Condensers and COP AC

[mart434u]

Hi Guys,

Need to cool a hot (temp appx = 30 C) humid room (relative humidity = 80%) what type of condenser can offer best refrigeration efficiency ? Thinking maybe evaporative due to the water mist applied to the condenser coil - ?

Also if I increase the indoor temperature what effect would that have on the COP of the refrigeration cycle ? I know COP is refrigerant effect / net energy (i.e. compressor) and increasing the temperature will cause the compressor to work harder but will it not also cause refrigerant effect to increase ? Therefore COP stays same ?

Thanks for you help.

[Magoo]

Have you considered using full fresh air supply and exhaust, will knock the DB temp down and flush humidity out with is as well.

[bob roberts]

>>Need to cool a hot (temp appx = 30 C) humid room (relative humidity = 80%) what type of condenser can offer best refrigeration efficiency ? Thinking maybe evaporative due to the water mist applied to the condenser coil - ?<<


In theory the lower the head pressure and the higher thesuction pressure is the most efficient electrically. The running costs will beas low as you can get.

Now for the practical side, if you are building this systemfor a single household room then the expense of an evaporative condenser mightnot be worth the expense for the amount of power you would save against the basiccost of the system.

As for the condenser it will depend where it is located, evaporativecondensers are quite efficient in dry climates, but not so efficient when youhave high humidity. So if the area is in the tropics then an evaporative systemis not so good.
As for efficiency well there is a limit how low you can gowith the head pressure as the TX valve or capillary tube needs a reasonablehead pressure to operate and if the suction is too high then you cannot removethe moisture from the air, so both have practical limits

Evaporative condensers tend to be all copper which is moreexpensive than the copper coil /aluminium fin type coil that is found in aircooled condensers.
It could well be that buying an off the shelf system couldbe much cheaper over the long period.

If the system is a larger installation then the addedexpense of an evaporative condenser may be worth it if the outside humidity isnot all that high.
There has to be a balance between the installation costs andthe running cost, there is no point in spending a fortune on the install toreduce the running costs by cents, it will never break even.

If you have ideas of spraying a conventional systemcondenser with water, be aware that if the water gets into the condenser fan motorit will burn it out.

I have installed quite a few evaporative condensing systembut they were not in the tropics. They worked well and I like them. They werethe Carrier 9B series from memory, but are no longer made in Australia lasttime I asked. It is a long time ago but I think they made two different condensersand the range they could handle was about 10 to 15 horsepower compressor. Don’tquote me on that.

One thing should be mentioned, if the evaporative condenserhas a pool of warm water in it then there is the risk of legionnaire’s disease.

The other thing is if it is a copper tube aluminium fin coilthen there is the corrosion aspect to consider.