Plate HX presure reading

MeltedDuron · 10-08-2009, 12:39 AM

Can you take a presure reading from a plate HX (directly off the HX). Some length of cap tube from it to a manometer? So say you have 5 stages, at each stage you can see what the presure at the HX is? This is on it's own and not to do with the system high and low

Patrickclouds · 10-08-2009, 03:30 AM

you can messure the pressure before and after the plate hx. so you know exactly your pressure loss.
so you only have the chance to place a manometer on inlet or outlet. i think it would be difficult or impossible to messure the pressure between the plates.

MeltedDuron · 10-08-2009, 08:10 AM

Quote:

Originally Posted by Patrickclouds

you can messure the pressure before and after the plate hx. so you know exactly your pressure loss.
so you only have the chance to place a manometer on inlet or outlet. i think it would be difficult or impossible to messure the pressure between the plates.

Would there be much presure lose between the inlet and outlet? Im guessing you mean im to fit the manometer on the inlet and outlet of the same system ie 1st stage? If so the presures there would be different to the high and low side right? Im thinking of having a super pimped HX stage with lots of info and data on show.

Plate HX temp (stage temp/evap temp)
Inlet temp (both 1stage and 2nd stage)
Outlet temp (both 1stage and 2nd stage)
Low side presure
High side presure
Inlet presure (both 1stage and 2nd stage)
Outlet presure (both 1stage and 2nd stage)

Thus showing the behavour of the refrigerant as it's boiling off in the system. Plus it'll just make it look more confusing to anyone whom has no idea of these systems

Patrickclouds · 10-08-2009, 11:20 AM

Quote:

Originally Posted by MeltedDuron

Would there be much presure lose between the inlet and outlet?

that depends on how big and strong the compressor is and how small you´ve choosen the hx. you should be sure that the hx allows enough massflow. so there will be now pressure loss.

Quote:

Originally Posted by MeltedDuron

Im guessing you mean im to fit the manometer on the inlet and outlet of the same system ie 1st stage? If so the presures there would be different to the high and low side right?

yes manometer on inlet and outlet of the 1st stage. but think of it the inlet is low side and the outlet is also low side

the refrigerant evaporates bevore hx inlet

if you have copper pipe with enough diameter ther shuold be no pressure difference between outlet und suction line.

i think that you don´t need all those manometers if you choose the right hx for your compressor and the right diameter of the copper pipes.

MeltedDuron · 10-08-2009, 02:55 PM

Quote:

Originally Posted by Patrickclouds

that depends on how big and strong the compressor is and how small you´ve choosen the hx. you should be sure that the hx allows enough massflow. so there will be now pressure loss.

12,000 BTU Toshiba PG180X1T-4CZ 1PH 230v was gased with R407c in a upright portable ac unit. HX i think will be 12 plate.

Quote:

Originally Posted by Patrickclouds

yes manometer on inlet and outlet of the 1st stage. but think of it the inlet is low side and the outlet is also low side

the refrigerant evaporates bevore hx inlet

if you have copper pipe with enough diameter ther shuold be no pressure difference between outlet und suction line.

i think that you don´t need all those manometers if you choose the right hx for your compressor and the right diameter of the copper pipes.

I though it would of ecaporated within the HX hense the cooling down part. So there should be a difference really with it boiling off.

The reason for the manometers is just to show off the tech side of it and also see whats going on and all the differences.

tiborrr · 10-08-2009, 05:08 PM

You're taking on auto-cascade? Good lucky buddy! And don't feel too dissapointed if it doesn't go right the first time.

MeltedDuron · 10-09-2009, 02:32 AM

Quote:

Originally Posted by tiborrr

You're taking on auto-cascade? Good lucky buddy! And don't feel too dissapointed if it doesn't go right the first time.

Really not sure what to do. Have a few parts to do ether an auto or a casacde. Don't have everything for ether but i have enough to make a start on ether one of them.

2 X 12,000 BTU's rotary
1 X 30,000 BTU scroll
4kw STV Lvfe condesner
Danfoss & Ranco HP switch
Danfoss shutoff valve
Tes 2 x2
TEX (R22) X2
HX boxes
Poitres suctione line 120cm and evap
4 bottles of R600a
1 bottle of R404a
1 tank of C02 (food grade)

Im just toying with the ideals of having as much info on show for each stage to show off sorta thing

tiborrr · 10-09-2009, 03:39 AM

Start with cascade, it's still one step easier than auto-cascade. You may strip it apart later and make it into auto-c. I was very frustrated with getting the right charge (ironically, I got the cap tubing right) of refrigerants in the system. Eventually it payed off.

Keeping fingers crossed for you, buddy!

Best Regards,
Niko

MeltedDuron · 10-09-2009, 03:47 AM

Quote:

Originally Posted by tiborrr

Start with cascade, it's still one step easier than auto-cascade. You may strip it apart later and make it into auto-c. I was very frustrated with getting the right charge (ironically, I got the cap tubing right) of refrigerants in the system. Eventually it payed off.

Keeping fingers crossed for you, buddy!

Best Regards,
Niko

I have a mate whom has some R1150 going cheap. I just need pipe work, oil sep. Im really not sure what to do at all.

I guess i could start off with a single stage sort of that could also be used a water chiller which is then lead to a 1st stage in a cascade.

So do i use the 30,000 for a super strong base or the 12,000

tiborrr · 10-09-2009, 04:10 AM

12k BTU + 12k BTU makes for a very powerful cascade, 30k BTU would be a waste in a 2-stage cascade cooler. Perhaps for a powerful 3-stage.

Start off easy, step by step & learn as you advance. Be safe & have fun, buddy!

MeltedDuron · 10-09-2009, 07:46 AM

Then i might as well go 30K and 12K BTU then i can add the other 12K BTU at a latter date for a 3 stager unless i use the 30K for an auto c.

wdrzal · 10-09-2009, 08:30 PM

Quote:

Originally Posted by Patrickclouds

you can messure the pressure before and after the plate hx. so you know exactly your pressure loss.
so you only have the chance to place a manometer on inlet or outlet. i think it would be difficult or impossible to messure the pressure between the plates.

If you want to do the calculations:

http://scienceworld.wolfram.com/phys...eltNumber.html