Chilled Water/Refrigerant Flow rate

[schiZ0prEni]

Hye all,

I would like to know how to calculate the capacity (Q = m X c X delta T ) if the flow rate of the refrigerant or chilled water can not be determined?Any suggestion or thought are much appreciated!

ThanX!

[mad fridgie]

Very strange question,
I presume that this is an existing installation?
If so check your refrigerant pressures , temps and current.
transpose against compressor manufactures data. Duty.
Then check your TD across the evap on the water side, do the calcs using the the comp duty, to give water flow.
If water is pumped check pump pressures and current against manufactures data, to back up water flow rate.

[schiZ0prEni]

sorry the question not in detail..
yeah,this is an existing chiller system where they not installed any flow metering device at the pipeline,so i could not check the flow rate of chilled water..

actually,i wanted to do energy assesment of the chiller. I need to calculate it's performance (actual) and compare with the design condition.

since there is no way of getting the flowrate of the chilled water,maybe there are some other ideas or assumption can be made like assumming the actual flowrate is same with the design flow rate.

BTW,thanks Mad Fridgie for the reply!

[mad fridgie]

sorry the question not in detail..
yeah,this is an existing chiller system where they not installed any flow metering device at the pipeline,so i could not check the flow rate of chilled water..

actually,i wanted to do energy assesment of the chiller. I need to calculate it's performance (actual) and compare with the design condition.

since there is no way of getting the flowrate of the chilled water,maybe there are some other ideas or assumption can be made like assumming the actual flowrate is same with the design flow rate.

BTW,thanks Mad Fridgie for the reply!
You can purchase (hire) a non contact flow meter
This could give actual flows.

[Brian_UK]

Or, if the machine can be stopped and partially stripped, you could check the duty of the expansion valve.

[Andy]

sorry the question not in detail..
yeah,this is an existing chiller system where they not installed any flow metering device at the pipeline,so i could not check the flow rate of chilled water..

actually,i wanted to do energy assesment of the chiller. I need to calculate it's performance (actual) and compare with the design condition.

since there is no way of getting the flowrate of the chilled water,maybe there are some other ideas or assumption can be made like assumming the actual flowrate is same with the design flow rate.

BTW,thanks Mad Fridgie for the reply!


Hello:)

you could hire out an ultrasonic flow meter and measure the flow without breaking into the system, or break into the system a fit a flow meter.

Kind Regards Andy:)

[Lowrider]

Get the chiller running in full load.
Make sure its running as near as possible to the design setpoint and than just fill in the data you have into the formula. Take 4.18 kj/kg for water, the measured dT across the evaporator and the design capacity in kW. You can calculate the flow rate in l/s!

[Peter_1]

Take AMP readings and at the same time DP over the pump and look in the pump chart to determine flow.

[Peter_1]

Andy, you don't have to brake in physical in the pipes?
Is the material of the pipe important in this measurement?

[Brian_UK]

Peter, you can normally use them on most pipe types, they depend on the water being slightly dirty.

I've used them in the past quite successfully.

See some models here....
http://www.rshydro.co.uk/Portable-c-321.html

[Peter_1]

I always thought you had to make at least 2 holes in the tube. I could have use those in the past where I had some cases where flow needed to be measured.
I already searched yesterday on the net and I found interesting information.
Learned again something here. Thanks

[Grizzly]

I always thought you had to make at least 2 holes in the tube. I could have use those in the past where I had some cases where flow needed to be measured.
I already searched yesterday on the net and I found interesting information.
Learned again something here. Thanks

Peter.
It's true isn't it that we never know it all.
May I just add to the excellent info the guys have already given you.
That the larger ones we sometimes use, have a programmable setting.
Where you select the material the pipe is made from.
The ones we have are so expensive that they are normally "shared" across several depots.
Because we have Marine Guys we have been known to borrow theirs!
cheers Grizzly

[Andy]

Andy, you don't have to brake in physical in the pipes?
Is the material of the pipe important in this measurement?

Hi Peter:)
I can see i've been beaten to the answers:D

Being tight I normally don't use then, prefering to use the pump curves.
I have now opted to use either an oriface plate or a double regulating valve with manometer connections on all new chilled water jobs. Yet to buy a differential pressure manometer, but we can hire one.

Kind Regards Andy:)

[pnkrishna08]

hi..i need cooling load formulae