Saturday, July 7, 2018

Custom made micro a/c

Hello everyone. I'm building a small, custom made a/c unit to cool an electronics cabinet. The electronics container sits remotely, far from people and sensitive electronics are inside. Long story short, I'm making a a/c that will cool about 300 watts of power to about 75F. The box is EXTREMELY insulated, we can assume no air goes in or out.

I'm Using a condensing unit like the one in this posting :

https://www.aliexpress.com/item/REKI-DC-Small-Cooling-Unit-for-Mini-Refrigerator-Freezer-RAF115DC24-V/32499056834.html?spm=a2g0s.9042311.0.0.4e7b4c4dtanktt

The Evap is about 80mm square, and has about 8 passes. Dont know how else to describe it. 100% copper.

I'm using R134.

After full assembly, I pulled a full vacuum for 1 hr, then waited and it held for 1 hr, then charge with gas. i ran some test. this is where the problem is. Its not cold enough. The Condenser does not feel hot, the evaporator blows "cool" air, but not cold, like a window a/c would.

I'm not really sure how much Refrigerant I put in it. These are the stats I got:

At Compressor MAX and Evap fan in medium air flow.

Condenser pressure= 1Mpa (145 psi), 43C~(109F)

Condenser outgoing liquid ( taken at end of dryer filter, where capillary begins) 100F

Evaporator pressure= 0.35Mpa (50.7 psi), 12C~(53f)

Evaporator outgoing gas ( about 1 inch of pipe out of evap) 64.6F

Ambient air=82F

Incoming air to Evap =82

Air coming out of Evap= 73~74.5F

I believe my capillary is too short. Anyone got any ideas to increase superheat and supercool?

submitted by /u/Some_Awesome_dude
[link] [comments]

No comments:

Post a Comment