Arofanatics Fish Talk Forums  

Go Back   Arofanatics Fish Talk Forums > General Aquatic Forums > AroReefers > Articles, Resources & FAQs

Reply
 
Thread Tools Display Modes
Old 26-04-2005, 12:51 AM   #11
monsterz1975
Guest
 
Posts: n/a
Default

I was told to use a lower flow pump for my RR1.25hp by an expert who is making chiller for LFS. And i seen PR is using a low flow pump for their 1.25hp RR chiller too. So how should i go about?
  Reply With Quote
Old 26-04-2005, 01:03 AM   #12
BarraCuda™
SiaoGu Gives You Wings
 
BarraCuda™'s Avatar
 
Join Date: Jul 2001
Posts: 4,169
Default

Quote:
Originally Posted by monsterz1975
I was told to use a lower flow pump for my RR1.25hp by an expert who is making chiller for LFS. And i seen PR is using a low flow pump for their 1.25hp RR chiller too. So how should i go about?
I'm also aware of this low flow guideline, however I never managed to find out why the chiller need low flow. If the expert can explain the thermodynamics why having a low flow is better, maybe I can understand better.

All these are not theory only, I personally changed the hose size from 1/2" to 1" and I have seen the difference in reduction of chilling time. I would still say, dont take my words for it, go and try out!

Maybe I quote another example.

You drop 2 cubes of ice in 2 cups. 1 is 100C, 1 is 50C. After the ice have melted, which cup will have the greatest reduction in temperature? Of course cup 1.

Its because "coldness" is always referred to a reference pt. Ice is very cold to hot coffee but ice is very hot to liquid nitrogen. The greater the temperature difference between the water and Ti coil, the better the heat transfer.

If the flowrate is too slow, the actual temperature inside the heat exchanger is much lower than the tank water temperature thus narrowing down the temperature difference
BarraCuda™ is offline   Reply With Quote
Old 26-04-2005, 01:10 AM   #13
monsterz1975
Guest
 
Posts: n/a
Default

Quote:
Originally Posted by BarraCuda™
I'm also aware of this low flow guideline, however I never managed to find out why the chiller need low flow. If the expert can explain the thermodynamics why having a low flow is better, maybe I can understand better.

All these are not theory only, I personally changed the hose size from 1/2" to 1" and I have seen the difference in reduction of chilling time. I would still say, dont take my words for it, go and try out!
Try out liao . lowflow chill the tank faster but cut in also faster.
  Reply With Quote
Old 26-04-2005, 01:14 AM   #14
BarraCuda™
SiaoGu Gives You Wings
 
BarraCuda™'s Avatar
 
Join Date: Jul 2001
Posts: 4,169
Default

Quote:
Originally Posted by monsterz1975
Try out liao . lowflow chill the tank faster but cut in also faster.
What is the cut in duration after the compressor stopped for both high flow & low flow.
BarraCuda™ is offline   Reply With Quote
Old 26-04-2005, 01:21 AM   #15
monsterz1975
Guest
 
Posts: n/a
Default

Quote:
Originally Posted by BarraCuda™
What is the cut in duration after the compressor stopped for both high flow & low flow.
Different of 1/2 to 1 hr.
  Reply With Quote
Old 26-04-2005, 01:31 AM   #16
BarraCuda™
SiaoGu Gives You Wings
 
BarraCuda™'s Avatar
 
Join Date: Jul 2001
Posts: 4,169
Default

Quote:
Originally Posted by monsterz1975
Different of 1/2 to 1 hr.
Check the temperature of the between chiller and tank water. If you are using low flow, you should get a lower reading of abt 2C from the tank water.

Quote:
Compressor workcycle
If the flowrate is slow, you risk the temperature probe registering a false reading. This will cause the chiller to start/stop regularly, sometimes 4-5 times/hr. E.g if the water do not leave the heat exchanger fast enough before the reaching the preset temperature, the chiller will sense that the water is chilled thus shutting down the compressor. When warm water from the tank gradually replaced the chilled water, the chiller will again start the compressor because now the water is warmer than the preset temperature!
The temperature probe may be registering a false reading that the preset temperature is already reached. When the water temperature equalised, the water temperature is higher than the preset temperature. Thats why the chiller "chills faster".

Whereas the higher flowrate managed to reached a temperature closer to yr tank temperature. That explains why it takes longer to chill and heat as well.
BarraCuda™ is offline   Reply With Quote
Old 26-04-2005, 01:36 AM   #17
monsterz1975
Guest
 
Posts: n/a
Default

Quote:
Originally Posted by BarraCuda™
Check the temperature of the between chiller and tank water. If you are using low flow, you should get a lower reading of abt 2C from the tank water.



The temperature probe may be registering a false reading that the preset temperature is already reached. When the water temperature equalised, the water temperature is higher than the preset temperature. Thats why the chiller "chills faster".

Whereas the higher flowrate managed to reached a temperature closer to yr tank temperature. That explains why it takes longer to chill and heat as well.
Ok i go try with higher flow again.
  Reply With Quote
Old 26-04-2005, 01:38 AM   #18
BarraCuda™
SiaoGu Gives You Wings
 
BarraCuda™'s Avatar
 
Join Date: Jul 2001
Posts: 4,169
Default

Quote:
Originally Posted by monsterz1975
Ok i go try with higher flow again.
Very simple lah. Take a accurate lab thermometer, measure the tank water temperature when the chiller stops. The temperature should be higher than the preset temperature.
BarraCuda™ is offline   Reply With Quote
Old 26-04-2005, 01:50 AM   #19
monsterz1975
Guest
 
Posts: n/a
Default

Quote:
Originally Posted by BarraCuda™
Very simple lah. Take a accurate lab thermometer, measure the tank water temperature when the chiller stops. The temperature should be higher than the preset temperature.
When my chiller stop ,the temp from my chiller reading is different is 0.8deg highest that mean my set lowest is 26.2 and chiller cut in 27. My tank temp is the same as my chiller when it running but the different is when the chiller stop and the temp reading from my tank when my chiller start to cut in is 27.8deg. Sorry for my poor english. Never go school mah.
  Reply With Quote
Old 26-04-2005, 01:58 AM   #20
BarraCuda™
SiaoGu Gives You Wings
 
BarraCuda™'s Avatar
 
Join Date: Jul 2001
Posts: 4,169
Default

Quote:
Originally Posted by monsterz1975
When my chiller stop ,the temp from my chiller reading is different is 0.8deg highest that mean my set lowest is 26.2 and chiller cut in 27. My tank temp is the same as my chiller when it running but the different is when the chiller stop and the temp reading from my tank when my chiller start to cut in is 27.8deg. Sorry for my poor english. Never go school mah.
so the temperature difference is 27.8 - 27 = 0.8C?

What about the temperature of the high flow? btw how much L/hr is yr low and high flow? Using 0.5" or 3/4" pipe?
BarraCuda™ is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +9. The time now is 09:58 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Copyright © 2000-2008 Arofanatics.com (Since 30th August 2000)