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Formula of Heat Release Rate
The heat release rate formula from the first law of thermodynamics is given by,
ΔQc = ΔW + ΔQh + ΔU
Where,
- Qc is the Chemical energy released in KJ/Kg
- W is the Work output in KJ/Kg
- Qh is the Heat transfer in KJ/Kg
- U is the Internal energy of the contents in KJ/Kg
Solved Examples
Example 1
Determine the heat released of a cylinder whose internal energy is 245 KJ/Kg and heat transfer is 420 KJ/Kg for the work 280 KJ/Kg.
Solution:
Given parameters are
Work = 280 KJ/Kg
Internal energy = 245 KJ/Kg
Heat transfer = 420 KJ/Kg
Substitute all the values in the given formula.
ΔQc= ΔW + ΔQh + ΔU
= 280 + 420 + 245
= 945 KJ/Kg
Therefore, Heat release rate = 945 KJ/Kg
Example 2
The heat produced in a burner is 280 KJ/Kg and internal energy is 430 KJ/Kg. Determine the heat transfer for the work done 260 KJ/Kg.
Solution:
Given parameters are,
Work = 260 KJ/Kg
Internal energy = 430 KJ/Kg
Heat transfer = 280 KJ/Kg
Substitute all the values in the given formula.
ΔQc = ΔW + ΔQh + ΔU
= 260+ 430 + 280
Therefore, heat release rate = 970 KJ/Kg