What will be the advantages and disadvantages of spraying water over an air cooled condenser in an air conditioning system?
Yes, it was proven experimentally that reducing the condenser temperature will increase the refrigeration efficiency. The means of using the evaporative cooling is to be improved for sustainability. Spraying water over an air cooled condenser in an air conditioning system will definitely reduce the age or damage of the condenser materials.
But if the water is hard it may cause scale build up on the surface of the condenser and fins and during dusty weather the situation may become worse when sticky mud forms on these surfaces and may also clog the air passages and thus all these will reduce the heat transfer to the surroundings in result in reducing the efficiency.
You are right, there are many constrains. The climate must be dry and hot, the suitable water must be available. Unlike spraying water over the condenser, evaporative cooler will provide cleaner air over the condenser.
Although I'm not highly experienced in HVAC systems, I investigated sprays and I may motivate the answer from a physical viewpoint.
if you spray water in air, depending on air temperature, water droplets may vaporize much more easily than if it was supplied as a liquid jet since the thermal capacity is lower.
in order to let the droplets vaporize, latent heat of vaporization needs to be taken from air and supplied to water. this can be actually seen as a heat transfer that leads the air temperature to decrease.
this effect might help to increase the HVAC system performance...
hope this helps
Thank you Giuseppe
In fact what we are interested in is to cool the condenser outside surface which is done usually by blowing air over the surface or we may use water to take the heat away. Of course some of the water will evaporate taking its latent heat of evaporation from the metallic surface of the condenser . The rest of the water will be cooled somewhere else and pumped back again. If this water is hard it is very likely that scaling will start to form on condenser surfaces and by time this will hinder the process of heat transfer.
Spraying water on condensers increase the sub-cooing of the refrigerant, which reduces the refrigerant pressure, which in turn reduces the compressor load and thus causes the reduction in compressor kw consumed.
But the matter of concern is how we are spraying the water on the coils, if the coils don't have hydrophilic coating then direct water contact will cause corrosion on the coils and also this will lead to reduced heat transfer between air and coils and the soul purpose of spraying the water will perish.
I feel indirect evaporative cooling makes sense in pre cooling of condenser coil.
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