I am sorry for not being able to devote time to RE as I have been a bit busy lately with some of the projects.

I am maintaining the Room Temperature at -1oC with a Te of -5oC. For humidification I have been using an adiabatic humidifier which is maintaining 95 to 97% RH. With this the core temperature of Grapes are being maintained at 0oC which as per requirement.

Now I am going to remove the adiabatic humidifiers and use EEV with an EPR so that I can reduce the Td. Theoritically this should work. Now let me see if this is practically possible. Injecting hot gas as suggested by Deb is also a good idea, as it will increase the Superheat as it is quite possible that the superheat may be reduced to such an extent by the reduction of Td that the compressor will be ineffective.