How to maximise chiller efficiency

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?

[BarraCuda™]

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

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.

[BarraCuda™]

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.

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.

[BarraCuda™]

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.

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.

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.

[BarraCuda™]

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.

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.

[BarraCuda™]

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?