① The heat absorbed (or released) when the temperature changes by Δt in a process. Q represents heat (J).
Q=c·m·Δt．
Q_absorbed = c·m·(t - t₀)
Q_released = c·m·(t₀ - t)
(t₀ is initial temperature; t is final temperature)
Where 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, the unit of heat is the joule (abbreviated as J) (named in honor of scientist Joule). Historically, the calorie (abbreviated as cal) was defined as a unit of heat, used only as an auxiliary unit of energy, 1 cal = 4.184 J.
Note: 1 kilocalorie (kcal) = 1000 cal = 1000 calories = 4184 J = 4.184 kJ
The equilibrium relationship between heat absorbed, released, and stored in a certain area during a certain period.
△T=（t1-t0）
② Formula for heat released by complete combustion of solid fuel: Q_released = mq; for gaseous fuel: Q_released = Vq. Q represents heat (J), q represents calorific value (J/kg), m represents mass of solid fuel (kg), V represents volume of gaseous fuel (m³).
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 is related to pressure)
SI international units:
Q — heat released by complete combustion of a certain fuel — joule (J)
m — mass of a certain fuel — kilogram (kg)
q — calorific value of a certain fuel — joule per kilogram (J/kg)
Thermal energy formula
Q=△t*m*C
(Specific heat capacity is C, mass is m, Δt is temperature difference)