Heat Exchanger Technical Specifications

Ducts often transfer heat that is contained in gases.

Various industries use heat exchangers, including the aeronautical industry, the chemical processing industry, the automotive industry, cooling systems, food and beverage processing and domestic water use. Heat exchange systems, such as air conditioning systems and hydraulic systems, rely on heat exchange.

Heat Transfer Liquids

Various liquids act as refrigerants, which allow heat exchange systems to carry heat across a given area. Water and other refrigerants can have their temperatures mechanically altered and then travel through pipes where they carry the heat. They can then be placed in areas where they release the heat. Water is also sometimes heated to the extent where the water can turn into steam, which can raise the temperatures of other objects. Various oils also play a major role in cooling, such as the oils used in automotive systems.

Flow Rate

The liquid chosen for the heat system must have a good flow rate or else the liquid will not travel efficiently through the pipes or other passageways to areas that need a temperature change. Gases also have different flow rates depending on their density and other properties.

Air Exchange System

Air acts as an effective heat exchange system. Air conditioners and heaters create hot air that ductwork transports to areas that need the hot or cold air. These systems must take into consideration that hot air tends to rise and cool air tends to fall, so contractors tend to install heating systems in basements and other lower areas. Air cooled systems usually have a fan that moves the air in a given direction by chopping the air at a certain angle.

Temperature Range

Liquids and gases have temperature ranges at which they change properties. These substances must be able to perform the job at the temperature range that the system is normally subjected to.

Plates

Plates are sometimes used to increase or decrease the pressure of liquids and gases. These plates usually operate under 150 degrees Fahrenheit, since higher temperatures can weaken the plate. When the plates change the pressure of the substance, that substance will tend to flow at a higher rate.

Scraped Surface

Scraped surface heat exchangers have cylinders that contain rotating rows of scraper blades that circulate hot and cold air between the cylinder and the insulation jacket.

Shell and Tube

Shell and tube heat exchangers work great for systems that operate at very high temperatures and need very high pressures. U-tubes placed in a shell have liquid placed in the shell outside the U-tube. Then, a head assembly directs the heated liquid into the U-tube.

Common Materials

Engineers make heat exchangers out of a variety of materials, with different materials vulnerable at different temperatures and that also have heat conductivity that varies. Common materials used by engineers include aluminum, brass, copper, steel and titanium.

References

• Global Spec: Heat Exchangers
• Thermo Dynamics: Heat Exchangers