How to find the power factor of an electric motor (refrigerator)? continued...?

P

Parasite

New member
I am trying plot a graph of shaft power (W_shaft) and power factor (P_f) but have no idea how to find (P_f) or how to use it to make a graph. I obviously need to find the value at different values of (W_shaft) but don’t know how to do this either.

I have calculated the following values but now I’m stumped:
Compressor current (I_c), compressor speed (N_c), input voltage (V), motor shaft power (W_shaft).
I also have a torque arm radius (r) but don’t know how this fits in.

To find the power factor (P_f), I think need to find the electric power of the motor (W_elec) but don’t know how to do this without (P_f).
I know the equation for (W_elec = I_c ? V ? P_f) but I’m just going round in circles.

Please help.
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Further to this, I have measured values for the following:
Refrigerant inlet temperature to the compressor (T_1)
Refrigerant inlet temperature to the condenser (T_2)
Refrigerant inlet temperature to the expansion valve (T_3)
Refrigerant inlet temperature to the evaporator (T_4)
Water inlet temperature to the condenser (T_5)
Water outlet temperature from the condenser (T_6)
Evaporating pressure (p_1)
Condensing pressure (p_2)
Refrigerant flow rate (m_r)
Water flow rate (m_w)
Brake force (on torque arm) (F_b)
Compressor speed (N_c)
Compressor current (I_c)
Supply voltage (V)
Evaporator voltage (V_E)
Evaporator current (I_E)

I have also been given compressor bore & stroke, total swept volume, belt pulley ratio & torque arm radius.

Hopefully this helps you to help me :)
 
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