What is Air conditioning: Definition and 32 Discussions

Air conditioning (also A/C, air conditioner) is the process of removing heat and controlling the humidity of air in an enclosed space to achieve a more comfortable interior environment by use of powered 'air conditioners' or a variety of other methods including passive cooling and ventilative cooling. Air conditioning is a member of a family of systems and techniques that provide 'heating, ventilation, and air conditioning' (HVAC).
Air conditioners, which typically use vapor-compression refrigeration, range in size from small units used within vehicles or single rooms to massive units that can cool large building. Air source heat pumps, which can be used for heating as well as cooling are becoming increasingly common in cooler climates.
According to the IEA, as of 2018, 1.6 billion air conditioning units were installed which accounted for an estimated 20% of energy usage in buildings globally with the number expected to grow to 5.6 billion by 2050. The United Nations called for the technology to be made more sustainable to mitigate climate change using techniques including passive cooling, evaporative cooling, selective shading, windcatchers and better thermal insulation. Refrigerants used within air conditioners have caused damage to the ozone layer and are also exacerbating climate change.

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  1. S

    HVAC Why is my air conditioner making sounds?

    Hello, I bought an air conditioner 24000 btu Inverter. ( for home). The indoor unit makes strange noises/sounds at night. The pattern is as follows: First, wind blowing and cooling are reduced to 80%. (Similar to fan mode) After some minutes(About 3-4 minutes), Then the sound (sound in the...
  2. Edwina Lee

    B Home mobile air conditioning: Is this a contradiction to thermodynamics?

    I am seeing lots of brands of home portable air conditioners to cool rooms. They are sold through well known nationwide chains such as Currys, Argos in the UK. Customer feedback shows that they really work. But why would they work??? Surely, these portable aircons need to take away heat from...
  3. G

    How can evaporative cooling air conditioning work?

    If evaporative cooling (Such as sweating) is due to the escape of the hottest molecules into the air thereby lowering the total average temperature of the water then that means that that hot water molecule has gone into the air and has made the air hotter, so then how does evaporative cooling...
  4. Annindita94

    I Cooling Time for Air Conditioning

    Please advise for cooling time on air conditioning. I have a project and customer asked me to make a comparison between their requirement and my proposal. And here's the result. Let's say that we provide a room with same capacity as above, function, delta T, load on that room, but ONLY air...
  5. L

    HVAC Efficiency of a homemade Air Conditioning unit

    Hi guys, I used to post on here quite a bit back in 2005-2007 when I was studying Physics in school, I remember it always being a great resource so hopefully I can get some similar help with this "real life" problem I'm having now! We are having a mini-heatwave here in the UK the last few...
  6. Altiano

    Should I close the door when running AC in fan mode

    I have a 3x3.5 (meters) room with a bathroom of approximately 1.5 x 2. I want to know whether to close the door or not, If I running Fan Mode. There is wall in front of my door, about 60 cm, My assumption: Fan mode only circulate the air, If I open the door, I'll bring outside air in, which is...
  7. mechlite

    Possible Air Conditioning System?

    Hello everyone! Summer is coming and instead of buying a $200-$400 air conditioner, I'd figure I could try a DIY version. I came up with a schematic (attached below) and how I think it would work. I feel like I'm missing something blatantly obvious that will make it not feasible. Wondering if...
  8. M

    What do you think about conditioning the outdoor air?

    What do you think about conditioning the outdoor air? Is it impossible? Is it useless? Is there any research about it?
  9. I

    Air conditioning unit with slightly open window

    Hi all, I want to buy an air conditioning unit while they're cheap and I know you're not meant to have any windows open. I have strange windows so cannot use the fishnet attachment, long story short, if I hang the hose out of the window and just try to close the window as much as possible, will...
  10. C

    Does air conditioning remove more heat from humid air?

    Hello, assume I have an air condition unit which is not very strong and thus always runs at full power. If I let water evaporate in the room without adding heat (e.g. by hanging lots of wet towels), will this improve the heat removal by the aircon unit and thus lower the room temperature, or...
  11. M

    Thermofluids Air Conditioning Unit TS diagram

    Homework Statement To plot a TS diagram given the relevant data here http://imgur.com/Q9RNL8P for an air conditioning unit. Homework Equations R134a is being used in an air conditioning unit, steam tables for -5hf 0hf and -5sf 0sf written below in exrapolation. The Attempt at a Solution I've...
  12. Rick Glimmer

    Daytime: Solar->Ice-> Nighttime:Air conditioning

    I am trying to figure out how much ice i need to produce during daytime to cool a bedroom at nighttime. Currently a 9000 BTU Air conditioner with a separate indoor and outdoor unit is more than sufficient. The air conditioning is set to 24 degrees Celsius and the outdoor temperature goes from 32...
  13. M

    Refrigerant for AC and refrigerator

    Can we use same refrigerant for both air conditioner and refrigerator?
  14. L

    Low-energy air conditioning with seawater

    Over a decade back there was a company that sold air cooling devices for cruising sailboats. A sailboat at anchor is chronically short of electrical energy unless one runs a generator, which has its own trade-offs. The essence of operation of these devices was to pump seawater up from some small...
  15. C

    Determine air conditioning cooling time

    how can i calculate the require time for an air-conditioning unit to cool from 30 degree celcius to 22 degree celcius? others parameter can be ignore, i would like to know the formula used and the principal of calculation. thanks
  16. G

    CO2 Gas cooler in Air conditioning

    Homework Statement Investigation on CO2 gas cooler for Automobile air conditioning system Homework Equations I am trying to design a gas cooler for an automobile air conditioning system using CO2. The Attempt at a Solution I have conducted a literature review and understand the super and...
  17. D

    What's cheaper? Ice or Air Conditioning?

