new defrosting methods

[steveg]

hello has anyone seen any new ways to defrost evaporators other than the conventional hot gas electric etc.

[NoNickName]

On one recent issue of the Internation Journal of refrigeration there was a new way of detecting the starting time for defrosting by using a optocoupler detector across fins. As soon as the signal of the optoreceiver drops below a threshold, defrost is started. They proved this system is 5% more efficient than conventional pressure-temperature-time defrosting cycle.
I know this is not an answer to your question. Just my 0.02 euro.

[Samarjit Sen]

The most popular system is the Electric Defrost, which you must be aware of.

[steveg]

On one recent issue of the Internation Journal of refrigeration there was a new way of detecting the starting time for defrosting by using a optocoupler detector across fins. As soon as the signal of the optoreceiver drops below a threshold, defrost is started. They proved this system is 5% more efficient than conventional pressure-temperature-time defrosting cycle.
I know this is not an answer to your question. Just my 0.02 euro.

thats great thanks for the info, i have been testing different designs of defrost from reverse cycle to microwave devices that will melt the ice. so any other ideas are great

thanks again

[US Iceman]

Water defrost used to be fairly common, sometimes in conjunction with hot gas defrost in ammonia systems.

The photo cell method discussed by NoNickName has been around here in the US for over 20 years, with varying degrees of success I might I add.

Defrosting on demand is a bit like finding the holy grail, it sounds like a good idea but in practice can be extremely difficult to implement due to the many contributing factors.

[chillin out]

LEC domestic freezers have a neat way of timing the defrost, they try to 'optimize' at every defrost.

The pcb wants to run the defrost (for example) the evap probe must get to 10 degC in exactly 20 mins, it then adjusts the interval time to get the desired timing/temp.
It constantly adjusts itself at every defrost to get the optimized energy setting.

Going back to the main point, you could use fresh air if it was on a AC unit with ducts.

Chillin

[Dan]

I think you would achieve smarter answers if you asked more specific questions. Glycol bath defrost is something that can work in certain situations. Shuttered defrosts also can work, although with a certain amount of complexity.

Microwave defrosting is entirely new to me. Can you expand upon this? I love microwave efficiencies, although the coffee loses flavor.

[steveg]

thanks to all who replied to my question. the reason it was a general question is because i want a general idea of what is going on in the vast subject of refrigeration and air conditioning and not just what is used in i.e. air con etc

once again thanks again its a great help


the microwave technology was something i was playing around with to see if it would melt the ice on a coil. it ended up so so big and expensive because of all the safety devices, it was impracticle to use

p.s. in case you have not guessed, im a design engineer...............booo hiss boo

[US Iceman]

There is nothing wrong with being a design engineer. The best overall & final designs are based on input from everyone involved.

I am curious as to some of the test results you may have found. Can you share some of these?

I would be interested in seeing how fast the defrosts were completed with varying degrees of frost accumulation and energy input.