Research of Inorganic Heat Transfer Element Starting Proprerty

doi:10.4236/jpee.2013.17005

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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)

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: [email protected]

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; 4—Inor-

ganic heat transfer element; 5—Hinge pipe-host plate;

6—Cooling medium jacket; 7—Temperature measuring

point of thermocouple; 8—Rock wool thermal insulation

layer; 9—Slider lock equipment; 10—Pressure-regula-

ting heating control box; 11—Low level constant tem-

perature water box; 12—Water pump A; 13—High level

water box; 14—Inlet valve; 15—Flowmeter; 16—Inlet

thin copper sheet; 17—Outlet thin copper sheet; 18—

Outlet valve; 19—Water 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

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

= −

(1)

Cooling section:

ln(/ )

2π

c oi

wci wcoc

Q dd

TT L

= +

(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

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

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

[1] Z. Yu, “Prospectus of Application for Invention Patent-

Superconductor Transfer Element,” 1999.

[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.