Refigeration and Air Conditioning

Nothing really except their applicaiton. The air conditioner blows air over the evaporator and that air is sent throughout the conditioned space where an refrigerator/freezer (at least in small ones) simply set the evaporator into the space and to be conditioned and rely on natural convection to move air across the coils.

Of course their are different types of "air conditioners" that don't use a refrigeration cycle such as "swamp coolers" that operate differently but I assume your talking about mechanical systems.

thank you sir for your valuable information

Air conditioner and refrigeration uses the same principles, but are designed for different output temperatures. Both use fans to move air throught the evap coils. Try opening your frig when the motor is running. As stated, small friges use convection (i.e. dorm friges places the evap coils in the same insulated compartment). The main difference is the output temperatures which are basically a function of the type of gas used, expansion valve orifice, and evap tube size.

As Big6ft6 has said, they are essentially the same machines. Common home-use dehumidifiers are also the same basic machine. The location of the condensor (the "hot" coil) is a key difference among the various versions. In an airconditioner, the hot coil and its cooling fan must be outside the conditioned space, (and in most systems, the compressor is in that same location). On a refrigerator, it would make sense to put the hot coil outside too (at least in warm weather) but the total amount of heat pumped out of the small and very well-insulated volume of the refrigerator is usually so slight as to be barely noticeable in the living space.

A demudifier puts both coils in the living space, with a common fan that blows over both. The cold evaporator then causes moisture to be condensed out of the air, and the warm condensor coil reheats the dried air. The air ends up a little warmer in the room where the dehumidifier is running, because the system is not 100% efficient.

The air is warmer exiting a de-humidifier MAINLY from the rejected heat when water is condensed (latent heat) from the air and NOT from the system being less than 100% efficient! (although that does add heat)

Google the latent heat of vaporization of water - when it condenses it is the opposite, liberating the latent heat, and if my memory serves me correctly is about 540 Calories per gram of water to change state between a gas and a liquid, with no change in temperature.

While air conditioners, heat pumps, de-humidifiers and refrigerators possess analagous parts and are basically similar in operation there are substantial differences in the design and sizing of evaporators, condensers and choice of compressors, throttling valves or orifices, refrigerant pressures in various parts of the system etc., and even the choice of refrigerant to optimize the boiling point v.s. pressure characteristics for the specific application since they all operate in different temperature ranges. In other words, it is not just the different arrangements and/or locations of the same parts or difference in BTU capacity.

Good point, re latent heat. I hadn't really thought a lot about it, and had assumed that the heat rise was due mainly to system inefficiencies -- but without even doing the calculations, I am sure you are right. Thanks.

To clarify what the other posters have stated: Air Conditioners and refrigerators operate on exactly the same principle - a vapor-compression refrigeration cycle. However application and thus the design details of the the two systems are considerably different. One notable difference is duty cycle. Air conditioners are relatively light duty cycle devices compared to refrigerators. GE learned this in the late 1980's when they tried to adapt a rotary air conditioning compressor for use in household refrigerators. The in-warranty failure rate was near 100%.

One last note is that some air conditioners and refrigerators use the absorption cycle which while still considered a "mechanical" vapor-compression cycle, has the compressor replaced by a generator, absorber and liquid pump. Instead of a conventional refrigerant, it uses ammonia and water along with a heat source.

Such a residential refrigerator or air conditioner would typically use natural or LP gas, while a large commercial unit might use steam to provide the heat energy to drive the cycle. So a comparison involving an absorption cycle refrigerator with a compressor driven air conditioner or vice versa would be more complicated.

Interestingly enough, (The) Albert Einstein was granted a patent for an improved verson of this technology before he achieved fame.

The 'Einstein Cycle' used butane, ammonia and water in it. A copy of the US version of the patent can be found at google.com/patents ... there were UK and the initial patent was German and both of those are a 'little different' than the one filed in the USA. If you are looking it up, the title on the patent is 'Refrigerant' or 'Refrigeration', but it was granted to Albert around 1945 or so if I remember right.

THE DIFFERENCE IS THAT FIRST IN REFRIGERATION REALLY YOU DO NOT APPLY FLUID MECHANICS CONCEPTS AS THE AIR CIRCULATING THROUG DUCTS AND SO ON

ALSO IN SOME CASES YOU HAVE TO CONTROL THE TEMPERATURE AS WELL AS THE HUMITY

BUT INTO THE REFRIGERATION YOU DO NOT APPLY THOSE CONCEPTS

ANY QUESTION RELATIED ON THAT LET ME KNOW

REGARDS

ERIC

Silly me!

And all this time I thought fluid mechanics was involved internally and externally in all these devices. And get this: I even thought air was a compressible fluid ... boy am I stupid!!!!!

I guess I should have googled "Fluid Dynamics" before I made such a fool of myself.

Thank you so much Eric.

If you don't have to control the humidity in a refrigerator's freezer then what is the difference between a frost free fridge and and one without that feature?

GORDIE!

Most 'frost free' use a short heating cycle, then cool it down again. Sometimes extra but small electric heaters, sometimes reversing the cycle of the coolant (yes, reversing valves are involved and a bit of control circuitry, but nothing to dramatic).

Wait a minute. The question was "what is the basic difference" . No need to get long winded about this there is only one . The operating discharge temp! IE. 55 vs 38.

Del

I think you can assume the original poster was looking for something less obvious: after all, I'd be almost certain he has opened a refrigerator door. If your fridge discharge temp is 38 degrees, you must have a lot of rotting frozen food.

The basic difference between an air conditioner and a refrigerator is that a refrigerator incorporates an insulated box around the cooling coils. An air conditioner discharges the cooled "conditioned" air into a space of the users choosing.

He didn't say freezer!

Del

But is a very rare fridge in which the evaporator coils are located anywhere other than in the freezer compartment, and connected remotely to the refrigerator compartment by ducting. That little knob that sets the refrigerator section temp is not a thermostat -- it's a simple vent control. So when you leave the door closed for a long time, it is not unusual for your milk (etc) to freeze. The evap coils are typically around 0 degrees f.

I have even seen some nice fridges that do have a thermostat for the fridge compartment that opens a damper and turns on a fan to circulate cold air from the freezer.

Gordie.

In the broadest sense air conditioning can refer to any form of cooling, heating, ventilation or disinfection that modifies the condition of air.

A refrigerator is a cooling appliance for the storage and preservation of perishable food.

Thats basic!