Water tank immersion heater

A similar problem in the thread "liquid friction equation" you can use the equations from this thread.

A quickie thumbnail calc gave about 100 kW as the heater requirement. I'm not sure any heater of that size would fit through the 2.5 inches.

Indeed. At mcmaster I could find a heater that would be able to screw in 2.1/2 with 18 KW of power. You have a good amount of water to push and heat, so... Have you ever thought about installing a passage water heater (not an accumulator) -maybe fueled by gas or diesel or wathever- before the tank to heat the water, and maybe use this lower power electric heater in the tank to adjust and keep the temperature just before use? It really seems to me that it would be even cheaper in the long term.

maybe something more like this diesel electric pressure washer?

Your heating requirement is actually between 110 to 1302 kW (depending on hot water temp 65 to 75 C. A tank immersion heater can be a slow or inadequate due to heat loss from the tank. You can consider a separate electric or gas heater which will take in cold water and heat to required temperature before going to the Gts.

Just to Americanize things, you have a 100 gallon tank, and you want to take 77 degree (F) and raise it to 167 degrees (F) in 10 minutes. My first thought was a domestic water heater (before I converted everything over). The largest of these I have seen is about 50 gallon, and they don't heat over maybe 110 degrees. They could possibly be used as pre-heaters (two of them?) to ease the burden on your heater in the 100 gallon tank. My other thought is that your heater in the 100 gallon tank might need to handle the heat with no water in the tank without destroying itself.

Bill

"My other thought is that your heater in the 100 gallon tank might need to handle the heat with no water in the tank without destroying itself."

The heater works via convection. For water, if the flow is free, convection coefficient is about 2000 w/m²°K (sorry those are not American units but I suppose you accept the ISO norm), in air (without water) the convection is in the range of maximal 50 i.e. a reduction factor of 40! So that your "other thought" is not realistic.

What can be done is a temperature and temperature growth rate control of the heater and decrease current if the trend is too high. The controller has to be quite fast if not the heating element can be destroyed. The best is to stop the heater when the tank will be empty and start again when water level is high enough.

The turbine has waterwash nozzles installed for both offline and online.

For the offline water wash only,

If I have the dimensions of the nozzle, flow and pressure of the water at the exit of the nozzle

Is it possible to find out the fall in temperature of the water exiting the nozzle assuming the inlet is around 70 Degrees C...?