    No, not talking about putting a chunk of ice in front of a fan! My father remarked this afternoon, "all that ice you make uses a lot of electricity!" I put ice in my drinks, drink it all down, and my icemaker only makes what it needs. When it's full, it stops. His recommendation was to use...
  18. F

    Most efficient window for an air conditioning unit?

    Hello everyone, I have a practical problem I am looking to solve. In my tiny 300 sq ft apartment in NYC I have 3 windows with exposure to the East, West, and South. It is very hot. I just purchased an 8000 BTU window unit, so in which window will the unit operate with the most efficiency...
  19. S

    Can Prairie Dog Tunnels Inspire Natural Home Air Conditioning?

    I was reading in my physics book about the way prairie dogs design their tunnels so as to produce one entrance with a low pressure in order to create air flow through the system. And it was described as being the result of air velocity over a hill. Has anyone developed something that would...
  20. A

    Thermodynamics question about mass flow rate in an air conditioning unit?

    1. In an air conditioning unit fresh air at 10°C is mixed with warm air at 30°C. If the mass flowrate ratio of warm to fresh air is 1.6, estimate the temperature at which the mixed air leaves the air conditioner. State any assumptions made. and also do you always make the air standard...
  21. J

    Automotive Automotive Air Conditioning System

    I am doing a CADCAM course where I am to design a climate control system for the automobile. I am having difficulty in finding any sources of information in designing a Box (H-Type) Expansion Valve, Condenser Fan (Axial Propeller fan), Blower Fan (Backward Incinded Centrifugal Fan). I am...
  22. F

    Air conditioning unit work more effectively when it is placed high up

    Why does an air conditioning unit work more effectively when it is placed high up a wall?
  23. G

    Can makeshift air conditioning really work?

    The caption of this photo was, "Makeshift air conditioning." I couldn't stop laughing. Someone needs to take a class in thermodynamics.
  24. V

    How to evaluate the performance of air conditioning

    Hello all, We would like to build a system in order to evaluate the performance of air-conditioning. Who can help us to disign this system or introduce the company where we can consult? thank you! Pham Vinh
  25. O

    My air conditioning doesn't cold

    Hello everybody! i have a dodge neon 97 and i want to know how much pressure (PSI) receive the charge suction of the air conditioner compressor system? because i wan't to put the gas refrigerant recharge by myself
  26. T

    Carnot Engines in air conditioning

    Homework Statement Under many conditions, the rate at which heat enters as air conditioned building on a hot summer day is proportional to the difference in the temperature between the inside and outside, Th-Tc. (If the heat enters entirley by conduction,this statement will certainly be...
  27. E

    The human body as a radiator - Air conditioning

    After reading the thread "how many watts does the human body use?" I calculated that my body requires 86 W of energy on average throughout the day. However, I am wondering how much excess energy my body radiates as waste heat (and blackbody radiation) ? Obviously this depends on a lot...
  28. T

    Car Air Conditioning: Energy Usage & Benefits

    I know someone who, on very hot (25+ C) days, runs her car air conditioner until the car becomes comfortably cool, then turns off the AC without turning off the fan or closing the vent. I think this is rediculous. I got to wondering, however, whether it would take more, less, or the same amount...
  29. J

    Optimizing Air Conditioning Efficiency Using Calculus

    i am trying to come up with a project that relates calculus and air conditioning/ heating. I work for an air conditioning company and I am taking a Calculus course in college and we are supposed to do a project that outlines a practical application for calculus. I was thinking perhaps calculus...
  30. J

    Can Calculus be Applied to Air Conditioning?

    i am trying to come up with a project that relates calculus and air conditioning/ heating. I work for an air conditioning company and I am taking a Calculus course in college and we are supposed to do a project that outlines a practical application for calculus. I was thinking perhaps calculus...
  31. S

    Efficient Air Duct Design for 121m^3 Room | Air Conditioning System Calculation

    ----A room has a volume of 121m^3. An air-conditioning system is to replace the air in this room every thirty minutes, using ducts that have a square cross section. Assuming that air can be treated as an incompressible fluid, find the length of a side of the square if the air speed within the...
  32. russ_watters

    Surprising HVAC Lesson: Air Conditioning Costs in Philly vs. Vegas

    One of the guys I work with is taking a course in HVAC and since my boss used to teach it, we got a little lesson today (helping with the homework). The result of the conversation was the realization that it costs significantly more to air condition a building in Philadelphia than it does in...
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