This relates to a vapor compression cycle working on R134a. The dryness fraction variation is required to determine the two phase heat transfer coefficient and the specific heats for HX performance evaluation.
Dear Aryan
The question needs some clarifications for the way of making your research (theoretical or experimental, what parameters are given?). If you have the total mass flow rate of the refrigerant and the mass flow rate of one of the phases, it is easy to calculate it directly. But I do not think this is your case.
The quality of the refrigerant inside the heat exchanger can be determined by conducting energy balance between the two streams in each part (pre-heater and evaporator) using the heat transfer rates and the mass flow rates. The heat transferred to the non-phase changed fluid is equal to that of refrigerant. Knowing the latent heat of the refrigerant at the operating pressure, the quality can be evaluated.
For more details, please have a look to the attached file.
Best wishes
In the condenser the refrigerant enters as superheated gas and exit as liquid so no need for dryness fraction here. As for evaporator the liquid exiting the condenser is throttled to evaporator pressure and it will have the same enthaply of the liquid at exit of condenser. Therefor knowing enthalpies at saturation (liquid and gaseous states) and evaporator pressure you can then calculate the dryness fraction at evaporator entry.
In condenser or evaporator tubes, the regular approach used for two phase flow analysis can be applied to determine the quantities of interest. Either treating as homogenous or a separated flow, one can attempt modelling the two phase flows in condensers or evaporators individually. Please note that the dryness fraction can be estimated either by knowing the void fraction or applying the conventional heat balance involving latent heat exchange during phase change. It would be much easier to compute the two phase parameters if the gas/liquid mass flow rates are known already. For more info pls. refer to books on two phase flows. Regular boiling or condensation heat transfer correlations are available in the open literature that comes as handy while estimating the two phase heat transfer rates in condensers and evaporators.
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