This document proposes a horizontal air curtain technology to minimize food waste and energy usage from refrigerator door openings. It observes that when a refrigerator door opens, cool air escapes, allowing warm air to enter and heat up food faster. A prototype was tested that installed nozzles to create a horizontal air curtain when the door opens, reducing air and heat exchange. Testing found the air curtain reduced internal temperature peaks after openings and cut compressor run times, saving energy. With wider adoption, this technology could significantly reduce global food waste and energy consumption from refrigerators.

1. Horizontal Air Curtain:
minimizing food waisting

2. Observed Facts:
• The act of opening the refrigerator door push some fresh
cool air out, noticed by someone feet who’s shoeless
• An ice transportting truck, while loading/unloading: cool air
leaking
• Bar refrigerator with top termometer. It’s value it’s rapidly
increased when the door is opened.
• Reason: density diference due to air temperature diference.
Cool air has higher density then warm or hot air. Being cool
air inside the refrigerator chamber, it leaves it to make room
for warm air, heating food and reducing preservation time.

3. Observed Facts:
Refrigerator wih Short period door Long period door
closed door. openning time: openning time: cool
Whole interior cool air leaving air completely
with cool air. the chamber. wasted.

4. Consequences:
• In a hot summer day, a 15 seconds oppening time pushed
the compressor to work up to 170% addicional time then a
closed door pattern.
• With warm or hot air inside the chamber, food is quickly
heated.
• Eventhought being a short period heating, there’s remarkable
consequences: food reduces it’s preservation time.
• With the increasing number of single living people houses,
the same milk liter will now take longer time to be consumed
in comparison with a house where a whole family lives. -> lot
of unnecessary food waisting !!

5. Testing the energetic losses:
Door opening: internal temperature expectations:
(tests over domestic refrigerator)
• Operation Range, closed door: 2 C  6 C
• Operation time without opening the door: 8 min
• From 6 C to 2 C in 8 min = 0,5 C / minute
• Door opening in a hot day, compressor runs for 22
minutes.
• 22 minutes in 0,5 C/min = compressor beats a 11 C internal
temperature diference, total 13 C internal peak temperature with
single door opening.
• Efects:
• In food, degradation accelerared
• Beverages: continuous temperature change can promote
caracteristics variation.
• In both: unnecessary energy losses

6. Solution proposal:
Horizontal Air Curtain made by exhaust and sucction air nozzles,
instaled in the door knocker.

7. Solution proposal:
Does it work??

8. Prototype:
Obs: prototype project did not predicted installing in-wall tubulation. In
final product conception, it would be only notable a little bit thicker wall.

9. Testing the energetic losses:
Test to evaluate the effects of door opening as a function of
the door opening time.

10. Testing the energetic losses:
Opened door for X seconds:

11. Advantages:
• Reduces hot load infiltration.
• Maximizes the no-perish food storage time.
• Reduces the after door opening compressor running time:
saves energy.
• Weaker compressors and smaller heat exchange area for
the same load: lower production costs.

12. Energy Economy estimation:
• Comercial refrigerator (0 a -6 C)
- Chamber: 497L
- Compressor power: 580 w
One refrigerator in a comercial store (opened 16h/day), door
opened 70 times/day.
• With obtained eficiency, 13%, 2% in electrical energy saved.
• If optimized eficiency of 30%, 4% in electrical energy saved.
• Best scenario: 65% air curtain eficiency, 7,6% in electrical
energy saved.

13. Energy Economy estimation:
• Energy cost (Brasil currency): R$0,45/kWh
• For a air curtain eficiency of 65%
• R$16,45/month economy.
• In 5 years, R$987,20 economy (deflated)
• 36,56 kWh/month economy
• 2193,75 kWh/5 years economy
• Lighting consume in a 100m² comercial office: 320kWh/month
• In a five years air curtain operation, one refrigerator
saves enouth to run the office light for 6,8 months.

14. Internal temperature estimation:
In domestic refrigerator, internal peak temperature after door
opening was about 13 C, without air curtain technology.
• With reached eficiency, 13%, internal peak temperature of
8 C
• If optimized eficiency of 30%, 6,9 C of i.p.temperature.
• Best scenario: 65% air curtain eficiency 4,45 C (assuming a
2 C internal temperature at the moment of the door
opening).

15. Actual state:
• Patent requested
• Talking to refrigerator manufacturer and government.
• Trying to spread the knowledge for the masses, so the people
can ask their manufacturer for the tecnology and antecipate
food and energy saves.
• In wide spread use can save big amounts of energy and food, a big
sustainable gain.

16. Thank you.
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