Energy balance in evaporator. Thermal load and heat transfer rate

[frank]

As a rule of thumb, in chillers:

kWr = mass flow(m3/h) * deltaT

My understanding is that the formula is Q = mass flow x dh

m3/hr is not a mass flow but volume flow

[el_donks]

Hi el_donks,

I did not read your answer. Thank you, it makes sense to me. Actually I have thought about the possible error measurement. However my theoretial doubts are:

1- If i put the heater at 2 kW shouldnt I get 2 kW of frigorific power? (theoretically).
Yes, as long as the system reaches stability
2- How can i calculate the heat that the hydraulic pump introduces in the glycol solution? I am wondering also what the hydraulic energy (related with the flowrate value) has to do in the energy balance.
I'm not pretty sure about this. If you have a given cooling power, you could calculate losses as the difference between given cooling power and the cooling effect over the load(what you are cooling). This way you would get the total thermal losses, but i don't know how to calculate thermal losses due to friction or transmission.

Thanks!

Regards,

My understanding is that the formula is Q = mass flow x dh

m3/hr is not a mass flow but volume flow

That's correct. Beside the language error (I meant volume flow), due to water's density close to 1, and also the specific heat of water, you "can" round it to the given rule of thumb (term which I understand is a quick and not 100% exact rule to calculate something). Of course chillers work with water+glycol usually, so mix's density isn't 1, neither is the specific heat. So you can use this rule of thumb with fluids whose characteristics are similar to water's.