sensible cooling duty of a cooler

[samiam]

Hi All,
I have received a copy of the cooler manufacturer technical description where he states the following:

Duty (in kW)
Size of the unit
Material of fins / casing
Surface area
Number of fans
Air on / Air off temperatures
Refrigerant in / out (temperatures)
Refrigerant mass flow rate

How do I find the sensible cooling duty of the cooler ?

Regards,

[powell]

Hi All,
How do I find the sensible cooling duty of the cooler ?


I hope I'm reading the question properly. I'm not too keen on the different idioms outside the USA.

Sensible heat of the product to be stored is calculated by the following formulas.

Above freezing
(lbs per 24 hrs) x (temp. reduction F) x (specific heat above frz)

Below freezing
(lbs per 24 hrs) x (temp. reduction F) x (specific heat below frz)


Also, I'll add latent heat of the product.

Latent heat
(lbs per 24 hrs) x (latent heat of fusion)

Regards

[US Iceman]

To my knowledge the stated capacities of all refrigeration coils are based on sensible only cooling. They do not include the effects of latent on the coil performance (even though we know they form frost below freezing or generate condensate above freezing).

The capacities listed are used to meet the specified cooling loads with no regard for latent impacts.

[Billy Ray]

Hi US iceman,

not so sure here in europe!!

Most manufacturers i understand test to eurovent conditions (set out by europe commissionin). These conditions i believe are for 'wet' coils i.e sensible & latent cooling.

Generally i have been told that on stated nominal conditions 80% sensible / 20% latent will be in the order.

I may well be misinformed & hopefully a cooler manufacturer will correct me.

Billy Ray

[Billy Ray]

further more......

its a bit of an open ender..

if you select your compressor based on the cooler at 100% sensible, & if, which is most likely that latent cooling will be performed (due to room conditions)...

The compressor will be undersized..

Billy Ray

[US Iceman]

For air conditioning coils I would agree with you. I think the AC cooling coil capacities are based on a specific sensible heat ratio.

However, for refrigeration coils "they" are listed as sensible only cooling. Then, if you have a coil which operates below freezing the defrost correction factors increase the required coil capacity to account for the time off in defrost.

But please bear in mind I am speaking from my background here in the US.;)

This is one of those subjects where it pays dividends to read the fine print. The literature should say what the cooling capacities are based.

Our methods may be different than yours.:eek:

[Billy Ray]

totally agree with you, 'read the fine print' because you dont always get what you think your getting!!

[nike123]

Guys, use the right (and free) software. Coolpack!:)


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[maltysoft]

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