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Last updated date: 15th Sep 2024
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Heat load can be defined as the amount of temperature that can be added to a space to reach an acceptable range of energy. Heat load is also alternatively named as the heating load. Similarly, the amount of heat that can be removed from a space to maintain an acceptable range of energy is called a cooling load.  The heat source of any system can be defined by two systems.

The heat source can be external or the heat source can also be internal. The heat source can be defined as a system or a body that radiates heat (thermal energy). It can also be alternatively defined as the source from which heat energy is passed to the heat sink. As mentioned earlier the heat source can be categorized as external or internal. The internal source can be attributed to the inter particular friction and many other formulas. The external heat has a significant characteristic that heat is added from any source and leaves the space.

The heat load of any system is denoted by (Q). the heat load unit can be defined as watt, which is denoted by (w). The heat load calculation formula can be represented as the following,

Q = m × Cp ×ΔT

Heat load = mass flow rate × specific heat × change in temperature

The factors in the heat load formula are defined as the following

Q is defined as the heat load. The unit of the heat load is kilowatt, the heat load unit is represented as (kW).

m can be explained as the rate of mass flow of a fluid. Mass flow rate can be defined as the amount of mass of the fluid passing through the given space per unit of time. The mass flow rate can also alternatively defined as the rate of flow of fluid per unit area. Factors influencing it are as follows, the cross-sectional area, the viscosity of the fluid, the velocity of the fluid, and the density of the fluid. The unit of the mass flow rate is represented as (kg/s).

Cp can be defined as the specific heat of the system. Specific heat of any system is defined as the amount of heat required to raise the unit temperature of the unit system. Alternatively defined as the heat required to raise the temperature by one degree celsius for one gram of an object. The unit of specific heat can be defined as the J/(kg °C) or equivalently J/(kg K).

ΔT is defined as the change in the temperature of the fluid from point A to point B. change in temperature is usually calculated by subtracting T2 from T1. The unit of temperature is kelvin or celsius represented as (K or C).

### Examples of Heat Load Calculation

Here are some of the examples that explain how to calculate heat load using the heat load calculation formula.

Example 1

Calculate the heat load of an electric convertor whose mass flow rate is 6.75 and the specific heat of the system is 1000 and the enthalpy ranges from 21.5 to 26.55.

Solution-

Following data are given

m= 6.75

Cp = 1000

ΔT= 26.55- 21.5

Now substituting the values in heat load formula

Q = m × Cp ×ΔT

Q= 6.75 × 1000 × ( 26.55 - 21.5)

Q=  34087.5 W

Example 2

Heat load calculation of a system that has specific heat 200 and the mass flow rate is 4.20 and the difference in temperature ΔT is 5

Solution-

ΔT = 5

m= 4. 20

Cp= 200

Substituting the values

Q = m × Cp ×ΔT

Q= 4.20 × 200 × 5

Q = 4200 W

### Conclusion

Heat load is a term used to define the amount of temperature that can be added or removed from the system to maintain the temperature at an acceptable range. The heat load formula is represented by  Q = m × Cp ×ΔT. Where Q represents the heat load, m represents the mass flow rate and Cp represents the specific heat. The temperature difference is calculated by subtracting T2 from T1. the heat load unit is defined in Watts.

## FAQs on Heat Load Formula

1. What is the SI Unit of Heat Load or Heat Load Unit?

Ans- The heat load is represented as Q, the SI unit of Q is a watt, which is denoted by W.

2. Define Mass Flow Rate.

Ans- Mass flow rate can be defined as the amount of fluid flowing through the given space per unit time, the SI unit of mass flow rate is (kg/s).

3. What are the Factors Affecting the Internal Heat of the System.

Ans- The following are the factors that affect the internal heat of the system, temperature, pressure, volume, and state of matter.