AC Precooler

 Premier Industries, Inc.


GENERAL:  Precoolers are evaporative cooling modules that are used specifically to precool air  that is used to cool equipment such as heat exchangers, etc..  Perhaps the best example of how a precooler is used is the conventional air conditioner condenser coil.

     This coil is used to dissipate heat to the outside air during the cooling cycle of the air conditioner.  Without precooling, the condenser coil uses outside air to dissipate the heat.  If that heat is 120 degrees (f) then the efficiency of the heat transfer is greatly reduced.  With precooling, the 120 degree (f) air temperature is reduced to about 90 degrees (f) which greatly improves the efficiency of the heat transfer of the condenser coil.
     At lower temperatures across the condenser coil, the air conditioner efficiency improves, the energy use is reduced and the compressor useful life is increased.  The air conditioner produces colder air at a lower energy cost.

Precoolers save energy costs, improve efficiency of the equipment being precooled and extends useful lifetime of the equipment. Other advantages of precoolers depend upon the application.  I.E. in liquid to air heat exhangers such as in the petroleum industry,  several benefits are realized.  Heat transfer rates being increased due to colder air passing over the heat exhanger tubes means other equipment involved in the operation need not be run as long, or hard or, in some instances not at all.

Precoolers are manufactured to fit the application:  Precoolers are sized to fit the appllication.  When ordering precoolers, provide the open face area over which the precooler will be mounted plus an additional 2" on each side and top and bottom to allow for a mounting surface to attach the precooler.
The following table will illustrate the value of a precooler when used with conventional industrial air conditioners:


Table 1:  Carrier Model 50PQ016 Industrial Air Conditioner (without precooler):

A/C performance
Without Precooler
Temperature air entering outdoor coil (degrees f)
Difference 85(f) to 115(f)
Total Capacity (1000Btuh)
-32,400 Btuh
Compressor input (KW)
+2.4 KWh
A/C performance with Precooler
With Precooler TC/KW
-8000 Btuh/ - .5 KWh
Note:  Entering wet bulb is 67(f) CFM = 5500.  Based on Carrier published data.  Precooler performance based on using 4" thick media and results are estimated/interpolated.  Better precooler performance can be achieved by using thicker cooling media.


Precooler construction:  

Housing:  The housing is constructed from Stainless Steel, grade 304.  The sump has fusion (TIG) welded corners and joints.  Sides have in-turned flanges for mounting.  A permanent back-bar is provided across the top with a similar flange for mounting.  A removable top cover is provided for access to media.  A full width media support channel with staggered pattern of punched holes is provided with an air bypass inhibitor plate to prevent untreated air flow under the media.

Cooling Media:  The cooling media is high efficiency rigid media in 4" thick depths.  4" media depth is recommended for industrial applications.  Any depth of media is available on request at time of quotation and design.

Water Distribution:  Water distribution is  controlled by a pump recirculation system with pump, float, make-up water valve assembly and bleed-off system.
     A header pipe with predrilled orifice holes to discharge water upwards to impinge on a stainless steel water deflector and back onto the top of the media across its' full width is standard.  A balancing valve is provided in the riser pipe to the header pipe to meter water flow over the media.

External Plumbing:  External plumbing is to be provided by others.  The sump will contain a drain and overflow fitting welded into the sump (stainless steel coupler, FPT 1/2").  A make-up water fitting is welded into the side of the unit (3/8" stainless steel coupler, FPT).  Fittings can be sized differently if advised at time of quotation and design.

Electrical:  The precooler shall provide a junction box externally mounted to facilitate electrical connections.  All external electrical connections is to be by others.

Drift Eliminator:  Premier Industries offers an optional 2.5" drift eliminator section into our precoolers if there is a concern about water carry over.



Note:  Premier will assist in the design and sizing of precoolers when provided with pertinent data on application.