PDA

View Full Version : Air cooled condensor sizing







nambiandy
26-01-2008, 02:38 PM
I have a sitiuation , I recevied one Air cooled Condensing unit of 1.5tr capacity at -1degC evaporating and 54 degc condensing . We feel that the condesor supplied is small . As the unit is tripping frequently in HP . we checked all the other parameter which are correct as per practise.
Can some one help us in giving following details

1. What should be the face surface area of condensor ? the condensor supplied has 3.7 sqft of face surface area.

2. How to decide on correct size of condensor

nike123
26-01-2008, 03:02 PM
That is too little data.

What is evaporator cooling capacity at -1°C or what is evaporator mod no.?
What is condenser model no.
What is compressor capacity at that conditions or what compressor model do you have.
What is refrigerant.

nambiandy
27-01-2008, 03:31 PM
Thanks Nike

The compressor model is CR 30 Of kirloskar copeland make (India) Hermatic type , the compressor delivers 16000 btu/hr at -1 degC evaporating and 54 degc condensing.

Refrigerant used - R 22

Evaporator is of matching capacity

regards

Samarjit Sen
27-01-2008, 04:15 PM
What are the physical dimensions, no. of tubes, feeds, fin spacing, rows deep, wether it has subcooling circuit or not, if so the no. of tubes, no. of feeds, tube dia. air flow etc. are required to get the capacity of the condenser. The make of condenser. If possible please provide the above, then may be I could help you.

nike123
27-01-2008, 05:11 PM
Thanks Nike

The compressor model is CR 30 Of kirloskar copeland make (India) Hermatic type , the compressor delivers 16000 btu/hr at -1 degC evaporating and 54 degc condensing.

Refrigerant used - R 22

Evaporator is of matching capacity

regards

This is result from Coolpack software!
Check data to see if they correspond with your case!

http://farm3.static.flickr.com/2182/2222506039_8425519bba_o_d.jpg


http://farm3.static.flickr.com/2075/2223297896_f95d15df23_o_d.jpg


http://farm3.static.flickr.com/2319/2222506237_e3d79932a7_o_d.png

nambiandy
29-01-2008, 02:54 PM
Dear nike.

thanks it is a useful information.


Dear Mr Sen

I do not have those details now.I will Try to get it

Can you suggest some good book on Condesor & evaporator design

Samarjit Sen
29-01-2008, 05:04 PM
If you can get me the details as I had asked for, then I can work out the capacity of your existing condenser. Condenser and Evaporator design is not easy and involves a lot of deep study. The people who can, help are the members of this forum.

If you go through the threads you will find a number of interesting discussions on this.

mohamed khamis
30-01-2008, 03:18 AM
I have a sitiuation , I recevied one Air cooled Condensing unit of 1.5tr capacity at -1degC evaporating and 54 degc condensing . We feel that the condesor supplied is small . As the unit is tripping frequently in HP . we checked all the other parameter which are correct as per practise.
Can some one help us in giving following details

1. What should be the face surface area of condensor ? the condensor supplied has 3.7 sqft of face surface area.

2. How to decide on correct size of condensor

Hi,

It is roughly expected that the face area (length * Height) of the condenser ranges from 0.275 m2 to 0.33 m2. This depends on the air temperture difference and air face velocity. If u can tell me about those parameters May be I could give u the exact sizing. However, to jude on the condenser fits this case or no the Judment should be done on the total surface area not the face "frontal" area.

Cheers

Mohamed

rajgulati
30-01-2008, 01:28 PM
Face velocity should be in-between 4.5 - 5.5 m/sec. Condenser design is depend upon size of tube, thickness of tube. ambient temperature. No. of fins. If you can give me the details i can calculate the area for yyou.

Gary
16-02-2008, 05:08 PM
What are the condenser entering and leaving air temperatures?

What is the liquid line temperature at receiver outlet?

What is the saturated condensing temperature (from pressure/temperature chart)?

powell
19-02-2008, 06:36 AM
It might seem I’m going to over simplify this but, let’s cut to the chase. The Copeland CR30 is a nominal 2.5 HP compressor, R-22 High Temp (0 to 45 F (-18C to +7C). It pumps 16,600 btuh @ +30 F (-1C) SST @ 129F (+54C) CT @ 230-1-50.

Copelands' 2 through 3-1/4 nominal HP, rated 0 to +45 F SST, condensing units use a condenser sized at 32” x 18”, 10FPI, 3 row, and use 2 fans……… roughly 3.75 SF surface area. They rate their units up to an 110F (+43C) ambient.

If your condenser is near this size and specifications and the ambient temperature is not extreme, them you have other problems causing the high head pressure.

