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johnnysoprano
05-08-2005, 05:16 AM
I have absolutely no knowledge of refrigeration and I am currently in process of designing a medication-dispensing unit. This unit maintains a refrigeration system for certain medications and I am currently considering using thermoelectric air coolers for refrigeration system and I was wondering if that is a right choice.

My question is, if the product is going to be used portably for around 2-3hrs once a week or fortnight, in other times it will be plugged in to the mains. It has capacity of 350mm (height) x 440mm (length) 280mm (depth).

Is thermoelectric air-cooling system most suitable for my product and what are the advantages and disadvantages of thermoelectric air coolers over other refrigeration system.

Please give me some answers

Refrigeration Dummy~~

Andy W
05-08-2005, 07:22 AM
Just take a look at the other medical refrigerators on the market, they are either absorbtion or compressor and ***** gas. My understanding of thermoelectric cooling is that it is dependant on ambient temperature, it will only drop a fixed amount of temperature say for example 6oC below ambient temperature, not sure of the exact figure unlike a refrigerator that can maintain say -21oC at an ambient of 40oC. If thermoelectric was the way to go I think that it would of been done by now. There is a cheap way to build a custom made cooling cabinet that would work high or low temperature, us refrigeration engineers have been building custom and one off equipment for special applications for years.

Erik Detroit
06-08-2005, 04:08 PM
Thermoelectrics are inefficient compared to vapor compression or absorption, but for a very small heat load they are often easiest and the extra power is not a concern. Their advantage is that they are very simple and reliable.

In general they are better for small temperature differences, and they get inefficient rapidly as the temperature difference increases.

Try visiting http://www.melcor.com

They have a good shareware performance calculator that will tell you how many thermoelectrics you will need for a given cooling load, and what the COP, current, etc will be.

botrous
06-08-2005, 10:48 PM
Thermoelectric performance is very low comparing it to a compression refrigeration cycle . . . . i would like to learn more about that . . . the latest article i've read about that was in university and i think it came out of my mind since that time , i'll try to refresh my memory