Scientists discover potential sustainable energy technology for the household refrigerator

Credit: CC0 Public Domain

While many advancements have been in improving its efficiency, the refrigerator still consumes considerable amounts of energy each year.

"Energy efficiency of a normal refrigerator is affected by the heat-insulating property of the thermal barriers of the freezer. This is due to its low inner temperature," explained Jingyu Cao at the University of Science and Technology of China. "There is a in temperature between the freezer of a traditional refrigerator and ambient air temperature and the normal thermal barrier of the freezer causes considerable cold loss."

Cao and his team hypothesized that using part of the cold loss to cool the fresh food compartment could be a promising solution in improving the efficiency of the refrigerator. They describe their findings in the Journal of Renewable and Sustainable Energy.

"The evaporating temperature of the refrigeration cycle depends only on the freezer and appropriate reduction of the evaporator area in the fresh food compartment will not decrease the overall efficiency," explained Cao.

"Most families need one or two refrigerators and they are always on 24 hours a day, 365 days a year. That wastes a lot of . Even if we can save a little energy, that helps the human race be more energy-efficient," said Cao.

Cao and his team are not the first scientists to attempt to improve the efficiency of household refrigeration. Extensive experiments by many different scientists have looked at various parts of the refrigerator to improve , but a definitive solution has not yet been found. In Cao's study, a novel with a loop thermosyphon is put forward to decrease the between the freezer and ambient air.

"One of the surprises was how much energy we saved. The energy-saving ratio of the improved walls got close to 30 percent—more than we had expected. This technology even works in hot climates like the desert."

Although Cao's study is currently based on theoretical calculation, the results are promising. "It has great potential to be popularized as a technology or applied in the renewable energy field, considering its significant energy-saving effect, simple structure and low cost," said Cao.

Explore further

A Refrigerator Converts to a Freezer - and Vice Versa

More information: Jingyu Cao et al, Preliminary evaluation of the energy-saving behavior of a novel household refrigerator, Journal of Renewable and Sustainable Energy (2019). DOI: 10.1063/1.5054868
Citation: Scientists discover potential sustainable energy technology for the household refrigerator (2019, March 28) retrieved 16 September 2019 from
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Mar 28, 2019
We run our house on solar. We had a small 7 cu ft upright refrigerator with 1 cu ft freezer. It consumed about 1300 watts/day. Replaced it with a 15 cu ft chest style freezer; installed a $35 temperature controller that keeps the interior between 37 and 41ºF. It consumes about 400 watts/day. Simple and reliable. If food manufacturers would label the tops of containers, it would be perfect.

Mar 29, 2019
There is no such thing as "cold loss" or "cold gain".
The commodity being dealt with Heat. It is Heat which needs to be controlled.
Cold is nothing more than the absence of Heat.
Cold is not a thing. It is a concept, just like light and dark.
You cannot put in or take away darkness. You put in or take away light.
In the same way, you cannot put in or take away cold. You put in or take away Heat.

Mar 29, 2019
The research described in the story... is actually just a description of how modern refrigerators work.

The first step in doing good science is to understand how the items you are researching actually work. I have a Maytag (Whirlpool) side by side. If you look at the outside walls of the refrigerator they are thicker than the interior wall separating the freezer and the chilled area - they already plan for the heat loss from the chilled area as the thermal energy moves toward the freezer section. The chilling of the warmer food section is NOT done by a separate refrigerant loop, but instead by blowing air from the freezer section into the warmer food section... The refrigerators often have TWO thermostats - one that controls the compressor for the frozen section - and a second mechanical thermostat that opens air vanes such that the air between the frozen and warmer food section can mix.

Improving the efficiency of a refrigerator depends on the loss through the outside walls.

Mar 30, 2019
It consumes about 400 watts/day.

It's impossible to guess what that's trying to say, because the units don't make sense. Should that be average power or energy consumption? In what units?

400 Watts as averaged over a day would be hugely wasteful for a fridge, and 400 kilowatt-hours per day would be completely silly; 400 Watt-days isn't sensible either. A Watt is a measure of rate, and "Watts/day" would be like saying "miles per hour per hour" - as if you were constantly accelerating.

A good chest freezer set with a thermostat to around 40 F can be very energy efficient if you don't keep opening it much - down to about 0.2 kWh/day or 8 Watts average. That's about the power of an LED lightbulb.

Mar 30, 2019
I've never understood why freezers didn't use vacuum insulated panels (VIPs) in the walls and the door. They aren't terribly expensive when compared to the insulating potential over the lifetime. It may just be that 90% of the heat losses are through the door gaskets but I'd think having R25 to R30 insulation would make a bigger difference than all the compressor and fan finessing.

Apr 01, 2019
[q="Eikka"]400 kilowatt-hours per day would be completely silly
jesus fukin khrist, you must be playing dumb..., you guessed the person was referring to w.h/day but pretended like you dont know what kilo is.

0.4 kWh/day ,thats it

Apr 12, 2019
"Cao and his team hypothesized that using part of the cold loss to cool the fresh food compartment could be a promising solution..."

You cannot use "cold loss" to cool Anything.
"Cold loss" is Actually heat gain.
Heat gain does not cool but heats.
This person is studying refrigeration but
has No understanding of it at all.

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