Calculating Performance

[Mohammed Qasim]

In order to check whether a high wall split type air conditioner of 24000 BTU/hr is producing its rated capacity in cooling mode I took the following readings from the place :
Indoor Unit
1-Dry bulb temp. of entering air = 80 F.
2-wet bulb temp of entering air = 67 F.
3-Leaving dry bulb temp of air = 60.8 F.
4-Leaving wet bulb temp of air = 57.2 F.
5-Air entering indoor unit cfm = 700 cubic ft/min.

I checked the outdoor dry bulb temp of air = 95 F.

Here I dont know if I have to take a ventilation effect in the calculations or not ,( but if it is exsists, where does it come from ?) so I didnt take it in regard.

When I put these informations on the psychrometric chart the result was far away from the nominal rated mentioned on the nameplate ,where is the mistake please help?

Thanks

[nike123]

That is about 14000 Btu of sensible heat.
You need to give us more details in order to give you any meaningful answer.
Pressures and temperatures of refrigerant in various part of air-con. are needed to tell you what is wrong with your unit.

[Gaafar]

In order to check whether a high wall split type air conditioner of 24000 BTU/hr is producing its rated capacity in cooling mode I took the following readings from the place :
Indoor Unit
1-Dry bulb temp. of entering air = 80 F.
2-wet bulb temp of entering air = 67 F.
3-Leaving dry bulb temp of air = 60.8 F.
4-Leaving wet bulb temp of air = 57.2 F.
5-Air entering indoor unit cfm = 700 cubic ft/min.

I checked the outdoor dry bulb temp of air = 95 F.

Here I dont know if I have to take a ventilation effect in the calculations or not ,( but if it is exsists, where does it come from ?) so I didnt take it in regard.

When I put these informations on the psychrometric chart the result was far away from the nominal rated mentioned on the nameplate ,where is the mistake please help?

Thanks

you have to add latent load to sensible load

[nike123]

you have to add latent load to sensible load

In this particular case there is no latent heat because there is no condensation of water. Put his readings on Mollier chart and you will see that condensation didn't occurred.

[wambat]

Here's what I got from your readongs:
Total Cooling Btu/hr 20,430
Sensible Cooling Btu/hr 14,856
Latent Cooling Btu/hr 5,574
Tons of Cooling 1.7
CFM per Ton Leaving Coil 411.2
Sensible Heat Ratio 0.73
Dry Bulb TD 19.2°
Enthalpy Difference 6.52 Btu/lb
Mass Air Flow Rate 3152.87 lb/hr
CFM Entering Coil 727.7 ft³/min
Apparatus Dew Point 54.2°
Bypass Factor 0.26

[nike123]

I made some mistakes during conversion from imperial to SI units.
Wambat, what software is this?

[Abby Normal]

Entering Air 80/67, v=13.845 ft^3/lb da, h=31.51 Btu/lb da, Dewpoint about 60.3F, grains of mositure 78.6/lb da, 700 CFM

Leaving air, 60.8/57.2, h=24.58 Btu/ lb da, grains of moisture 64.3/lb da, dewpoint about 54.9F

total cooling is about 700/13.845x60x(31.51-24.58)= 21,023 Btu/hr



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