7/17/2019 Water Heating Time Calculating

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Water Heating Time Calculations

The specific heat of water is 4.186 J/g°CThe equation for calculating the needed energy value for a certain water heating process is:

 Q=c*m*(dT)

c-specific heat (J/g°K) of the heated liquid

m- the mass of the liquid that needs to be heated (g)

dT- temperature difference during the process (°K)

Q- needed amount of energy for the process (J)

For example: In order to heat up 200L of water from 45°C to 90°C, we'll use the equationabove:

  Q = 4.186 J/g K *200,000g * 45K = 37,674,000J

Conversion of the energy (Q) to power (P): 1 Watt=1 J/s

Thus, in order to calculate the time needed for the process (given a heating element of2000W power) :

t(s)=Q/P

 time=37,674,000J/2000(J/s)=18,837s=313.95min=5.23h=05:14:00Meaning, it takes about 5 hours to heat up 200L of water from 45°C to 90°C with 2000Wheating power.

A few examples of the time needed to heat up various volumes of water in differentpowers:

 Assumptions: Optimal contiditions, no heat is lost to the environment, full conversion of theheating element's voltage into heat.

Water volume(L) Power (W) Heating time (H:M:S) from RT 25°C to:

50°C 70°C 85°C

60 L

1500W 01:10:00 02:06:00 02:47:00

2000W 00:52:00 01:34:00 02:00:00

3000W 00:35:00 01:03:00 01:24:00

100L

1500W 01:57:00 03:30:00 04:40:00

2000W 01:27:00 02:37:00 03:30:00

3000W 00:58:00 01:45:00 02:20:00

200L1500W 03:53:00 02:00:00 09:19:002000W 02:55:00 05:14:00 07:00:00

3000W 01:57:00 03:30:00 04:40:00

If we were to increase the power twice- the heating time will shorten in half for the samevolume, and so on.