Auxiliary Heating

Hello Paul,

I am trying to figure out the optimum capacity of heaters in the tank for freeze protection.
However, I am bit confused with Tank Freeze protection energy and the tank heater capacity.

If I change the capaicty to 40 MW, the max. tank freeze protection energy output is 40 MW. If i make it 50, its goes to 50 MW.

How does the tank freeze protection energy always vary with the heater capacity.? As per my understanding it will be only dependent on volume and temperature of TES medium inside. How does changing the capaicty of heater always change the output of tank freeze protection energy.

In the results of my tests with a tank heater capacity of 25 MWt and tank heater efficiency of 0.98, the tank freeze hourly protection energy varies over the year between zero and 25.5102 MWh/h, which is what I would expect (25 / 0.98 = 25.5102).

By definition the heater capacity determines the maximum rate at which the auxiliary electric tank heaters can add heat to the fluid in the tanks.

Please see Section 4.1.3 in the physical trough reference manual for a detailed description of how SAM calculates storage freeze protection energy.

Best regards,
Paul.

Yes, what I could not get is, why does the tank freeze protection energy change with change in the MW of the heaters.
What I understand from the tank freeze protection energy requirement is the energy required during one hour of operation to maintain the temperature of tank at the set point mentioned. HOw could it change with changing the MW of the heaters.?

The capacity of the heaters determines the maximum energy that the heaters can deliver. If you specify a system with low storage freeze protection heater capacity, for some hours when more storage freeze protection energy is needed than the heaters can deliver, the heaters will not be able to supply the required energy. Modeling the same system with higher capacity would result in more freeze protection energy being delivered during those hours.

Best regards,
Paul.