Chiller selection

[Ambrish_bajpai]

Hi!

I want to cool the water from 34 degree centigrate to 10 deg centigrate and i want to use flooded chiller for the same. Some body told me that flooded chiller shall not be used for this application. Due to space constraint , i cannot use multiple chiller option . Can any body suggest some solution?? I want to use shell and tube type heat exchanger only .Will it work and if not why??

Refrigerant is ammonia and condensing temperature is 42 degree centigrate.

[PVA]

Dear Ambrish_bajpai,

We have experience in using flooded chiller for cooling water, but the main problem for this system is freezing of water in heat exchanger, so you must make strict control system (temperature of water) and system of quick giving hot gas in the heat exchanger. So, thereby you will work without any problem and you will have good result.

[charlie n]

With proper control, flooded ammonia is the most efficient way to cool this water. You may want to consider PHE as they are generally more efficient, much smaller and hold far lower refrigerant charge.

[GBRD]

Hi Ambrish,

As suggested above, use PHE type flooded chiller & you will be right. However, your requirement is for 10 deg C, but use good flow & temperature sensors to avoid freezing. I would recommend Alfa Laval PHE or cheaper one available @ www.idmc.coop (http://www.idmc.coop)

cheers
Gaurav

[charlie n]

If you decide to use a PHE, install a water pressure differential switch for freeze protection. When a PHE begins to freeze, the outlet water temperature goes up a little so a freeze 'stat doesn't work well but the pressure drop increases dramatically which makes a pressure differential switch relaible and workable as freeze protection.

[TXiceman]

10 degC is not difficult to achieve in a heat exchanger without freezing. Any good design should include a low flow sensor to protect the chiller as a well as a low evaporator pressure device.

Th biggest problem is the excessively high inlet temperature of the water. With a flooded chiller design, you can have problems with a high heat flux at the entry pass(es) of the chiller. This can lead to liquid distribution problems in a flooded design. An extremely high boiling rate will cause extreme turbulence on one end of the chiller.

When you have such a high entrance temperature, consider a plate exchanger design or possibly a DX design if it is small enough. Another solution is to use a run-around loop and a blending valve to blend with the high temp water so that the evaporator will not see such high temperatures.

Ken

[Tycho]

how much water do you need to chill?

and I would rather go with a spray chiller with NH3 instead of a flooded chiller, but that all depends on the space you have available

[enerji1]

Dear Ambrish_bajpai,

I read your thread newly. The sama invstement is planning to our process.
1600 ton/h water will be cooled form 32C to 16C.
Can you transfer your exprience if you made this system for your process ?

[priti]

Alfa laval/ swep/ tranter or equivalent phe chillers are good enough for this application.

But

danfoss/ hansen/ manik make epr valves are a must for safer & efficient operation.

Regards.

Priti