Heat load refers to the heat released per unit time when fuel is burned in burners (such as gas appliance, gas water heater, gas heating stove, internal combustion engine and rocket engine combustion chamber) in the field of internal combustion engines. In the burner, the calculation formula is: heat load = fuel consumption * low calorific value of fuel. The heat load is determined by the fuel consumption of the main burner and other factors.

Usually, the thermal load of parts is expressed by heat flux density, which can be expressed by different parameters in different situations. Under the action of heat flow, q=α(Tg-Tw), depending on the heat transfer coefficient and heat transfer conditions, will form a certain temperature field on the parts. Every point on a part can be characterized by its temperature and the temperature gradient around it. The greater the heat flow rate, the higher the temperature and thermal stress of the heated wall surface of the part.

The heat load of the extended data central heating system mainly includes heating, ventilation, hot water supply and production technology.

When making a heating plan or designing a heating system in a city or region, there is often a lack of accurate original data. Generally, it can only be estimated by the thermal index method, that is, the thermal index per unit building area is multiplied by the building area to get the design heating load Q (watts). Expressed as:

Q=qfF

Qf-thermal index of unit building area (w/㎡);

F- building area (㎡)