What is the main characteristics of heat pipe?
A heat pipe has an effective thermal conductivity much larger than that of a very good metal conductor, such as copper. Figure 4 shows a copper-water heat pipe and a copper pipe dipped into an 80°C water bath. Both pipes were initially at 20°C temperature.
What fluid is used in a heat pipe?
Working Fluids 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 is the working fluid in a heat exchanger?
The working fluid of a heat engine or heat pump is a gas or liquid, usually called a refrigerant, coolant, or working gas, that primarily converts thermal energy (temperature change) into mechanical energy (or vice versa) by phase change and/or heat of compression and expansion.
How does a heat pipe work?
The heat boils the fluid and pushes the fluid vapor to the colder region of the heat pipe. The colder region, which is typically coupled to a heat sink, is known as “the Condenser”. The fluid gives up its latent heat and condenses back to a liquid, and is again absorbed in the wick structure.
Do Heat pipes have liquid?
The heat pipe is partially filled with a working fluid and then sealed. The working fluid mass is chosen so that the heat pipe contains both vapor and liquid over the operating temperature range.
What is inside a heat pipe?
heatpipe is constructed using a metal tube that is sealed under a partial vacuum. Inside the copper heatpipe is an inner wick lining that acts as a capillary material for a small amount of fluid. Heat is then released as the vapor condenses back into a fluid.
What is the working fluid in a refrigerator?
The working substance in a modern refrigerators is called the coolant; the coolant changes from gas to liquid as it goes from higher to lower temperature.
What are some properties of an efficient working fluid?
A suitable fluid must exhibit favorable physical, chemical, environmental, safety and economic properties such as low specific volume (high density), viscosity, toxicity, flammability, ozone depletion potential (ODP), global warming potential (GWP) and cost, as well as favorable process characteristics such as high …
What is the purpose of heat pipe?
Heat Pipes are one of the most efficient ways to move heat, or thermal energy, from one point to another. These two-phase systems are typically used to cool areas or materials, even in outer space.
How much liquid is in a heat pipe?
Below 0 oC, the water freezes within the sintered wick structure but causes no damage due to expansion as the amount of liquid is so small. For example, a typical 6mm heat pipe that’s 150mm in length contains about 1cc of water. A quick note on heat pipe reliability. Heat pipes have been extensively tested for decades.