Lets say there is an airflow

its velocity : 0.59 m/s

area of flow : 0.13m^2

relative humidity measured : 33.5 %

temp : 22 C

I could calculate

X= 1g(h2o)/180g(dry air)

formula i found here on page 10.

I could also calculate

AH=6.3 g/m3

mass flow equation is : m=ϱ*A*v

the AH has the same unit as ϱ. Calculating as m=AH*A*v , i get 1.76 kg/h, which seems legit.

But is there a way to calculate "

like i tried putting the X in the equation like

Thanks for help! ]]>

IIAR Bulletin on NH3 piping seletion or pipe sizing calculation.

Hope the selection calculation would be in SI units. ]]>

For a week I'm surfing internet to find a specific heat of yogurt.

There are specific heat of most of dairy products, milk , foods and ….. but I didn't find specific heat of Yogurt.

Do any friends have source to read this parameter on it ?

Thanks for your help in advance.

Sincerely yours. ]]>

I'm studying about 2 stage cycle with NH3 refrigerant, and i don't understand some vital part about the whole thing.

I was told, that in an ice cream factory cooling tunnel there is like -40C, and to achieve that, they do the NH3 evaporation at around -45C , 0.4 bar , and the condensation is at around 40C , 10bar . ( between the 2 compressors, there is -10C and 2 bar)

But i checked the NH3 logP-h diagram ,or the diagram in CoolPack program and found that it doesn't even show the 0.4 , -45 bar part, like its on the edge of the diagram and those values are rarely used.

So maybe I'm understanding something wrong, and the evaporation isn't at isobar P=0.4 bar, isoterm -45C , or why is the diagram usually always show the part above 0.5 bar?

Thanks for the answers!

I have tried other forums for this cooler and the residential said to go to the commercial forums because I am using a 1/3hp compressor and the system is too large. The commercial forums tell me its too small and to go to the residential forums. Please help I am ready to shoot this thing.

Here is what I am trying to do. I have taken a 12CF chest freezer and installed a STC 1000 Digital controller in it to turn it in to a large refrigerator. Inside my modified freezer I am storing four 5 gallon kegs of home made beer at a temp of 35.5 degrees f. There is no problem with this part.

Here is the core problem.

On the lid I drilled a hole and put in a 4 faucet beer tower with the lines running down inside the refrigerator to the kegs. When I pull the beer from the tanks it gains heat from the tower and starts foaming like hell. On a 12 oz pour the temp of the beer climbs from 35.5F to 45 degrees F. So I am gaining 10 degrees, on successive pours it climbs to 42 degrees F so the tower cools down by 3 degrees on the second and third pour.

So I know that the metal of the tower is absorbing heat from the ambient temp of 90 degrees F. I have calculated that the brass in the tower retains 97 BTU's/hour ( I can show my metallurgical math if you desire).

The towers surface is 1.72 square feet yellow brass absorbs heat at 67 BTU's/ hr so if we take the surface area of the tower and multiply by 67. The surface of the tower is absorbing heat at 115 BTU's from the air per hour. (67.0 Btu Â· ft/(hr Â· ft2 Â·Â°F) @ 68 F) Both Perlick and Micromatic seem to agree with this number based on 4 faucets they say heat load of 25btu per faucet. my unit is also a 4 faucet. erroring on the extream side of caution, 115 BTU's from the tower, and another 100 btu for the faucets.

Now the beer that runs thru the lines is at 35.5 degrees. I think I need to get the beer tower down to 32 degrees F. to prevent foaming for a proper pour at 35degrees F. So if I did my math correctly, 8.33lbs (weight of water/beer) X 3 degrees X 60gph = 1499 BTU/hour

So if I did my heat load correctly I have static heat load of 312 BTU's without any beer being dispensed. With beer being dispensed I have a heat load of 1811 BTU/Hour.

So to solve this problem (the beer tower is equipped with glycol cooling lines) to cool of the tower and the product. I have built a glycol cooler.

I purchased a 1/3 hp danfoss 103g5880 compressor that has a btu rating of 2555 btu's/hr @ 30 degrees F using lbp/hbp (what ever that does, low back pressure high back pressure)

I have purchased a commercial condensing unit that is rated for 2800 btu's that has a cooling fan that is adjustable speed.

I have taken 50' of 3/8 copper tube and made a double coil to use as my evaporator in my glycol bath. The glycol bath is 2.5 gallons circulated thru a Procor rotary vane glycol pump pushing 80 gph.

So to cool the glycol bath down from ambient temp my initial static heat load (no pumps on no product thru lines) from 90 degrees to 30 degrees is 60 degrees X 8.3lbs X 2.5 gallons = 1245 btu's hr.

Perlick says that an additional heat load for the lines is 25btu/yard (assuming it was carring a product line which mine is not, but I add it to be on the safe side), I have 2 yards going to and 2 yards coming from the tower. so 4X25=100 BTU + 1811 btu before, so now my total heat load is at 1911 btu's/hr

Once the bath is cold and the tower is working the heat load will then be at 1911 btu's/hr. so the compressor should be running at 75% or running for 45min/hr.

So the compressor should be able to handle the 1245btu initial cooling of the glycol without the pumps,

then the 315 cooling if the glycol pump is running,

and the 1596 btu's when the beer is running thru the lines.

Now With my current set up I can get the glycol down to 32 degrees F but it takes about 3 hours to cool the bath. where by my calculations it should take only 30 minutes.

Once I turn on the glycol pump on to cool just the tower without beer, the bath jumps from 32 degrees to 48 degrees F and will not come down. Which I find is very strange since the heat load is only 315 btu's only 1/10 the btu's rated for the compressor.

I know that the diameter of the copper tube for the evaporator affects the heat absorption, and speeds used for cooling. is 3/8 X 50' too long or too small diameter?

I am also using a TXV inplace of the cap tube to make the unit more efficient. The TXV is of appropriate size and the orifice is also of correct size. The other problem is that with my current set up, the compressor gets HOT, hotter than I feel comfortable touching for more than a moment.

Can you please help me sort this out step by step starting with verifying the math in the heat load calcs. I am attaching photos of how I have set up the system.

P_20170912_204828.jpg

Please help me out I am loosing my mind, thus far it has cost over $800 to build this with the pumps and trying to get it all up and working. Please any help will be greatly appreciated.

Retired for some years now....410a heatpump split which I am now familiar with somewhat thanks to the manual. Anyway a quick question on a Lennox 2.5 ton unit of one of my neighbors. I've been trying to monitor this for as much info as possible. The lockout goes active after 5 low pressure incidents. Pressures look good. They leave for the summer to go up north leaving the AC on about 80°. I check out side and the can tell the units been running. Okay so, new house, they already replaced the evap and DC fan on this thing? (I fail to see any savings here from efficiency). I replaced the board, relatively cheap. Talked to one of the techs that serviced this thing and he never got back to me. Okay so here's the problem. Unit goes into low pressure lockout however, all summer being it's left on cooling it's fine....that's what I know up to this point. I suspect the change over from heat back to cool has something to do with it. Just wondering if the reversing valve somehow could cause this? I can never catch a low pressure situation, the unit may operate for weeks or a month before this happens in the winter. In Florida we use heat but can quickly need cooling some warmer days in winter. Any thoughts? ]]>

And dont think Ive come across a thermal-electric expansion valve before, where they used much before electronic valves came in use?

Thanks ]]>