Loop Heat Pipes

晨怡热管 2008-4-24 0:04:09

Loop heat pipes (LHPs) are hermetically sealed heat-transfer devices, possessing a superflow thermal resistance and operating on a closed evaporation-condensation cycle with the use of a "capillary mechanism" for pumping the working fluid. LHPs are capable of transferring heat flows from several watts to several kilowatts at a different orientation in the gravity field and zero-g conditions without the use of any additional energy sources. LHP Schematic Diagram

Advantages of LHPs:

high heat-transfer capacity;
no mechanically mobile parts;
low specific consumption of materials;
reliability in operation;
no need to provide a regular service;
adaptability to different arrangement conditions;
practically unlimited operating resource;
wide opportunities for various design embodiments.
low sensitivity to changes of the position in space;

Main Technical Characteristics of LHPs

maximum capacity, W	100 … 2000
thermal resistance, °С/W	0,02 … 0,2
operating temperature, °С	-20 … 180
effective length, m	0,2 … 20
evaporator diameter, mm	5 … 30
diameter of vapor line and condenser line, mm	1,8 … 8

At present LHPs are successfully used in systems of thermal regulation of space equipment.

Promising fields of practical application:

cooling of computers,
cooling of electronic and electrotechnical devices,
systems of heating of different objects,
low-potential heat recovery, etc.

LHP Experimental Models

Ammonia LHP
(20 m in length, capacity of 1.7 kW)

LHP with a disk-shaped evaporator
(30 mm in diameter)

LHP in Tests
(2 m in length)

Main achievements:

creation of loop heat pipes - highly efficient heat-transfer devices for different purposes;
creation of new capillary-porous materials for heat-transfer devices with high capillary-transportation characteristics.

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