① When there is a temperature change Δt in a process, the heat absorbed (or released) is represented by Q. Q denotes heat (Joules).
Q = c·m·Δt.
Q absorbed = c·m·(t－t0)
Q released = c·m·(t0－t)
(t0 is initial temperature; t is final temperature)
C is the specific heat capacity related to the process.
The unit of heat is the same as that of work and energy. In the International System of Units, heat is measured in Joules (J), named after the scientist James Prescott Joule. Historically, the unit of heat was defined as a calorie (cal), used as an auxiliary unit of energy, where 1 cal = 4.184 J.
Note: 1 kcal = 1000 cal = 1000 calories = 4184 J = 4.184 kJ
Heat absorbed, released, and stored in a specific area over a period maintains a balance.
ΔT = (t1 - t0)
② Calculation formula for heat released by the complete combustion of solid fuel: Q released = mq. For gaseous fuel: Q = Vq, where Q denotes heat (J), q denotes calorific value (J/kg), m denotes the mass of solid fuel (kg), and V denotes the volume of gaseous fuel (m^3).
q = Q released / m (solid); q = Q released / v (gas)
W = Q released = qm = Q released / m, W = Q released = qV = Q released / v (W: total work)
(Calorific value depends on pressure)
International System of Units (SI):
Q — Heat released by the complete combustion of fuel — Joules (J)
m — Mass of the fuel — Kilograms (kg)
q — Calorific value of the fuel — Joules per kilogram (J/kg)
Heat Calculation Formula:
Q = Δt * m * C
(C is the specific heat capacity, m is the mass, and Δt is the temperature difference)
© 2024 NoxToolbox