Open Refrigeration Fixtures in Supermarkets 1

[Drazen]

I would like to hear experiences about taking into account open refrigeration display fixtures in supermarkets.

ASHRAE handbook gives one table which provides net cooling effect of such fixtures.

It is stated assumption, however, that condensers of those fixtures are placed outside cooled room.

In my practice, however, almost all such fixtures have condesing units placed indoor, where they obviously create cooling load, so I am not sure about how to take into account net effect.

 

[MechEngNCPE]

Take the wattage and multiply by 3.414 to get btu's/h. Electrical loads are practically all sensible btw.

 

[willard3]

I think you answered a question that was not asked, MechEngCPE.

 

[MintJulep]

I think he answered exactly the question that was asked.

 

[imok2]

I believe he answered his own question
"where they obviously create cooling load"

 

[Drazen]

thank you for reaction, it seems my question was not clear enough, so i will try to be more focused:

i am mostly concerned about total net influence of those devices,


MechEngNCPE, there are two things that are dubious in you statement (from my point of view), save unit converstion (I live in SI area btw).

First, one is that you seem to appoaach to this device as it is closed refrigerator, so you take only dissipation, while there are clear cooling effects on room created by open refrigerators, to the extent that ASHRAE recommend adding it to winter heating load, to upsize your heating capacity.

Second, should we not concentrate on condenser dissipation, not simple motor dissipation? We know that differnce is mostly related to EER, so heat by condeser could be 4 times of motor rating.

If I am wrong somewhere, I would appreciate corrections, I feel this thread as some brainstorming session.

 

[Drazen]

thank you for reaction, it seems my question was not clear enough, so i will try to be more focused:

i am mostly concerned about total net influence of those devices,


MechEngNCPE, there are two things that are dubious in you statement (from my point of view), save unit conversion (I live in SI area btw).

First, one is that you seem to approach to this device as it is closed refrigerator, so you take only dissipation, while there are clear cooling effects on room created by open refrigerators, to the extent that ASHRAE recommend adding it to winter heating load, to "upsize" your heating capacity.

Second, should we not concentrate on condenser dissipation, not simple motor dissipation? We know that difference is mostly related to EER, so heat by condenser could be 4 times of motor rating.

If I am wrong somewhere, I would appreciate corrections, I feel this thread as some brainstorming session.

 

[Waramanga]

Drazen seems to be talking about stand alone open refrigeration cases. I agree with mecheng in that case (electrical input sensible only) because there isnt even latent cooling, the units usually use compressor super heat to get rid of condensate.

 

[MintJulep]

If the entire unit (case, evaporators, condenser, compressor and fans) are all in the conditioned space then the net cooling load to the space equals the power input.

 

[Ziggypump]

Look up a model number or ask the manufacturer for the heat gain to the space. This number should be calculated already. Of course this is for a self contained unit.

There are remote cooled units, where the condensing unit is located outside the store (usually roof), and there will be little to no heat gain to the space (fan).

Now there are a few things to take into account too. If the cooler is closed, it will act very similar to a refrigerator. If the cooler is open, there will be a little cooling to the space. This is because the fan circulates the cool air around the cooler, and does a fairly good job.

Also, unless you have A LOT of coolers, how much added cooling to the space do you expect?

 

[chicopee]

Look up the nameplates on these units. These nameplates will list voltage, running current and n.o of phases from which you can calculate power inputs in watts and from which you can get values in BTU/HR. The nameplates are usually fastened in the back or under the front edge(near floor level) of these units. Make sure that all these units have hermatic compressors for the above to apply.