What is pulsating heat pipe?
One such thermal device is the recently invented pulsating (called also oscillating) heat pipe (PHP). It consists of a closed capillary tube folded into meander and partially filled with a liquid. One side of the meander is in thermal contact with a hot spot, the other with a cold spot.
How does a pulsating heat pipe work?
The tube is first evacuated and then filled partially with a working fluid, which distributes itself naturally in the form of liquid-vapor plugs and slugs inside the capillary tube. One end of this tube bundle receives heat, transferring it to the other end by a pulsating action of the liquid-vapor/bubble-slug system.
What is inside a heat pipe?
A typical heat pipe consists of a sealed pipe or tube made of a material that is compatible with the working fluid such as copper for water heat pipes, or aluminium for ammonia heat pipes. The working fluid mass is chosen so that the heat pipe contains both vapor and liquid over the operating temperature range.
Who invented heat pipes?
physicist George Grover
In 1963, Los Alamos physicist George Grover successfully demonstrated his invention of the heat pipe. Grover’s inspiration for the heat pipe came from rudimentary heat-conducting pipes used by British bakers more than 170 years ago.
Do Heat pipes work upside down?
The fact that the heat pipe works at all in the “upside-down” orientation ( < 0) is due, of course, to the wicking of the condensed fluid against gravity. Again, the manufacturer’s recommended maximum power is found to be conservative for this particular heat pipe.
Which limit can lead to choking of flow in a heat pipe?
Viscous forces prevent vapor flow within the heat pipe. Heat pipe operating near triple point with a very low vapor pressure – need to use a different working fluid. Vapor flow reaches sonic velocity when leaving the evaporator, choking the flow.
What happens to a pipe at 100 C?
What happens to a pipe at 100 C liquid? Metal expands when heated. Length, surface area and volume will increase with temperature. The degree of thermal expansion varies with different types of metal.
Do heat pipes work upside down?
What are CPU cooler heat pipes?
What is a Heatpipe Heatsink? A Heatpipe is a sealed copper tube that is under vacuum, and can transfer heat rapidly away from the source. The High thermal conductivity enables a heat pipe to transfer, and dissipate heat to a more convenient location through a capillary action.
Do heat pipes have liquid?
The most common heat pipe working fluid is water for an operating temperature range from 1°C to 325°C. Low temperature heat pipes use fluids such as ammonia and nitrogen. High temperature heat pipes utilize cesium, potassium, NaK and sodium (873–1,473°K).
What happens to a pipe at 100 C liquid?
What happens to a pipe at 100 C liquid? Metal expands when heated. Length, surface area and volume will increase with temperature. Thermal expansion occurs because heat increases the vibrations of the atoms in the metal.
Can heat pipes be bent?
Bendable heat pipes, which can be bent after fabrication as needed, are novel devices for thermal management. The effect of bending on temperature drop, performance and performance limits has also been investigated.
What are pulsating heat pipes and what do they do?
Abstract— Pulsating heat pipes (PHPs) are the new addition to. the wickless heat pipe family introduced by Akachi in 1990’s, in. last few decades this device acts as a promising source for cooling electronic devices where temperature difference between source and sink is very small.
What can heat pipes be used for in space?
Conventional heat pipe technology has been successfully applied in the last thirty years for the thermal management of a variety of applications like heat exchangers, economizers, space applications, and electronics cooling, to cite a few [2].
What are the dimensions of a PHP heat pipe?
A PHP consists of a plain meandering tube of capillary dimensions with many U-turns (Figure 1a). In contrast to a conventional heat pipe, there is no additional capillary structure inside the tube. There are two ways to arrange the tube: open loop and closed loop.
Which is the correct way to arrange a heat pipe?
In contrast to a conventional heat pipe, there is no additional capillary structure inside the tube. There are two ways to arrange the tube: open loop and closed loop. As the names suggest, in a closed loop structure, the tube is joined end-to-end (Figure 1b).