Propylene Glycol To Improve Cyclings of Compressor in a Concentric Tube Evaporator

Hello all,
Currently I am Working on a 600W Concentric Heat Exchanger Type Evaporator. Compressor is Emerson Based KCN415LAG as Mentioned in my Previous Post.

No. of Thermal On off Cycles Were Observed To be 2 minutes to 4 minutes.

I am Planning to Introduce Latent Heat Storage Into the System & Got Somewhere Suggestions to Use Proylene Glycol - Water Solution for Holding Evaporator for Certain Minutes After Compressor Shuts Off.

My Questions Are:
1. What Percentage of Propylene Glycol - Water Solution To Be Used if I m targeting Evaporator Holding Temperature of -15.0 deg.C.
2. How Much the Latent Heat Value of Solution(i.e. Freezed Solution ) is Different From that of Pure Ice, 335kJ/kg.?


If am Misunderstanding Anythin or Any Else Info needed, Kindly let me Know.
Thanks.