Cooling purity water without a exchanger.

[zhangbd]

Dears,

I have a problem with our 20C Purity water loop, in summer the water temperature of this loop is higher than 30C,under this temperature, you know, the risk of bio-fouling is high, however we don't want to install another exchanger to cooling the water temp. down, that would be a large expending. We think a cooling coil twisting around pipes maybe available.

Who could suppy me this or give any useful information.

Thanks&regards

zhangBD

 

[Cooky]

What is the pipe diameter & flow rate?, and what cooling capacity do you require?.

Personally, I am sceptical about wraping a cooling jacket around a pipe.

Cooky.

 

[SAK9]

You can go in for a pipe in pipe heat exchanger.The inner pipe will be your existing pipe.You need to do an outer pipe to circulate the cooling medium

 

[zhangbd]

Dear cooky and SAK9:

Yes you're right, I prefer to install a wrapping cooling jacket around the pipe to cool down the water temp.

The diameter is DN40, and the peak temperature in summer is 35C.

I have contacted some suppliers but they cannot provide us with this unit you mentioned, could you introduce some vendors for us?

Thanks

zhangBD

 

[SAK9]

You may try the link below to get some info on how to design a double pipe heat exchanger.You may then get this fabricated by your inhouse contractor.

http://www.mae.ncsu.edu/courses/mae412/gonzalez/Lecture 02 - Heat Exchangers.ppt.

 

[25362]

Depending on the humidity of your ambient air one could also consider a trombone indirect evaporative cooler.

 

[greg87]

I don't know anything about your system, but for many pure water systems the reason that the system temperature is increasing is due to the heat input from the recirculation pumps. Almost all the brake horsepower of your pumps is converted to heating the water (for recirculating systems). Unless you have very high turnover, the temp will increase until the rate of heat loss to ambient equals the heat gain from pumping. Since your pumps need to provide the head and flow for the worst case delivery requirements, the rest of the time they are providing more power then is necessary. Using a VFD on the pump motors, controlled by flow rate (or pressure) in the return line, would allow you to match the output to demand. You would not be heating the water as much, and you would also be saving energy.

 

[zhangbd]

Thanks SAK9 ,

but I couldn't open the link you gave. and you mentioned that double pipe exchanger, we also call it concentric tube exchanger, I think that would be a good solution to our problem.

Dear greg87,

Our existing distribution system pump purity water via a VDF pump, the setting point must keep the flow rate in loop at lease 6m3/hour above, therefore we ciouldn't avoid the pump from heating the purity water.

zhang bd