transfer element can be started normally,
and reach a stable state at about the 25th minutes when
continuously hea te d.
Figure 7. Starting property with different inlet temperature
of cooling medium.
Research of Inorganic Heat Transfer Element Starting Proprerty
Copyright © 2013 SciRes. JPEE
28
Figure 8. Starting property with different kinds of cooling
medium.
2) When the inclination angle θ is 0˚ to 4˚, the inor-
ganic heat transfer element cannot be started normally.
3) With the same inclination angle, the higher of the
heating power, the better of the starting property, while
the higher of the adiabatic section surface temperature
under the stable state; The higher of the cooling medium
inlet temperature, the faster of the element starting, and
the higher of relevant temperature under stable state.
4) When oil is used as the cooling medium, the starting
property is better than water, but the relevant temperature
under stable state is higher than the temperature when
water is used as the cooling medium.
REFERENCES
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[2] GB/T 14812-93, “Heat Transfer Property Test Methods of
Gravity Heat Pipe.”
[3] Z. D. Nan, “Thermodynamic Property of High Efficient
Heat Pipe Heat-Transfer Fluid and the Research of High
Efficient Heat-Transfer Mechanism,” Postdoctoral De-
gree Thesis of Dalian Institute of Chemical Physics, Chi-
nese Academy of Sciences, 2003.
[4] W. Chen and J. Zhuang, “The Inorganic Heat Transfer
Technique and Element Analysis,” Energy Research &
Utilization, 2000.