Innovative Freezer & Air Cooler with Large External Fan Coil Unit for Faster Air Cooling

Welcome to IceFAC

The Window Freezer + air cooler (abbreviated as F-AC) is a fridge-freezer that utilizes part or all of the freezer compartment to cool indoor air during summer. It operates by freezing water at night, when outdoor temperature is lower, and using the stored ice to provide cooling during the day.

What Makes IceFAC Unique?

• Saves electricity by using off-peak energy at night. 
  
• Has a larger external fan coil unit on its top, to more quickly cool indoor air. 
• Cools faster than conventional window air conditioners.
• Portable and versatile for year-round use.

How It Works

• At night, the F-AC freezes water inside a reservoir, taking advantage of lower ambient temperatures to save electricity.
• During the day, the frozen water melts, releasing stored thermal energy to cool indoor air.
• A top-mounted external heat exchanger and air fan (or a fan coil unit) transfer the cool air into the room.
• Like conventional window or portable AC units, the F-AC expels heat outdoors via its condenser.
• Instead of relying solely on water-ice, alternative Phase Change Materials (PCMs) can be used for improved efficiency.
• During summer, the larger external insulated water-ice (PCM) reservoir (the insulated ice box) may be positioned on top of the unit to cool air and save space.

The 3 images above, display an icebox sitting on top of a window refrigerator-freezer (F-AC) with the back of the F-AC exposed to the outdoors.  F-AC has a (optionally removable) larger external fan coil unit mounted on top of it, to more quickly cool indoor air.  A cone shaped heat exchanger (a cone shaped hole for air passage) is inside the icebox. The vertical lines are copper pipes containing water-ice to cool the air passing through the cone inside the icebox.  The blue square is an air fan blowing hot air into the cone shaped hole inside the icebox. The cone shaped hole in the icebox acts as a heat exchanger. At night when temperature is cooler than day, the freezer freezes the ice in the icebox.  During the hot days, the air fan (blue) blows hot air through the hole into the insulated icebox (heat exchanger). Cold air then exits the cone shaped hole and enters the home, cooling indoor space.

Advantages of F-AC Over Conventional Portable or Window ACs

1. True Portable Spot Cooling

• A conventional portable/window AC must stay attached to a window or have access to outdoor air to remove heat.
• The F-AC, however, can be detached from the window during day since it does not require an active evaporator. The ice that was frozen overnight is used for cooling instead.

2. Reduced Size, Cost & Maintenance

• The F-AC eliminates the need for an internal air duct and air fan, reducing both size and manufacturing costs.
• It prevents indoor air pollution caused by dirty, hard-to-clean internal fan coils in traditional ACs.

3. Increased Energy Efficiency

• Energy savings from fan use: According to the U.S. Department of Energy, using a large fan alongside an AC can allow for a 4°F increase in thermostat settings, saving energy costs.
• Better performance in dry climates: The F-AC saves more electricity where day and night temperature differences are large.
• Dehumidification in humid climates: While energy savings are lower in humid regions, dehumidification improves indoor comfort.
• Efficiency increases with temperature: Unlike traditional ACs that become less efficient as outdoor temperatures rise, the F-AC becomes more efficient in hotter weather, as heat transfer to the ice reservoir speeds up ice melting and cooling.

Features	Description
Functionality	Works as a fridge/freezer and an air cooler by utilizing frozen water/ice to cool indoor air.
Portability	Unlike a conventional portable or window AC, F-AC can be detached and moved away from the window while cooling air.
Higher Efficiency at Higher Temps	Becomes more efficient as indoor temperature rises because of faster heat transfer to the ice-PCM reservoir.
Indoor Air Quality	Reduces indoor air pollution by eliminating the need for a built-in air duct and internal fan coil. F-AC has a larger external fan.
Climate Suitability	Suited for dry climate (significant day-night temperature difference) and humid climate by dehumidifying indoor air.
Phase Change Material (PCM)	Uses water/ice or other PCMs with lower/higher melting points to optimize PCM Reservoir volume and cooling efficiency.
Seasonal Adaptability	The top heat exchanger and air fan are detached & removed when AC is not needed (winter, spring, autumn).
Energy Efficiency	Saves electricity by freezing water when outdoor temperature is lower (during night) using stored thermal energy for cooling.

Variations of F-AC

1. Dedicated Evaporator for PCM (water-ice reservoir) Freezing

2. Internal Placement in Freezer or Refrigerator

   • The PCM reservoir can be placed inside the freezer or refrigerator.
   • Different PCMs with varying melting/freezing points can be used.

3. Alternative PCM Usage for smaller water-ice (PCM) reservoir and faster cooling
   

   • There are quite a few PCM materials that freeze around -15 degrees Celsius.  One could consider paraffin waxes or other organic materials with tunable melting points, or eutectic solutions of salts that freeze below 0°C.  The colder the freezing-melting point of PCM material, the smaller the size or volume of PCM reservoir can be for the same amount of cooling and the faster cooling of indoor air.  To make it easier to understand, let’s think in reverse.  Imagine a cabin that in winter needs to be heated by a radiator.  If the temperature of the radiator is 200 degrees Celsius, it can heat the cabin twice as fast as the same radiator at 100 degrees Celsius.

