Loop Heat Pipe

Loop heat pipe (LHP)
a micro-technology for heat transfer   

What is loop heat pipe(LHP)

 A loop heat pipe (or LHP) is a two-phase heat transfer device.It uses capillary action to remove heat from a source and passively move it to a condenser or radiator. LHPs are similar to heat pipes but have the advantage of being able to provide reliable operation over long distance and the ability to operate against gravity. Different designs of LHPs ranging from powerful, large size LHPs to miniature LHPs (micro loop heat pipe) have been developed and successfully employed in a wide sphere of applications both ground based as well as space applications.

Loop heat pipe (or LHP) is a heat-transfer device utilizing a fine porous or wick structure in micro
scale to achieve remote heat transport with high power. The special features of LHPs are:
(1) Heat transport in long distance, can reach several meters distance.
(2) High power, as high as several hundreds Watt.
(3) Flexible, bendable connecting pipe.
(4) Anti-gravity operation, maintaining high heat transfer capability in anti-gravity direction.
(5) Passive heat-transfer device, no external power input.

The major application of LHP is in aerospace and at high cost. LHP is thought to be the next-generation heat-transfer device for the cooling of electronic device in commercial products, if the cost can be reduced in the future.

How it works

Loop heat pipe is a hermetic closed-loop device filled with working fluid. Vapor is generated by heating at the evaporator and flows to the condenser in which vapor is condensed into liquid due to heat dissipation to the surrounding. Liquid then flows back to the evaporator through connecting pipe by capillary force induced by a wick material inside the evaporator. Liquid is continuously supplied to the evaporator for evaporation again to complete a cycle. The wick is made of porous material with micro pores to act as a powerful capillary pump for returning liquid from the condenser.

Applications

Computer Cooling
To reduce the cabinet temperature and avoid internal components operating at high temperature which may cause unstable situation, the low-noise PC adopts ATD’s Loop Heat Pipe (LHP) to dissipate waste heat generated by CPU (heat source) and extend the lifetime of PC. The LHP transports waste heat trough copper pipe to the large area of the case, and we can reduce the using of fins or fans. As a result, the PC cooling by LHP becomes a new generation silent computer. Because of the flexible pipeline routing and unlimited operation orientation, we can use LHP to transmit waste heat of CPU through pipeline to a place much easier to make heat exchange, such as using PC case to dump heat by natural convection. To solve thermal problem inside PC with LHP, we can utilize limited inner space more effectively and even avoid resonant noise problem caused by fans of CPU, GPU and system fans etc.

Electrical Devices Cooling

LED light Cooling

Power storage cell