Calculate heat capacity for R134a

Hi,

I'm simulating a condenser in Matlab and I'm using the equation for Heat Exchanger 2p-TL in the mathworks documentation. I'm trying to calculate Cmin=cp*massflowrate. I've downloaded the r134a Property Tables , but there is no information about the heat capacity. I would like to know how is the heat capacity calculated in Simscape when using a two Phase Fluid. I've done my research, but when I calculate Q=Cmin*efficiency*(T_inlet_2p - T_inlet_TL) as in the mathworks documentation, it seems as if the heat capacity was to low for the required heat load.

Answer 1

[Yifeng Tang]

If you really want, you can use the data in r134aPropertyTables.mat to calculate the cp for both the liquid and the vapor phases, using the definition of Cp = dh/dT, where h=u+p*v, and p,u,v,T are all available in the table. You may find more information on the data structure of this .mat here: https://www.mathworks.com/help/simscape/ref/twophasefluidproperties2p.html

However, the Cp calculated this way may not be what you need on the two-phase fluid side if phase change happens inside the heat exchanger (which I suspect does happen). The latent heat part, instead of the Cp*dT part, is usually the majority part of the total capacity. So the Cmin=Cp*flow equation you mentioned is valid only for the TL side, or the 2P side if no phase change occurs.