Application of heat pipe in high power LED lighting

LED (Light Emitting Diode), a solid-state semiconductor device that converts electricity directly into light. The heart of the LED is a semiconductor wafer. One end of the wafer is attached to a holder, one end is the negative pole, and the other end is connected to the positive pole of the power supply, so that the entire wafer is encapsulated by epoxy resin. The semiconductor wafer consists of two parts, one part is a P-type semiconductor, in which the hole dominates, and the other end is an N-type semiconductor, which is mainly electrons here. But when the two semiconductors are connected, they form a "PN junction" between them. When a current is applied to the wafer through the wire, the electrons are pushed toward the P region where the electrons recombine with the holes and then emit energy in the form of photons.
High-power LEDs are important applications for outdoor lighting, and their superiority is reflected in:
1. LED as a point source, if the design is reasonable, it can largely solve the traditional spherical light source directly, and must rely on light reflection to solve the problem of secondary light extraction and light loss;
2. The uniformity of the light-irradiated surface is controllable, and theoretically it can be completely uniform in the target area;
3. The color temperature is optional, so the application of LEDs with different color temperatures in different occasions is an important way to improve efficiency and reduce costs;
4. The space for technological progress is still very large. The development of high thermal conductivity metal materials will effectively improve the light efficiency of LEDs. For example, CREE has achieved a chip efficacy of 130-150 lm/W. The application of the key technology of the heat balance heat dissipation structure, under the premise of maintaining low cost and passive heat dissipation mode, can effectively reduce the thermal resistance, effectively reduce the PN junction temperature, and effectively reduce the PN junction temperature by using a high thermal conductivity medium and a new device/lamp overall structure. The junction operates within the allowable operating temperature to maintain the maximum amount of photon output.
I. Overview of heat pipes
1. The heat pipe is composed of a shell, a wick that acts as a capillary, and a working medium that transfers heat. The wick is firmly attached to the inner wall of the envelope and is infiltrated by the working fluid. The heat pipe itself forms a closed system of high vacuum, the structure of which is shown in Figure 1:
The working principle is: the heat generated by the high-power LED , the temperature of the liquid working medium rises by the heat conduction to the tube wall of the evaporation section and the immersion liquid of the working fluid; when it rises to a certain temperature, the liquid surface evaporates until it reaches The saturated vapor pressure, at which time the heat is transferred to the steam in the form of latent heat, and the saturated vapor pressure rises as the temperature of the liquid rises. Under the action of the pressure difference, the steam flows to the condensation section where the pressure and temperature are low, and condenses at the gas-liquid interface of the condensation section to emit latent heat. The released heat is transferred from the gas-liquid interface to the heat sink outside the tube through the heat conduction of the wick and the tube wall.
2. Characteristics of heat pipe technology:
(1) Excellent thermal conductivity The inside of the heat pipe mainly relies on the vapor and liquid phases of the working liquid to change heat, and the thermal resistance is small, so it has a high thermal conductivity.
(2) Irreversibility Due to the existence of temperature difference, heat is irreversible during transmission.

HP Adapter

Laptop power adapter charger for HP:

Laptop Brand Power Adapter
EliteBook 8440p 6530b 18.5v 3.5a, 7450
Compaq 6500b 6530b 6535b 6700b 6730b 6735b 6736b 19v 4.74a, 7450
Pavilion DV4 DV5 DV6-1000 CQ60 CQ61 18.5v 3.5a, 7450
COMPAQ Mini 19v 1.58a, 4017
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Pavilion DV4 DV5 DV5T DV6 G50 G60 G70 HDX16 18.5v 3.5a, 7450
dm4-1000 Dm4t-1000 Dm4t-1100 DV3-4000 CQ42 18.5v 3.5a, 7450
Compaq Presario CQ42 CQ57 CQ72 CQ56 CQ32 CQ32-101TX I84C 18.5v 3.5a, 7450
G62 Compaq Presario CQ42 CQ72 CQ62 CQ56 CQ32 593555-001 DM4 18.5v 3.5a, 7450
DV4 DV5 DV6-1000 DV6-1200 DV6-1300 18.5v 3.5a, 7450
DV4 SPARE 18.5v 3.5a, 7450
dv4-1120us dv4-1200 dv6-2150us dv6-2155dx dv6-1245dx 18.5v 3.5a, 7450
Pavilion DV1000 DV1100 D1200 DV1300 18.5v 3.5a, 4817
DV1000 M2000 18.5v 3.5a, 4817
EliteBook 2730p 2740 2760p Compaq 2710p nc6320 18.5v 3.5a, 7450
Compaq 320 321 325 326 420 620 621 421 19v 4.74a, 4817
Pavilion dv4000 dv4100 dv4300 dv4400 19v 4.74a, 4817
Compaq DV1000 G3000 G5000 18.5v 3.5a, 4817
dv4-5000 dv6-7000 dv7-7099 19v 4.74a, 4817
dv6-7200 dv7-7200 DV4-5000 DV7-7000 19v 4.74a, 4817
DV4 DV6 CQ60 CQ70 G50 G70 18.5v 3.5a, 7450
ProBook 4340s 4341s 19v 4.74a, 7450
Pavilion DV3 19v 4.74a, 7450
ProBook 4320s 4321s 4325s 4420s 4425s 4525s 18.5v 3.5a, 7450
dv2000 dv6400 dv6700 dv6800 dv6900 A900 V6400 18.5v 3.5a, 4817
Compaq 420 421 425 4320t 620 625 320 321 325 326 621 18.5v 3.5a, 7450
ProBook 6440b 6445b 6450b 6540b 6545b 6550b 6555b 19v 4.74a, 7450
Pavillion DV7 19.5v 4.62a, 7450
G42 G72 G32 DV7-4000 DV6-6000 DV5-2000 19.5v 4.62a, 7450
Presario CQ32 CQ42 CQ43 CQ56 CQ62 CQ72 19v 4.74a, 7450
Pavilion DV6 DV6-3000 DM4-1000 Envy 15 17 G4 G6 G7-1000 19.5v 4.62a, 7450
avilion dm3 dm3-dm3t-1000 CTO dm3-1000 dv4-3100 19.5v 3.33a, 4817
DV4 DV5 G50 G60 G61 G70 G71 HDX16 19v 4.74a, 7450
CQ40 CQ50 CQ60 CQ61 CQ70 CQ71 DV4 19v 4.74a, 7450
CQ60 CQ61 CQ40 CQ41 CQ45 CQ60 G60 G70 19v 4.74a, 7450
Pavilion dm3 CTO dm3-1000 dv4-3100 19v 4.74a, 7450
Compaq 6520 6520P 6520S 515 516 19v 4.74a, 7450
2000-425NR 19v 4.74a, 7450

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