How many energy requires to increase 1℃ of 1 liter of water using MICROWAVE?

[Tamilarasan]

we planning to heat water directly using microwave for industrial purpose. we need only 33deg Celsius for that I need this.

 

[Baluncore]

Welcome to PF.

It was 1 calorie per gram per deg C. Now in SI units...
Assume no phase change.
Specific heat capacity of water is about 75.375 ± 0.05 J/mol·K
The molecular weight is 18 and density is 1.00
So to increase the temperature of 18g = 18 ml of water 1°C takes 75.375 joule.

1 litre will require (1000 / 18 ) * 75.375 = 4187.5 joule per deg C.

A rise of 33°C will require 4187.5 * 33 = 138187.5 joule.
If your microwave generator delivers 500 watt that is 500 joule per second.
It will take 138187.5 / 500 = a minimum of 275 seconds to heat one litre 33°C.

 

[mfb]

The power that has to go into the water is simply the temperature difference multiplied by the thermal capacity of the water (4.2 J/(g*K)), for a temperature change of 1 K ("1℃") this is 4.2 J/g.

Other considerations: Microwaves lose about 50% of their energy in the generation of the microwaves. A simple resistive heater could save half the power and simplify the setup, and a heat pump could save even more power (but make it more complicated). Cooling the microwave generator with the water would be possible as well, and would improve the efficiency. Or cool something else if possible.