When you are required to heat a solid object, there are 2 options, direct heat transfer or radiant heat.

If the object to be heated is a solid and must be heated all the way through like an aluminum mould tool die, then direct heat transfer is best.

Heating elements such as cartridge heaters offer the best performance. This is usually because they can be high watt densities and the surrounding object to be heated will easily absorb the heat. This process called heat transfer. Correct element spacing is important to ensure even heating.

Certain processes such as thermoforming and vacuum forming use infrared radiant heating. This is because the object being heated is thin usually 2-6mm thick. The radiant heat is used to soften the sheet and then it is formed into its given mould shape using a process called vacuum forming.

Other solid objects that require heating use radiant heating usually to soften the surface such as process lines for shrink wrapping, drying, cooking and curing. The use of infrared lamps or heating elements are used. Infrared is preferred where a faster response in temperature control is required.

Heating of air or gasses is best done using finned heating elements. This is because finned elements allow for a greater surface area that the air/gasses can flow over to be heated.

Air/gas systems normally use a series of fan systems to push the air across the heating elements surface. Some gasses expand when released and so may not require the function.

The heating element watt density is determined by the air flow and the temperature required at the measuring point. Several heating points may be required depending on the distance the heat is required to travel. Adequate insulation should be used to reduce heat losses.

We have a range of finned heating elements suitable for this application

The heating of liquids should be considered carefully as there are several ways and types of elements you can consider. This is determined by the heating method you want to employ.

You can either heat the liquid directly from the inside of the vessel/tank or externally from the outside. Your choice will depend on the type of liquid to be heated.

If you are heating water, then heating from the inside is usually best way as this would allow for the best heat transfer/energy release method.

If corrosive liquids are required to be heated, then heating from the outside is best choice as the element is not in direct contact with the liquid so ensures the element will last as long as possible. We can also supply heating elements with special Teflon sheath or coating if it is not possible to heat from the outside.

The heating of oils and viscous liquids needs to be considered carefully, firstly if the liquid has a maximum allowable temperature the external heating is preferred because the vessel is heated first as this is slower and more gentle. If the liquid is viscous type (thick) then heating over a large surface area is preferred, this is because if the thick liquid is heated from the inside then the element would only around the immediate area of the element. This would give inaccurate temperature reading, damage or ruining of the liquid.

Generally thicker the liquid the slower the liquid should be heated and this is usually from the outside.