[BBeerme]

pecmsg:

or the condensing unit...................... Just what was available for free.

or the evaporator........................... Home made coil from free copper.

or the temperature............................. 0*F


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[BBeerme]

Isn't that how we start all of these sorts of projects . . . ?

Gotta start somewhere on that learning curve.

I wish I had this site when I was learning all this stuff. Probably would've been hard to believe some of the answers, but sooner or later it would've sunk in. All I had back in the day was printed material and a telephone.

 

[Want to Learn]

How far off base am I ???
Sounds like an Ice Bank beer cooler. A TXV sure would control the superheat better so that the compressor is protected. What size copper evap did you make 1/4, 3/8 ? Using a TXV would be a better way I would think to control superheat and get your full compressors output but sizing it might be hard. 18000 at 45 deg evap would be how much at low temp ?

 

[VTP99]

18000 at 45 deg evap would be how much at low temp ?

Somewhere in the 6000 btu/h range.

 

[jehanzeb]

The evaporator coil has OD of 1/2 inch, and total pipe length is 65 feet. The spacing between pipes is 4 inches so that around 2 inch thick ice can form on each copper pipe length. The straight pipe length is 2 feet and then a bend with elbows. The entire evaporator is 2 feet X 2 feet X 2 feet.
I agree that a TEV would be better, but I need to figure out how to put that in and replace the capillary. BTW the condenser is the standard one that came with the outdoor unit.

 

[icemeister]

The evaporator coil has OD of 1/2 inch, and total pipe length is 65 feet. The spacing between pipes is 4 inches so that around 2 inch thick ice can form on each copper pipe length. The straight pipe length is 2 feet and then a bend with elbows. The entire evaporator is 2 feet X 2 feet X 2 feet.
I agree that a TEV would be better, but I need to figure out how to put that in and replace the capillary. BTW the condenser is the standard one that came with the outdoor unit.

What is the purpose of this ice? Is is for thermal storage or something else?

Is the water in the tank agitated, recirculating or is it still? Bare tube evaporator tubing in still water has terrible heat transfer.

 

[jehanzeb]

What is the purpose of this ice? Is is for thermal storage or something else?

Is the water in the tank agitated, recirculating or is it still? Bare tube evaporator tubing in still water has terrible heat transfer.

Yes this is for thermal storage, as we have 5 hours per day of load shedding, so I plan to use the ice for cooling later. Right now the water is still but I am planning to put an aquarium pump for agitation.

 

[icemeister]

Yes this is for thermal storage, as we have 5 hours per day of load shedding, so I plan to use the ice for cooling later. Right now the water is still but I am planning to put an aquarium pump for agitation.

Load shedding...that's what I thought you might be doing.

Here's a website that may interest you: http://www.chester-jensen.com/ice-builder

 

[TechmanTerry]

How did you get 65' copper length? Is this evap made w/ 90* elbows? If yes, what radius ell's?

I'll take a SWAG and say that a 18k btu AC comp can be a Cope MN#-ZR18K5-pfv. Well, this comp can produce around 6000k btu ,around -10*F SST, around a 95*F SCT,which is about a 72-75*F ambient for the CU. Or around 10k btu @ 0*F SST. Not bad. But IDK about your comp.!??

 

[powell]

Hi Everyone,
Is there any way to drop the current evaporator temp of -2 C to -20C. Maybe My question is that how the suction pressure in a deep freezer is maintained around 10 PSI? What do I need to change in this system to drop the temperature?Tell us the compressor number
Jehanzeb

We need the compressor number!

 

[BBeerme]

Also be nice to know what type of container the evap and water is in. In particular, how well is it insulated?

 

[jehanzeb]

The compressor is Boyard (Chinese make), the website link is http://www.zjboyang.com/info/?113.html
and the closest model is QXR-30E, as the one I am using has been discontinued..

To answer the other questions- I am using a fiber glass tank with outside insulation with thermopore. The elbows are 90 degree bend, but dont know the radius.
Thank you Icemeister for the useful link.

The 65 feet copper tube was based on the fact that I will go for 1.5 inch thick ice and I need 120KGs of ice for around 2 hours of load shedding (at 18000 BTU per hour) so that make the pipe length to be 65 feet.

 

[powell]

The Boyard compressor you have is a rotary type. I cant find the performance charts on it.

The comparable Tecumseh model, RKA5518EX, will pump 6630 btuh @ -5F SST @ 110CT using R22.

 

[jehanzeb]

Thanks for the info. How about if I run at -10 C (14F)? I think I might make ice more quicker due to higher BTU? From what I understand I have to find the sweet spot temperature where I get max efficiency in terms of compressor and also in terms of heat transfer rates from R22 to water/ice

 

[powell]

Thanks for the info. How about if I run at -10 C (14F)? I think I might make ice more quicker due to higher BTU? From what I understand I have to find the sweet spot temperature where I get max efficiency in terms of compressor and also in terms of heat transfer rates from R22 to water/ice

10,500 btuh @ +15F SST @ 110F CT

Since you experimenting, just pick a rating and go for it. If it doesn't work, change something.

 

[icemeister]

Thanks for the info. How about if I run at -10 C (14F)? I think I might make ice more quicker due to higher BTU? From what I understand I have to find the sweet spot temperature where I get max efficiency in terms of compressor and also in terms of heat transfer rates from R22 to water/ice

Your "sweet spot", as you call it, will be determined by the balance of the capacity of the condensing unit to move heat and the capacity of the evaporator to absorb it.

You already know that a lower evaporator temperature will increase the capacity of the evaporator, however at the same time the capacity of the condensing unit is decreased. So the "sweet spot" is where the capacities are the same.

You experimentation will likely be focused on the evaporator because the condensing unit design is fixed. You can increase evaporator capacity by increasing the temperature difference between the water and the refrigerant, but it can also be increased (and more efficient) by increasing the water turbulence around the tubes or increasing the surface area of the tubes.

 

[BBeerme]

There's another factor that you need to consider. Ice in and of itself has an insulating factor. So, the thicker the ice on your evap tubing, the less heat transfer from the water through the tubing to the refrigerant.

Simply another reason that an expansion valve is a better choice for the metering device.

I just had an interesting thought. First off, I expect you're not going to get much pay back, as in ice being formed to do what you want. But, check this out . . .

What if you put salt in the water so the water would not freeze. Then you fill a bunch of small balloons with water and put them in the salt solution. Then freeze the balloons. There would be some corrosion of the copper over time, but you might have more heat transfer in the freezing and thawing process; you need surface area. Right now you are limited to the surface area of the tubing.

Just a thought.

Thanks for the info. How about if I run at -10 C (14F)? I think I might make ice more quicker due to higher BTU? From what I understand I have to find the sweet spot temperature where I get max efficiency in terms of compressor and also in terms of heat transfer rates from R22 to water/ice

 

[jehanzeb]

Thanks guys for your great help. I ll start with the experimentation to see the best ice making time. I ll put in a air pump as well for water agitation.
BTW BBeerme using salt water with balloons is a good idea, but I cannot use it as I am using the same water for the indoor fan coil unit, so rust issues would be critical specially for the indoor unit pipes.
I ll update this threat once I have conducted a few experiments.

 

[Are Gee Specht]

Any result? I'm very intersted in this project, working on the same project, homemade solar air conditioning using ice as a thermal battery.

 

[jehanzeb]

I dont have the results yet, as something is wrong with my outdoor unit, I think its a stuck valve or something. I am trying to debug that right now. BTW ARE Gee are you making this for load shedding or for solar? Which country are you from? As solar presents its own challenges - variable output of panels etc