sensible cooling duty of a cooler
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,
Re: sensible cooling duty of a cooler
Quote:
Originally Posted by
samiam
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
Re: sensible cooling duty of a cooler
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.
Re: sensible cooling duty of a cooler
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
Re: sensible cooling duty of a cooler
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
Re: sensible cooling duty of a cooler
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:
Re: sensible cooling duty of a cooler
totally agree with you, 'read the fine print' because you dont always get what you think your getting!!
Re: sensible cooling duty of a cooler
Guys, use the right (and free) software. Coolpack!:)
http://farm3.static.flickr.com/2368/...afbc0f_o_d.jpg
Re: sensible cooling duty of a cooler
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