Introduction of Micro Heat Pipe

As shown in the diagram of heat transfer principle of heat pipe, one end of the heat pipe is evaporation zone (heat in) and the other end is condensation zone (heat out). When the evaporation zone is heated, liquid working-fluid in capillary wick is vaporized, the vapor flows  to  the  condensation  zone  driven  by  the  pressure  difference between the hot evaporation zone and the cold condensation zone and then condensates in the condensation zone. The working-fluid, which is transformed into liquid, flows from the condensation zone to the evaporation zone along the capillary structure driven by the capillary pressure. In a cycle like this, heat is transferred from one end to the other of the heat pipes.

Different applied environment and working conditions requires different micro heat pipe with a different structure and heat transfer performance. The heat transfer performance of micro heat pipes relies heavily on the capillary wick structure in the inner surface, so design and manufacturing technology of the wick structure is the key and critical factor in the production process of the micro heat pipe at all time.

According to different wick structure, micro heat pipe includes three types: grooved heat pipe, sintered heat pipe and composite heat pipe.
 

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Micro heat pipe structure and working principle

Heat Pipe Products

• Heat Pipe Display
• Straight Heat Pipe
• Flat Heat Pipe
• Special-Shaped Heat Pipe

Heat Pipe Type

Diameter (mm):      1，2，3，4， 5，6，8，10，9.5，12，12.7，16，22
Length（mm）:      60～1000

Diameter(D)	Standard Length(L)	Ineffective Length（A)	Ineffective Length（ B）
1±0.05mm	60～300±1mm	1~3.0mm	1~6.0mm、＜8mm
2±0.05mm	60～300±1mm	1~3.0mm	1~6.0mm、＜8mm
3±0.05mm	60～300±1mm	2~5.0mm	4~7.0mm、＜ 10mm
4±0.05mm	60～300±1mm	2~5.0mm	4~7.0mm、＜ 10mm
5±0.05mm	60～300±1mm	2~5.0mm	4~7.0mm、＜ 10mm
6±0.05mm	60～2000±1mm	2~5.0mm	＜10mm
8±0.05mm	60～2000±1mm	3~5.0mm	＜10mm
9.5±0.05mm	60～600±1mm	<5mm	<14mm
10±0.05mm	60～600±1mm	<5mm	<14mm
12±0.05mm	60～600±1mm	<5mm	<15mm
12.7±0.05mm	60～600±1mm	<8mm	<15mm
16±0.05mm	60～600±1mm	<8mm	<15mm
22±0.05mm	60～600±1mm	<8mm	<15mm

 

 Bending Suggestion

R and Angle
Type	Min. R	Suggestion	Min.Bending Angle	Suggestion
Φ3	6	12	180 °>	180 °>
Φ4	7	16
Φ5	9	20
Φ6	9	24
Φ8	16	32
Φ10	18	40
Φ12	20	48

 

Width Table of Flatted Heat Pipe

Diameter	Thickness	Tolerance	Wide	Tolerance	Diameter	Thickness	Tolerance	Wide	Tolerance
Φ3	2.5	±0.05	3.32	±0.15	Φ6	3.5	±0.05	7.6	±0.15
	2		3.65			3		7.84
Φ4	3.6	±0.05	4.3	±0.15		2.9		7.91
	3		4.68			2.5		8.13
	2.5		4.95			2		8.54
	2.3		5.08			1.5		8.86
	2.2		5.14			1.2		8.98
	2		5.24			1		9.05
Φ5	4	±0.05	5.75	±0.15	Φ8	5	±0.05	9.96
	3.5		6.03			4.7		10.16
	3		6.29			4.5		10.2
	2.5		6.54			4.2		10.45
	2.3		6.66			4		10.5
	2		6.8			3.8		10.58
Φ6	5.3	±0.05	6.62	±0.15		3.5		10.71
	5		6.82			3.2		10.9
	4.8		6.92			3		10.97
	4.5		7.08		Φ10 和Φ9.5		定制
	4.3		7.2		Φ12
	4.2		7.24		Φ12.7
	4		7.34		Φ16
	3.8		7.46		Φ22

 

Q-max Test Method For Heat Pipe

Test Method :
1. THeat Source=70±5℃
2. TCondencer  =50℃
3. DB=50mm
4. DA=50mm
5. TambieNIT  =25±3℃
6. Find the Q-max while T1-T2≤5℃

Q-MAX

 

Thermal Performance Test

pipe type：straight pipe  Heat Pipe by L=150mm

 

Data Obtained

Q-max Table (Watt)
Flatten Thickness	Ф5mm		Ф6mm		Ф8mm
	Min. Power	Avg. Power	Min. Power	Avg. Power	Min. Power	Avg. Power
T=2.5mm	35	36	38	40	40	45
T=3.0mm	35	38	40	43	52	55
T=3.5mm	40	41	42	45	57	60
Round Pipe	45	48	48	50	60	67

