Heating Up Applications - Energy Required and Heat Transfer Rates
The energy required to heat up a substance - like a tank, swimming pool or similar - within a certain time can be calculated as
q = m cp dT / t (1)
where
q = mean heat transfer rate (kW)
m = mass of substance (kg)
cp = specific heat of the substance (kJ/kg oC)
dT = temperature difference (oC)
t = heat up time (s)
Note that heat loss to the surroundings will extend the heat up time.
Example - Heating up an Aluminum Saucepan filled with Cold Water
An aluminum saucepan with weight 2 kg is filled with 10 liter cold water with temperature 0 oC and heated to temperature 100oC (boiling) in one hour. The heat transfer rate (or required power) can be calculated as
q = [( (10 liter) (1 kg/liter) (4.2 kJ/kgoC) + (2 kg) (0.91 kJ/kgoC) ) ( (100 oC) - (0 oC) )] / [(1 h) 3600 (s/h)]
= 1.2 kW
The energy consumed can be calculated as
E = q t (2)
where
E = energy (kJ, kWs)
t = time (h)
- or, with values
E = (1.2 kW) (1 h)
= 1.2 kWh
Related Topics
• Thermodynamics
Work, heat and energy systems.
Related Documents
Carnot Efficiency
The efficiency of the Carnot cycle.
Cooling Load - Latent and Sensible Heat
Latent and sensible cooling loads to consider when designing HVAC systems.
Electric Heating of Mass
Electric heating of an object or mass - temperature change vs. energy supplied.
Energy Transfer Equation
Fluid energy transfer.
Heat, Work and Energy
Heat vs. work vs. energy.
Heating System Flow Rates
Calculate flow rates in heating systems.
Heating Systems - Steam and Condensate Loads
Calculating steam and condensate loads in steam heated systems.
Hot Water Heating Systems - Online Design Application
Free online design tool for designing hot water heating systems - metric units.
Hot Water Heating Systems - Online Design Application, Imperial Units
Online design tool for hot water heating systems.
Liquids and Fluids - Specific Heats
Specific heats for some common liquids and fluids - acetone, oil, paraffin, water and many more.
Specific Heat of common Substances
Specific heat of products like wet mud, granite, sandy clay, quartz sand and more.
Steam Heating Processes - Load Calculating
Calculating the amount of steam in non-flow batch and continuous flow heating processes.