condenser cpacity

[Noori]

hollo every one
please can sombody show me in which case can I use condenser capacity larger then evaporator in a duct split unit, and why.
best regard and this will be great help.

[Vishwaprasanna]

Hi friends
What i would know that, condenser capacity ever greater than evaporator capacity, if u want still greater capacity it may have another purpose ie; reciever tank as a condenser
I'm i be right

[narkom]

Condenser capacity is evaporator capacity plus compressor power supply. So condenser capacity is always greater than evaporator capacity. You may use an oversized condenser but you must maintain the condensing pressure within range.

[BritCit_Juve]

As narkom says the condenser capacity is generally greater than the evaporator capacity but the use of oversized condensers should be considered carefully.
If the condenser is too large and the unit doesnot contain head pressure control then the unit will over condense and the evaporating temperature will drop, in lower ambients, causing Lp or freezing problems as well as excessive dehumidification.
However an oversized condenser with capacity control is very useful when you have noise issues as the fan would run slower.
All the above is based on the compressor being correctly selected for the evaporator.
Brit

[Noori]

Dear Bricit, Dear narkom.

Thanks for your answer, actually , I want to use an over size condenser for a duct split unit with 25 ton Ref. located in desert as the dirty factor is high and the percent for the fresh air submitted should be twice the conditioned space volume per hour , so, please tell me if my idea is right .

[Para-air]

People need to breathe some O2.If you want a cleaner place inside.You shall filter the air double or several times.And if much fresh air is ventilated,will you sure enough capacity of the split unit?

[nike123]

hollo every one
please can sombody show me in which case can I use condenser capacity larger then evaporator in a duct split unit, and why.
best regard and this will be great help.
If you are referring to standard split system with compressor and condenser in outside unit then answer is NO.
Indoor and outdoor unit has to be of same nominal capacity size. You cannot use outdoor unit of different (higher or smaller) nominal capacity with that kind of split system.
On the other hand, if you have compressor and evaporator indoor and only condenser outdoor you could use over sized condenser with some condensation control equipment (fan speed control).

[narkom]

As I know about desert it is very hot at the day time and cold at the night. So using an over sized condenser with some condensation control equipment is a good idea.

[Noori]

Dear narkom.
The nominal capacity required for the conditioned space with the necessary fresh air and using H2S filter is 52 KW or 16 tons , my question is , which factor I can use to calculate the over size condenser so that the unit will mach the high temperature ( up to 51 0C ) in the day.

[Noori]

Dear nikel.
I have only the indoor unit ( capacity is 52 KW, 16Tons) without compressor ,so , I need to calculate the out door unit with necessary fresh air and using H2S filter, please let me know your idea to calculate the over size condenser with out side temperature up to 51 degrees centigrade.

[Noori]

Dear nikel.
U R absolutely right, the nominal capacity for the indoor unit which I have is 52 KW (16 tons) , and I need to replace the old one with an over size condenser so that the unit will running with good performance and matching the necessary fresh air ( using H2S filters) so please inform me your idea to calculate the condenser capacity with out side temperature up to 51C

[narkom]

For the external air temperature +32C the condenser capacity must be about 74 kW, for the temperature +42C we may use the correction factor 1.162 so the condenser capacity will be 86kW. But what is the correction factor for +51C?? I hope someone knows the answer...

[nike123]

Dear nikel.
U R absolutely right, the nominal capacity for the indoor unit which I have is 52 KW (16 tons) , and I need to replace the old one with an over size condenser so that the unit will running with good performance and matching the necessary fresh air ( using H2S filters) so please inform me your idea to calculate the condenser capacity with out side temperature up to 51C


Your condenser capacity is about 75kW for your conditions (assuming 5°C evaporation and 56°C condensation 5K superheat and no subcooling).
For 5K TD (56 condensation - 51 air in) you will need condenser with 90000-100000 m3/h air flow like this one (http://www.mediafire.com/?wwn5mmwm2my)!

That is condenser of 350kW capacity at 32°C ambient and 47°C condensation temperature!:eek:



But concern here is high condensation temperature of 56°C which may lead to compressor overheat and premature death of compressor. You need to be sure that your compressor is capable for continuous operation with that high condensation temperatures.

Also, what is portion of fresh air we talk about here?

[BritCit_Juve]

As Nike123 says the condensing temperature needs to be very carefully considered. With a 56°C condensing temp the compressor won't be cheap or last long.
It may be possible to use an spray on the intake of the condenser to lower the condensing temp through evaporative cooling when the ambient is too high.
Brit

[Noori]

Dear NIke
Thanks so much for your attention in my project specially the note about the compressor , according to this idea I decide to use condenser and evaporator with two refrigerant circuit.
For the compressor selection I will send u my idea about the type of the compressor that is after I explain these information to the customer.
Best regard.
engineer Noori

[nike123]

Dear NIke
Thanks so much for your attention in my project specially the note about the compressor , according to this idea I decide to use condenser and evaporator with two refrigerant circuit.
For the compressor selection I will send u my idea about the type of the compressor that is after I explain these information to the customer.
Best regard.
engineer Noori



I suggest you, that for that project, you take some consulting from experienced engineer at that field of construction and that conditions. That application is at pretty much extreme end of possible use of air condenser and it require lot of knowledge and experience. Lot of things should be considered when constructing something like that. Compressor overheat is just one of them. Second could be where with excess refrigerant when such a big condenser is not used? Third could be does condenser fan motors will cool sufficiently when outdoor is 51°C. Etc...

[Noori]

Dear Nike123
I will ask carrier or Trane or Mcquay …..etc about the unit selection for such project and I will inform u the results.
Thanks all