Typical causes of high head pressure:

Unbalanced system, load in excess of the design conditions
Air in the system. If so, then check the low side for a leak.
Dirty condenser.
Re-circulating of condenser air. This is a common occurrence when an oversized outdoor weather hood has been installed.
Air flow is restricted thru the condenser.
The ambient temperature surrounding the condenser is too warm. This is common on walk in coolers and freezers when the condensing unit is mounted on the box and closed off by a drop ceiling.
Refrigerant overcharge.
Liquid refrigerant backed up in the receiver.
Restriction in the discharge line due to physical damage or an internal restriction.
Incorrect air flow thru the condenser. Has someone previously installed a new fan motor or blade? Check the rotation, horsepower and blade size, compared to the specifications of the unit.
Fan cycle control out of calibration.
Flooded head pressure control: Receiver too small for summer application.
Flooded head pressure control: Bypass port wedged open due to a foreign material lodged in it, or the port is worn.
Flooded head pressure control: Field adjustable controls are set incorrectly.Regards……………..Powell

allanbaker
19-02-2008, 11:04 AM
I have to agree with Powell. I think that you have a problem with the fundamentals of the system.

But i am impressed with all the system design software the was applied here. I would like to get my hands on that!!

nike123
19-02-2008, 12:12 PM
I have to agree with Powell. I think that you have a problem with the fundamentals of the system.

But i am impressed with all the system design software the was applied here. I would like to get my hands on that!!

It is free!
http://tinyurl.com/2hd4av

allanbaker
20-02-2008, 05:37 PM
Hey Nike that is twice today you have given me work......im gonna start to call you boss

nike123
20-02-2008, 08:23 PM
Hey Nike that is twice today you have given me work......im gonna start to call you boss
Don't!
Finally, after 10 years as project manager, nobody calls me "boss" any more (I am self employed, one-man-company now). ;)

Gary
20-02-2008, 09:29 PM
What are the condenser entering and leaving air temperatures?

What is the liquid line temperature at receiver outlet?

What is the saturated condensing temperature (from pressure/temperature chart)?

To expand on this a little:

The difference between entering and leaving air temperature is the condenser delta-T. Excessive dT indicates insufficient airflow.

The difference between SCT and liquid line temperature is the subcooling. This tells you if liquid is backing up into the condenser (overcharge).

The difference between liquid line temperature and leaving air temperature is the condenser approach. This tells you if there is efficient heat transfer between the refrigerant and the air (condenser coating).

The difference between entering air temperature and SCT is the condenser TD. If all else is within normal parameters and given normal heat load, this tells you about the relative condenser sizing.

powell
20-02-2008, 10:13 PM
nambiandy,

Do you have any follow up details? There's a lot of good input in this thread.

I'm sure the other posting members, myself included, are interested in the results.;)

Powell

sagar45
26-09-2008, 08:35 AM
please send me condenser design book in PDF format on sagar_babar45@indiatimes.com

750 Valve
28-09-2008, 10:00 AM
please send me condenser design book in PDF format on sagar_babar45@indiatimes.com


please send me $100 first... doyourownhardwork@freeloader.com

icecube51
29-09-2008, 07:21 PM
Yo Sagar, you sound like ABBA, give me give me give me.

what do we get ???

Ice

sagar45
15-03-2009, 01:26 PM
i am desinging a condenser for Danfoss MT100 Compressor At Evaporating temperature 7.2 And 55 Condensing temp.Refriegrant R22 . The toatal heat rejection Is het Load + Compressor Work 23.5 KW+ 8 KW = 31.5 KW
the FPI for Condenser iS 10
The Tube Diameter IS 3/8"
pitch Distance Horizontal Is 25.4 mm
Please anyone suggest how can i caqlculate the heat transfer are and Air flow

also how can i select the circuits

nike123
15-03-2009, 03:25 PM
i am desinging a condenser for Danfoss MT100 Compressor At Evaporating temperature 7.2 And 55 Condensing temp.Refriegrant R22 . The toatal heat rejection Is het Load + Compressor Work 23.5 KW+ 8 KW = 31.5 KW
the FPI for Condenser iS 10
The Tube Diameter IS 3/8"
pitch Distance Horizontal Is 25.4 mm
Please anyone suggest how can i caqlculate the heat transfer are and Air flow

also how can i select the circuits


What is maximum ambient temperature, relative humidity and altitude?

sagar45
16-03-2009, 06:05 AM
Ambient temperature is About 43 Degc

Sridhar1312
16-03-2009, 01:11 PM
Air cooled condenser surface area as well as air quantity is important. Normally around 750 to 1000 cfm per TR is required and again depends on the suction and discharge. If the ratio is more Heat rejection factor will be more.

raviperumal
24-12-2009, 05:01 PM
Hi sagar,

Get the HGM100 condensing unit from danfoss, then start your studies!!!!

Ravi

nike123
24-12-2009, 09:28 PM
Ambient temperature is About 43 Degc



What is maximum ambient temperature, relative humidity and altitude?

...............................