Double stage or single stage condensing unit?

[jency varghese]

Hello.
I have a testing chamber of size 1.75 x 1.8 x 0.5 meter. The room where the testing chamber is placed will be maintained at 25C. I am required to bring down the temperature inside the chamber from 25 to -30C in one hour time. I have done a refrigeration calculation and I got the following result 10HP, -35C Evaporator temperature. I have been offered a single stage and double stage condensing unit. The supplier of the single stage told me that if I can maintain my condensing unit ambient temperature at 32 C (considering the outdoor temperature to be 45 C) I will be able to obtain -30C in my chamber. However, the supplier of the double stage disagrees to this and mentioned a single stage can obtain a temperature of -22 C only, even if the ambient temperature where the condensing unit is placed is 32C and hence he offered me a two stage condensing unit. I need to know if the single stage condensing unit can obtain temperature of -30C and if its possible what are the modifications required to be done to it?? Please keep in mind that the chamber is small sized.

Thanks!

[mbc]

it is imposable( your outdoor is 45 c)so how you can down it to 32

I think you mistake. you should go to 2 stage compressor in -30 c.

what kind of compressor your going to use ?

[Magoo]

Hi Jency.
The two stage supplier would be concerned with the possible 45'C ambient. With a generously sized condensere and a 10 ' approach the condensing temp would be 55> 60'C +. Evaporating at -35'C and 60'C + conden temp., that could be outside most single stage compressors operating limits, even with oil cooler and head cooling