Results 1 to 9 of 9
Thread: delta T
-
06-07-2010, 04:04 PM #1
delta T
could anybody explain how we find out if theres sufficient air flow by checking delta T ? EG how does 2 temp readings tell you if theres correct airflow across an evap or condenser?
thanks .
-
07-07-2010, 10:33 AM #2
Re: delta T
Does anybody know of any books with the above info in then?
Can you get Garys book over here in England?
-
07-07-2010, 01:08 PM #3
-
07-07-2010, 06:05 PM #4
Re: delta T
When air at certain temp flows through a heat exchanger such as evaporator, the heat in the air is absorbed by the refrigerant in the coil and the air is leaving the coil cooler.
Air flow is designed so that maximum heat is absorbed keeping air throw far enough to cool the entire aria to be cooled.
Therefore, Δt is not a fixed No. but will differ with certain situations.
-
07-07-2010, 06:32 PM #5
Re: delta T
thanks chemi , sachin ,
so delta T changes with different applications , so you couldnt just walk up to say an evap in a cold room , take delta t and work out if theres enough air flow?
-
07-07-2010, 06:50 PM #6
Re: delta T
could anybody explain how we find out if theres sufficient air flow by checking delta T ? EG how does 2 temp readings tell you if theres correct airflow across an evap or condenser?
thanks .
Transpose the formula Q=m x cp x p x dt for m
i.e. m = Q / (cp x p x dt)
m = volume
cp = sh capacity
p = density
Only any good if you know Q and its 100% sensible load
so delta T changes with different applications , so you couldnt just walk up to say an evap in a cold room , take delta t and work out if theres enough air flow? 07-07-2010 06:05 PMQuidvis Recte Factum Quamvis Humile Praeclarum.
Latine dictum, sit altum videtur.
Si hoc comprehendere potes, gratias age magistro Latinae.
-
07-07-2010, 07:14 PM #7
Re: delta T
thanks thrash
whats a good guesstimation ? or correct Delta T , how does these 2 temps tell you that you have correct airflow,
Thanks for your time
-
07-07-2010, 08:23 PM #8
Re: delta T
Consider this situation
A split a/c unit running at full capacity (says 5kw on the nameplate)
You measure air on at 23c and air off at 10c therefore dt =13k
5/(13 x 1.205 x 1.005)
5/ 15.73
vol = 0.318 m3/s
If this looks reasonable for the fan then OK
Get a bit more accuracy by doing the condensor the same way.
Or do it properly using anemometer/ balometer etc..Quidvis Recte Factum Quamvis Humile Praeclarum.
Latine dictum, sit altum videtur.
Si hoc comprehendere potes, gratias age magistro Latinae.
-
07-07-2010, 08:52 PM #9
Re: delta T
Arh thanks trash it's starting to make sense now.
Similar Threads
-
Delta T at lower outdoor temperatures ?
By JOSHUA NAGE in forum Technical DiscussionsReplies: 1Last Post: 10-05-2010, 06:35 PM -
Delta RA Capacities
By Greengrocer in forum Air ConditioningReplies: 1Last Post: 23-10-2009, 05:14 PM -
Star delta
By Deano240 in forum FundamentalsReplies: 8Last Post: 10-10-2009, 12:20 AM -
Centrifugals with VSD VS Centrifugal with star delta starter
By vijay_study in forum FundamentalsReplies: 2Last Post: 25-07-2008, 11:13 AM -
question on delta T values in air conditioning work
By beachfronttech in forum Air ConditioningReplies: 2Last Post: 18-01-2008, 10:06 PM