Does air conditioning remove more heat from humid air?

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Discussion Overview

The discussion revolves around the effects of adding humidity to a room on the performance of an air conditioning (AC) unit. Participants explore whether evaporating water in the room would enhance the cooling effect of the AC or if it would hinder its efficiency due to increased humidity. The scope includes technical reasoning about heat transfer, humidity effects, and the operational mechanics of AC units.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants propose that adding moisture to the air will counteract the cooling effect of the AC, as humid air feels hotter and makes the AC work harder to remove heat.
  • Others argue that evaporating water could improve the cooling effect by removing heat of vaporization, although this may also lead to the AC receiving cooler but more humid air.
  • A few participants clarify that while AC units do remove humidity, the added moisture increases the overall heat load that the AC must manage.
  • One participant suggests that the cooling effect of evaporating water could theoretically balance out the energy required for the AC to condense that moisture back into liquid.
  • There is a contention regarding the roles of AC units versus dehumidifiers, with some asserting that modern AC units also function to remove humidity.
  • Concerns about the efficiency of AC units when faced with increased humidity are raised, with references to the mechanics of heat transfer and condensation.

Areas of Agreement / Disagreement

Participants express differing views on the impact of humidity on AC efficiency, with no consensus reached. Some agree that humidity makes the AC work harder, while others question the mechanics of how humidity affects temperature and cooling.

Contextual Notes

Participants note the complexity of the interactions between temperature, humidity, and AC performance, with some assumptions about the roles of AC and dehumidifiers remaining unresolved.

  • #31
OmCheeto said:
It appears that I made the modern equivalent of the 1861 model.
I folded a paper towel in half over my hand dish washer tool drip dryer, wetted it, and stuck a very light RTD probe between the sheets.

omic.psychrometer.png


As long as the surface tension was able to hold the two halves together such that the RTD didn't fall out, I figured it was working.

ps. After some more observations, I'm having severe reservations regarding the "conventional wisdom" of the primary purpose of the "slinger ring". Although I'm in firm belief that the condensate pool increases the efficiency of a window A/C unit, I think the slinger blade serves more to try and clean up the pool.
I love the hand powered surfactant fluid dispenser and the debris removal tool BUt...' the temperature sensing bulb'...too 20Century
 
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  • #32
256bits said:
Hygrometer, or the preferred name in the 1700's the wiki says by some, the hygroscope.

But then I see you went all high tech with a modification of the wet bulb-dry bulb technique.

High tech, and low brow. o0)
I build a portable version yesterday morning, and took several measurements.
They made no sense.
So I redesigned it.

portable.psychometer.rev.2.png


Code:
location      % RH      mg h2o/kg air      temp (°F)       notes

model 1               
kitchen        61       10.70               74             furthest point from A/C unit. should have the highest moisture content
LR south       58        9.80               72             where I sit and stare at data. should have a median moisture content
MBR south      70       10.10               67             where the A/C unit is located. should have the lowest moisture content

conclusion: there was something wrong with the folded paper towel design
theory: the huge plane of moisture was creating a localized increase in humidity
          
model 2                 
kitchen        63       11.70               75                 
MBR south      60        9.00               69           
Back Porch     44       13.70               91
kitchen        60       11.50               76
MBR south      62        9.30               69
conclusion: "relative humidity" is an annoying concept. look at the "Back Porch" numbers: lowest relative humidity, yet the highest moisture content by mass.

ps. I love doing A/C experiments, as I have a legitimate reason to run my 8000 BTU unit, 24/7.
 

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