Design Considerations     Heat Transfer

Infraglo Gas Fired Infra-red Radiant Burners in Cooking Appliances

Infraglo gas fired infra-red radiant burners are designed and constructed to utilise natural, propane and butane gases at a variety of gas pressures, as well as some types of manufactured substitute gases.

Catering Grills or Broilers

Grills, or broilers, are used for cooking food by radiant heat. The most usual of appliance used in the UK is the overhead grill, or salamander, sometimes referred to as an overfired grill. In the United States and Canada these types of appliance are also referred to as broilers.

The Infraglo gas fired infra-red radiant burner is an ideal heat source for overhead grilling or broiling, salamandering, or gratinating, every type of food. By varying the distance between the burner's plaque surface and the food consistent cooking results can be achieved and they are usually attained by tilting or moving the cooking shelf. The European continental salamander which features a rising/lowering heat source above a fixed position cooking surface is also a suitable application.

Infra-red Radiant Cooking

With infra-red radiation penetration of the electromagnetic radiation below the surface of the food to be cooked will be limited to a little over 2mm, the major effect therefore being one of intense skin heating.

It follows that if the heat generated and absorbed at the surface of the food is small, as a result of placing the food at its maximum distance from the heat source, it will be quickly dissipated towards the centre of the food mass. Slight heat increases at the food's surface will enable more heat to be conducted towards the centre and help to shorten the cooking time. The surface of the food should not overcook because there is no build-up of heat at the surface, the internal temperature of the food remains low and there will only be a slow rate of moisture content loss. The rate of flavour and colour development will also be slow. The result being, say, "well-done".

Should the food be placed close to the heat source then the heat generated and absorbed at the food's surface will be larger than can be dissipated to the centre of the food mass, the result will be a high rate of surface evaporation and correspondingly high surface temperatures. The rate of browning and flavour development will be high, typical of "cooked rare" food.

Design Considerations (Fig 1)

All the air sufficient for safe combustion in an Infraglo burner is naturally entrained at the burner's gas inlet. This requires that the gas and air entry be positioned in a clean environment outside the cooking compartment where the entrained air will be free of products of combustion, and cooking fumes. It is recommended that the cooking compartment be sealed from the compartment where the gas air entry is positioned.

Whilst all the air necessary for safe combustion is entrained at the gas and air entry to the burner, a supply of clean air must be permitted to the burner plaque's outer surface when it is operating. This is normally provided by natural draught inducement from the outside of the appliance.

As much space as possible should be provided between the Infraglo burner and the combustion compartment walls for evacuating cooking fumes and to prevent vitiation.

The chief factors affecting the rate of infra-red heat transfer are:
a) The emisivity of the radiating and receiving surface
b) The temperature of the radiating surface
c) The distance between the radiant surface and the food's surface
d) The area of radiant surface

These factors can be effectively utilised with the Infraglo burner by blanking off selected areas of the burner's plaque surface to provide a heat intensity to suit the designed application, and to enable it to be distributed as evenly as possible over the required foot print whether it be a grill grid, a brander, griddle plate, or a pan base.

When gas is burned on the Infraglo plaque a surface temperature of close to 900oC can be achieved, and radiant energy is emitted. This radiation is in the form of electromagnetic radiation in the Medium Wave region of the infra-red spectrum (Wave length 2 - 4 microns). This wave band is ideal for application to cooking equipment because it provides suitable radiation penetration into foodstuffs and utensils so activating sufficient material molecules to convert the radiated energy to heat. The food mass, or the mass of the utensil's material will then more condusively conduct the generated heat to cook the food to specification.

Infraglo gas fired infra-red radiant burners are uni-directional, compared with electric elements where only 50% of the heat is emitted in the intended direction. Designed to direct their heat emissions onto the work area, whether it be a pan base or a grill, Infraglo burners thus ensure that little heat is lost or wasted, thereby providing superb heat recovery.

For more information on our full grill burner range, please contact us

Technical Information

top of page