Gases

[100]

OK, I have put a LOT of my time into thinking about the best (or better) refrigerant mix (zeo), to better or at least compete with R22's efficiency and heat load capacity.

I have come up with:

A 3:1 mix of

R410A : R143a

R410a has about 1.64x the pressure of R22. I chose 143a over 407c because it is so cheap, and is perhaps could be a very effective 'filler' (saving a 1/3 on cost).

As I understand it, R410a is less environmentally depletive than R22, but is about 9x more expensive. (£1.30 per Kg, compared to £11.60 per Kg) so I am yet to make up my mind on whether to go for R404a (a rather more comfortable 5.40 per Kg).

Using a lo-bp comp @ 0.31kw, I'll experiment with this mix over the next few weeks and see if it is as good as I hope it will be.

I'm buying a recovery unit for this project to save on my outgoings (r410a is a hefty on the pocket kinda gas). The hunt for the best single-subcooler system (not cascade) gas mix.

Feel free to flame me for being so stupid to step out of the bounds of just using stock gases r410a/r407c/r404a :D

What mix do you use, or perhaps contemplated?

[JSU]

um why dont you just use r507 or r404a straight? O add alittle propane to them?

[Pandrone]

Sounds to me he wants the lowest temps possible with just one stage?. If so i'd try R13B1 and that with a big compressor :).

[HawainPanda]

R13B1, never heard of that, how low can that get u? and at wat pressures? but, if wanted the lowest temps, just going with r507 would get u prob the lowest u can get wouldn't it?

[Pandrone]

R13B1 also called Halon 1301 (used in old fire-extinguishers). Bolingpoint is -58c if i remember correct @ atmospheric pressure.

[HawainPanda]

whoa...old fire extinguishers...i have one of those... ;P excellent

[Pandrone]

Not all fire-extinguishers that is. Only those used for protecting valuable (electrical?) equipment i think. In sweden it's still used in boats and computerrooms etc. It's a CFC so it's banned from use in Europe, in US too if i'm not mistaken.

[chilly1]

13b1 is on the list.

[bh2k]

The "list"

[blinky]

Originally posted by pc ice
schindler's list.?

J/K dont make me get my jew homies and woop u

:D

[JSU]

wow that sounds like a realy good gas to use psig is right around the same area (alittle higher) as r507. Has anyne tried it?

[100]

@i would like somthing withalittle less psi than r410 but with -60c boiling point.

Hi Pc-Ice, r404a is near to there, r402a (restaurant ice-maker machines use this) is a little nearer to your specs, r409a is also a viable choice. In my short experience (9 weeks learning about HVAC and Refrigerants), R403B is a VERY good choice for this job, however cost (£21/kg) and pressure (8psig@-60), keep me from using this.

Reggie, what is R13B? I cannot find data materials on it, and I don't think it is legal (if it aint HFC, I cant get it). Any datasheets on it? (All my fire extinguishers are foam and co2 ^^)

I am just taking this opportunity to everyone who has replied to this, thank you very much!

I have established with a Copeland 350w lbp, using r410a (filled up to level where :

410a = 180psi, evap temp = -40 (suc/li temp -22 with 100w pelt)
r410a +r404a = 206psi, evap temp = -44 (suc/li temp -23 with 100w pelt)

A very small amount of r404a made a lot of difference.

Internal volume of entire system including compressor is 25.4cm^3 (according to my reading+filling of dry nitrogen).

I am still to plot more results on a graph. Will report back to you guys later with a (hopefully) nice curve, which can be interpolated to give the best pressure at which the r410a lies where the rest can be topped-up the system with r404a.

Anyone think what I'm doing is stupid?

BTW, I am using a simple 2-line maze for evap, [single story evap], obviously a baker block would be _a lot_ better or maybe if I invested more time in it. But I'm only looking at gases right now :)

BTW, Seperator on suction line reports 170psi(! ). I am not straining compressor?

In the next week I will CNC myself a better block, in the meantime it is just gas research.

[100]

mmm precious r408a mmm.
Kinda cheap too, http://www.rabtherm.co.uk/products.html
I'm sure I'll be able to find a cheaper one through my trade contacts.

[Redwolf]

My listing for 403b doesn't show it going that low. Its a mix of 290/22/218 5%/56%/39%
@ 0psig -43.8C -46.8F


Could try a pressure reducing valve (CPR) to compinsate for the higher pressure when your oil seperator purges.

[100]

Redwolf, I bought myself a 1Kg sample carton and it is not a practical price for the amount. It has delivered a better temp on suction line than the rest of the gases, so I just 'shot my mouth off' when I referred to it. I have also tried R404A and R410A, but my best results were with R403B, I probably did something wrong though, (or bad calibration?). -26 sucline temp, (pure r403b).

I have all the equipment except a recovery unit (I have another compressor which I attach to valve, discharging into second system, this is only a temporary measure). I have to use my current discharge system as I am not allowed to discharge them into the air by EEC Law.

Thanks very much for the CPR advice, I'll look into pricing (shouldn't be more than £10), that isn't a big priority at the moment. Could I ship the entire system over to a 2/3 hp comp; getting better suction, reducing gas pressure hence removing pressure from the sep/cl unit? I'm probably compleeetely wrong there.

[kayl]

what about r290/r404a/r410
that sould be an ok mix for single stage and nice temps
not sure on mix percent though

[100]

I'd get a bottle of R404a, charge up my system to 150psi, stick in a little more r23 to 180 and top it up with r410a.

Remember; R404A Has the Best Vapour SHC of all med.temp refrigeration HFCs.

I buy solvay gases and I'm looking at their catalogue right now for 404a; solkane 404a (standard r404a) has the pretty much the same PTC as 507 ^^, and is ozone friendly.

Won't be using propane because I work in a non-spark-free zone ^^