2 replies to this topic

can we represent closed cycle like refrigeration cycle in chemcad becuse it needs a feed stream to be defined

[djack77494]

I would think you could add a mixer and have two feeds. One is your circulating refrigerant. The second would be an artificial feed stream at the same conditions and composition. Just downstream of the mixer, add a splitter and remove a quantity of the mixture that matches the artificial feed stream you just added. If conditions of temperature, pressure, and composition haven't changed, you will do nothing but keep your simulator happy.
Doug

can we represent closed cycle like refrigeration cycle in chemcad becuse it needs a feed stream to be defined

[joerd]

Another option is to keep the loop open. Break it just after the condenser (= at the accumulator). At that point, you know the temperature (ambient + approach, or cooling water + approach) and the vapor fraction (=0). The composition is the refrigerant bulk composition. So let your simulator figure out the pressure.
The only thing you don't know is the flow rate. I don't know about Chemcad, but Hysys can back-calculate it from the chiller duties if you set everything up without mixers. Otherwise, you need to specify (guess) a flow rate, and see if you get liquid at the lowest pressure suction scrubber. If that is the case, you have to lower the circulation rate - which may be done automatically.