Question

You want to determine the kw/ton of a chiller. You have an ammeter, temperature, and pressure sensors but don’t have a water flow meter. How can you still make the measurement?

Answer 1

There is an elementary from basic thermodynamics that states that the rate of heat transfer Q equals the mass flow rate M times a constant (specific heat of water) times the delta T (Fluid temp out minus fluid temp in). In other words that the rate of heat transfer is directly proportional to mass flow rate.

So colling capacity = mass flow rate * specific heat capacity * delta T
so we can replace the mass flow rate with the heat transfer rate and find the colling capacity.

for the heat transfer rate, we have to use the thermal conductance and thermal resistance.

Using pressure sensors we can determine the flow rate using the following equation:
q = C π/4 (D2)2 *[2(P1-P2) / ρ(1 – d4) ]1/2

q= flow rate
C= is the discharge cofficient and this is area ratio.
P1, P2 pressure.
ρ = fluid density
D2= nozzle inside diameter.
D1=upstearm and downstream pipe diameter.
d = D2/D1 ratio.