Plate Heat Exchagers - Condenser

[Billy Ray]

Plate Heat Exchangers for Condenser Purpose?

Thoughts / Suggestions / Required Please - - -

When applying a plate heat exchanger as a condenser, what considerations are required?

The application is medium temperature (+4 Cold Room).

The condenser is a plate heat exchanger, which is connected to a central building systems evaporative cooling tower. The condenser receives water at typically +25 deg C (this dependant on the ambient).

All thoughts & suggestions on configuration are wellcome, more particular is the requirement for a liquid receiver?

Note: The liquid main length is 1 meter (water cooled condening unit positioned above cold room).

Billy Ray

[Lowrider]

Right or wrong place, doesn't matter to me!

I work on a lot of chillers with water cooled condensors using either a PHE or shell and tube.

The big advantage of a PHE is the smaller space needed compared to a shell and tube in the smaller chillers.

In the scroll chillers we use PHE's, in the larger chillers (screw and centrifugals) we use shell and tube because here a phe would be larger than a shell and tube.

Hope I explained it clearly!

The need to control the entering water temperature remains the same for each condensor.

[Billy Ray]

Lowerider,

do you regonise a need for a liquid receiver when utilizing a PHE?

in contary, a shell & tube condenser can be considered as a combined condenser/receiver!

Billy Ray

[Lowrider]

That all depends what type of system you use.

It depends on how much you'll have to buffer. In a phe the amount you can buffer is smaller than in a shell and tube.

On our chillers we only use a buffer if it's a heat pump, not when it's a chiller.

If you have a cold store with multiple evaps than the need for a buffer will be bigger than on the chillers we build. You'llhave to calculate the amount of refrigerant circulating at full load and at the lowest load and size the buffer to match the difference.

[monkey spanners]

Also if its on pumpdown control you will need enough storage capacity for it to pumpdown fully.

Jon

[US Iceman]

Since the volume of the PHE is a lot lower than the shell & tube you will probably need a receiver because of the pump down cycle and longer line lengths in a cold store.

The requirements for a PHE are the same as for a shell & tube exchanger. You just select the PHE for the heat rejection requirements, water flow rates (or water temperatures IN & OUT, which will determine the flow rate for the heat rejection necassary), condensing temperature desired, etc.

[powell]

I'll add that a brazed PHE is more difficult to clean versus a shell and tube. Keep the water clean.

[Lowrider]

I'll add that a brazed PHE is more difficult to clean versus a shell and tube. Keep the water clean.

You're right! That's why we always say the water circuit has to be be flushed a couple of times after installation and there has to be a filter included!

[Billy Ray]

Any suggestion for filter basket size?

500 micron / 1000 micron?

'Too small' i would suggest would continually block, bearing in mind if the system was hooked up to an evaporative tower on a central system, maybe not so much if connected to a dry cooler!

'Too big' would not protect!

Billy Ray

[US Iceman]

Or, you can use a centrifugal separator with a blow down cycle. No filters to clean and it's automatic.