（Note: The data comes from the experimental results in 2008）

Thermal Performance Test

type：straight pipe    Heat Pipe by L=200mm

 

Data Obtained

Q-max Table (Watt)
Flatten Thickness	Ф5mm		Ф6mm		Ф8mm
	Min. Power	Avg. Power	Min. Power	Avg. Power	Min. Power	Avg. Power
T=2.5mm	28	30	30	32	35	40
T=3.0mm	30	32	33	35	40	45
T=3.5mm	33	34	35	40	55	58
Round Pipe	35	40	40	45	58	64

（Note: The data comes from the experimental results in 2008）

Thermal Performance Test 

 type： L pipe    Evaporator=50mm

（Note: The data comes from the experimental results in 2008）

 

Data Obtained

Q-max Table (Watt)
Specification	Ф6×150				Ф6×180				Ф6×200
Bending radius	R=18mm		R=12mm		R=18mm		R=12mm		R=18mm		R=12mm
Flatten Thickness	Min.	Avg.	Min.	Avg.	Min.	Avg.	Min.	Avg.	Min.	Avg.	Min.	Avg.
T=3.0mm	40	42	33	35	32	35	32	35	28	30	28	30
T=4.0mm	43	45	38	40	35	40	33	35	32	35	30	32
Round Pipe	52	55	45	48	48	50	43	45	40	43	38	40

 

 Thermal Performance Test

type：L pipe     Evaporator=40mm

Data Obtained

Q-max Table (Watt)
Specification	Ф6×150				Ф6×180				Ф6×200
Bending radius	R=18mm		R=12mm		R=18mm		R=12mm		R=18mm		R=12mm
Flatten Thickness	Min.	Avg.	Min.	Avg.	Min.	Avg.	Min.	Avg.	Min.	Avg.	Min.	Avg.
T=3.0mm	32	33	29	30	29	30	27	28	25	27	23	25
T=4.0mm	33	35	30	32	30	32	29	30	28	30	26	28
Round Pipe	43	45	38	40	40	41	38	40	38	40	36	38

 

 Thermal Performance Test

 type：U pipe      Evaporator=50mm

 

Data Obtained

Specification	Ф6×150				Ф6×180				Ф6×200
Bending radius	R=18mm		R=15mm		R=18mm		R=15mm		R=18mm		R=15mm
Flatten Thickness	Min.	Avg.	Min.	Avg.	Min.	Avg.	Min.	Avg.	Min.	Avg.	Min.	Avg.
T=3.0mm	30	32	23	25	30	32	28	30	26	27	23	25
T=4.0mm	33	35	29	30	33	35	30	33	28	30	27	28
Round Pipe	42	45	37	38	40	43	38	40	38	40	35	37

Thermal Performance Test

 type：U pipe       Evaporator=40mm

 

Data Obtained

Specification	Ф6×150				Ф6×180				Ф6×200
Bending radius	R=18mm		R=15mm		R=18mm		R=15mm		R=18mm		R=15mm
Flatten Thickness	Min.	Avg.	Min.	Avg.	Min.	Avg.	Min.	Avg.	Min.	Avg.	Min.	Avg.
T=3.0mm	27	28	25	26	23	25	20	23	21	23	20	22
T=4.0mm	30	32	28	30	29	30	26	28	27	28	24	26
Round Pipe	36	38	35	36	34	35	31	33	30	32	28	30

 

Relationship between power and length（Sintered Heat Pipe）

 

Relationship between power and length（Grooved Heat Pipe）

Relationship between power and thickness of heat pipe

Manufacturing Process of Heat Pipe

Heat Pipe Reliability Test

1.Testing diameter and △T
2.Heating at 150℃ for one hour
3.Testing diameter and  △T again
4.Heating at 150℃ for twelve hour again
5.Testing diameter and  △T again

Objective：

The purpose of this examination is to test the heat pipe stability which depends on how long the heat would change the shape and performance of the heat pipe in high temperature.

Isothermal test of heat pipe

1. Theat source =70℃±5℃
2. Heating Time    T≤15s
3. Check the temperature in upper edge of heat pipe T1
4. Check △T ，△T ≤4℃ , (△T =T-T1）。

Isothermal test of heat pipe

1.Theat source =70℃±5℃
2. Heating Time    T≤15s
3. Check the temperature in upper edge of heat pipe T1
4. Check △T ，△T ≤4℃ , (△T =T-T1）。

Objective：

The purpose of this examination is to see the stability of heat pipe, ensuring there are no defective goods after testing.

Thermal Cycle Test of Heat Pipe

Objective：

From testing ，the useful life and aging rate is revealed.

Our Heat Pipes

Operation Temperature 5~222℃
Burst Temperature(℃) 340℃（备注：增大壁厚可以提高破坏温度）
Useful Life@80℃operation temperature   ＞7年 Years

Heat Pipe Reliability Experiments

1. Useful life Test
2. Leakage Test
3. Performance Test
4.Thermal Cycle Test
5. Salt Spray Test