Surface wetting of R22 vs Ammonia

[Michael Bellstedt]

I am looking for information on the relative performance of R22 and ammonia in film evaporators. As far as I know, R22 is more likely to wet a metal surface than ammonia, and hence should perform better when used on the outside of a tube bundle, eg. in spray recirculation (horisontal bundle) or film flow (vertical bundle). Can anyone point me in the right direction or send me some literature on the subject??

[Andy]

Hi, I think that NH3 would wet you surface and cause greater heat transfer than R22, mainly due to it's higher latent heat per Lb. Most spray chillers I have seen avertised have been NH3, this may be due to the chillers being pump circ which means an NH3 varient will have smaller pumps. Also R22 will mix with the oil NH3 won't if you use R22 a siginificant proportion of what you pump will be oil insulating the heat transfer surfaces and reducing the effectiveness of the heat exchanger. Whitt, a German company make spray chillers, you could try a search for them.
Regards. Andy.