Please Help Me

[N Pica]

To whom it may concern:

i am a physics student at Champaign Centennial High school and i have just started my fourth quarter physics project. i chose to study entropy and refrigeration. i am hoping to be able to build a model version of a cooling system. the challenge i am facing is to obtain a pump/compressor and expansion valve, basically any part i need i am searching for. i am interested in figuring out how refrigeration works and i am excited about putting a cooling system together. possibly their are manuals for a project like this or possibly their is a book or website that guide me to a better understanding. i hoped that you might be able to help guide me in the correct direction to find what i am looking for. i am not looking for something huge just something small enough to put together without costing hundreds of dollars. i want it to be simple enough to understand how it works, explain to fellow students how it works, and displayfor my class. thank you for your time and assistance.

Nicholas Pica

[frank]

Hi Nicholas

It's nice to know that there are still some students who are interested in our varied and interesting trade.

Finding books and manuals that explain the fundamentals of refrigeration is quite easy and straight forward - in fact, most people here on the forum will give advice quite willingly.

The problem you are facing is going to be one of personal safety and a lack of specialist, expensive tools. Most refrigeration systems work by compressing refrigerant vapours to high pressures - the new refrigerants operate at up to 20bar! so it is not really something that the untrained individual should be messing with. Then you have legislation. You cannot just obtain refrigerants over the counter, you must have a license in the US and prove that you are within the trade in the UK - much the same thoughout the world since the Kyoto Protocol.

Perhaps you ought to either engage the help of your local college where the refrigeration trainees can build your working model or else just build a non working model for presentation purposes.

Frank

[Prof Sporlan]

If your intent is to study entropy, you'll likely want to consider a Second Law analysis on an operating refrigeration system. An example of how to do this is provided in the ASHRAE Fundamentals Handbook. See chapter 1. These Handbooks are not particularly cheap, so hopefully you can find one in a library. No doubt the University of Illinois library would have it.

Performing a Second Law analysis will allow you to compare the operation of the refrigeration system to that of the reversed Carnot cycle, which is the most efficient refrigeration cycle possible.

Then your problem isn't so much building a refrigeration unit, but finding an operating unit that you can measure temperatures and pressures.

In either case, you will need the help of a refrigeration mechanic.

[herefishy]

Here are some ideas for your experiment...


http://egweb.mines.edu/eggn450/REFRI...D%20DESIGN.htm


vortex tube seems interesting....


http://engr.smu.edu/me/2131/Thermola...ex/vortex.html

maybe you could build one...

http://www.amasci.com/wirbel.txt


buying a vortex tube would cost about $400.00, however...

http://www.grainger.com/Grainger/pro...mId=1611760248


if you want a refrigeration system to "analyze", a water cooler (fountian) may be a good system for your purpose. You may find a local authorized servicer in your area that may have an abandoned machine in their shop that they may give up for your educational purposes.. it is a compact little machine, and water may be a good medium for demonstration purposes, perhaps. This link will let you search your area for a servicer. These machines are "cap tube" systems, however. A qualified person may need to fix accesses or guages to the machine for you.


http://maps.w2gi.com/elkay/


this looks neat.... and really does have some very good information in it... I would print this experiment...


http://mars.uta.edu/mae3183/aircondition.pdf



this is fun!!!! I've got to get back to work, now.... let us know if you need more, N Pica.

[Gary]

Wet your finger and wave it around in the air. You have just experienced a refrigeration effect. Liquid becomes a vapor, and absorbs heat in the process. In this case it is sucking the heat out of your finger.

In a refrigeration system, we force liquid refrigerant to become a vapor, absorbing heat from the refrigerated space. We then reverse the process, forcing the vapor to become a liquid (and reject that heat), so that we can use it again, all in an endless loop.

The portion of the system where the liquid becomes a vapor is called an "evaporator".

The portion of the system where the vapor becomes a liquid is called a "condenser".

The "compressor" pumps the vapor from the evaporator into the condenser.

The "metering device" feeds the liquid from the condenser back to the evaporator, completing the loop.

You might want to start here:

http://www.refrigerationbasics.com

Then come back and we will talk.