In the household, a frost-free refrigerator is also known as a Non-frost or No-frost refrigerator. The antonym is a Direct cool, Manual or Traditional refrigerator. I use the three terms interchangeably in this article.
Basically, a refrigerator is an assembly of three main components; compressor, condenser, and evaporator. The evaporator tubing in a direct cool refrigerator is run behind the wall of the inner refrigerator surface. That’s why when the refrigerator is operating, it forms ice layer on the inner walls of the freezer compartment.
After hours of operation, it is common for the stuff kept in the freezer compartment to get covered and stuck in ice. And to remove an item from the refrigerator, you may need to first defrost the freezer compartment.
This build-up of frost in the freezer compartment eats up space in the compartment, and the layer of ice impedes the efficient transfer of heat from items that need cooling to the refrigerant in evaporator tube.
The process of defrosting an ice-covered direct cool refrigerator takes time. You would need to switch off the refrigerator and open the freezer door to let warm air flow in to melt the ice. But if you have an urgent need for an item from the refrigerator, you would have to contend with the delay.
This tedious manual defrost process is one of the reasons that lead designers and engineers to come up with no-frost technology.
Frost-free refrigerator makers build it with some extra gadgets that do automatic defrost as it runs. There is no need for you to switch off the refrigerator and open its doors to defrost.
If you open your no-frost refrigerator freezer compartment door, unlike a direct cool refrigerator, all items inside look clean and not covered with ice. Also, there is no thick layer of ice on the freezer compartment walls.
The extra gadgets in the no-frost refrigerator are evaporator fan, defrost heater/element, thermal switch, and timer switch.
How do these components work in harmony to keep the refrigerator frost free?
As the compressor runs, the refrigerant extracts the little heat in the freezer compartment and the fan blows around the remaining cool air. After a no-frost refrigerator has run for long, frost builds up on the evaporator. The thermal switch, which senses cold evaporator surface temperature, closes to connect the heater. The heater melts ice on the evaporator and the resultant condensate drains through a drain pipe. The timer switch puts off the compressor and turns on the heater during defrost.
Those extra gadgets push a no-frost refrigerator’s buying price a little higher, though. Sum total of electricity the gadgets consume is also slightly higher, but negligible.
Self-defrost is a positive step in technology, but it never failed to spark controversy. In the advent of frost free technology, speculation blamed freezer burn on frost-free technology. Freezer burn is the unpleasant phenomenon that occurs in food (especially meat) you keep in a freezer if the meat is exposed to air. The meat dehydrates and oxidizes.
Experts and users have a varying explanation about what causes freezer burn, but they all point to similar effects on meat; the color of meat turns and texture changes, affecting its original taste.
To avoid freezer burn, package your meat in a recommended airtight packaging bag before placing in the freezer. Poor packaging allows air into the bag that facilitates the meat’s dehydration and oxidation.
From the consumer insight, 99.99% of users who’ve had a taste of an ordinary refrigerator and are now on a direct cool, are happier.