Calculating the Ideal Volume of Water/Ice (PCM) Reservoir

    * One ton (12,000 BTU/hr) AC freezes 2000 lbs of ice in 24 hours.  Ideally, a 12,000 BTU/hr window AC can cool about 500-600 sq ft under normal conditions.

    * A 6,000 BTU/hr AC (½ ton) freezes 1000 lbs of ice in 24 hours.   Ideally, a 6,000 BTU/hr AC can cool about 250-300 sq ft under normal conditions.

Let’s assume a 6,000 BTU/hr AC (½ ton) runs from 2PM to 8PM (6Hours) per day.  That means, the AC does not run for 18 hours per day (24-6=18).

To estimate how many pounds of water a 7 cubic feet chest freezer can freeze in 18 hours, we need to consider the freezer's cooling capacity and efficiency.

Step 1: Freezer's Cooling Capacity
A typical chest freezer has a cooling capacity of about 400 to 1000 BTU/hr, depending on the model.
For this calculation, let's assume the freezer has an average cooling rate of 750 BTU/hr (common for a mid-range unit).

Step 2: Energy Required to Freeze Water
To freeze water at 32°F:
Latent heat of fusion of water = 144 BTU/lb
Energy required to freeze 1 lb of water = 144 BTU

Step 3: Calculate Freezing Energy in 18 Hours
Energy produced by the freezer in 18 hours:
750 BTU/hr×18 hrs=13,500 BTU

Step 4: How Many Pounds of Water Can Be Frozen?

Now, we can calculate how much water can be frozen with the 13,500 BTU of energy:
13,500 BTU / 144 BTU/lb=93.75 lbs of water

Conclusion:
A 7 cubic feet chest freezer with an average cooling rate of 750 BTU/hr can freeze approximately 94 lbs of water  (1.5 cubic feet) in 18 hours, under ideal conditions. 

Assumptions:
Our assumption was that our 6,000 BTU/hr AC (½ ton) runs from 2PM to 8PM (6Hours).  That means, the AC does not run for 18 hours (24-6=18).
Now let’s calculate what size (BTU/hr) AC can freeze 94 lbs of water in 6 hours.

To determine the required BTU/hr AC capacity, we need to calculate the total heat removed during the freezing process. The AC needs to remove 13,600 BTU/hr to freeze 94 lbs of water in 6 hours, requiring a 3,000 BTU/hr AC.
Here's the breakdown:
Latent Heat of Fusion: It takes 144 Btu to freeze 1 pound of water.
Total Heat to Remove: 94 pounds of water * 144 Btu/pound = 13,536 Btu.
BTU/hr Calculation: 13,536 Btu / 6 hours = 2256 BTU/hr.

AC Capacity: Since the AC needs to remove the heat in 6 hours, you need an AC with a capacity of at least 2256 BTU/hr.
Standard AC Sizes: Standard AC sizes are in increments of 1,000 BTU/hr. Therefore, a 3000 BTU/hr AC would be a good choice for this application.

	7 cubic feet freezer	3000BTU/hr Window AC	14 cubic feet freezer	6000BTU/hr Window AC
BTU/Hr	750	3000	1500	6000
Watts/hr	220	879	440	1760
Runs# of Hrs/Day	18	6	18	6
PCM Reservoir Volume CuFt	1.5	1.5	3	3
Cooling area SqFt	125 to 150	125 to 150	250 to 300	250 to 300

Example Refrigerators & Freezers

Model	Capacity	Freezer Size	Cost	Notes
Whirlpool WRT311FZDB	20.5 cu. ft.	6.08 cu. ft.	$808	More than enough space for a 4 cu. ft. ice reservoir.
Frigidaire Chest Freezer	7.0 cu. ft.	Entire unit can be converted	$180	Can be repurposed as a cooling unit in summer.

Alternative Configuration

• A 6.5 cu. ft. PCM reservoir would be equivalent to a 9,750 BTU/hr AC, which can cool approximately 425 sq. ft.
• Instead of purchasing a dedicated 9,750 BTU/hr AC, a portable freezer can be used both for cooling in summer and food storage in winter.

Additional Enhancements

• More powerful water pump for better circulation.
• Low-viscosity antifreeze for improved cooling efficiency.

The F-AC is a highly efficient, space-saving solution for cooling. It leverages thermal energy storage to provide off-grid cooling during peak hours, reducing electricity consumption and improving comfort.

Key Benefits:
✔️ Energy-efficient, saving power by freezing water at night.
✔️ Portable – detaches from the window for flexible cooling.
✔️ Can be used year-round as a fridge/freezer.
✔️ Lower manufacturing and operational costs.
✔️ Environmentally friendly with reduced power consumption.

Comparison: F-AC vs. Conventional Window or Portable AC

Features	Window Freezer + AC (F-AC)	Window or Portable AC
Cooling Mechanism	Uses ice frozen at night for cooling during hot summer days	Uses a compressor and refrigerant system
Energy Efficiency	High – utilizes stored thermal energy	Low – continuously uses electricity while running
Portability	Can be detached & moved away from windows while cooling	Must remain connected to window or outdoor air
Indoor Air Quality	External fan coil.  External fan is larger.	Prone to dust and mold in internal fan coils
Climate Suitability	Ideal for dry or humid climates. Dehumidifies indoor air	Works in all climates but less energy efficient
Seasonal Use	Functions as a fridge/freezer when AC is not needed	Can only be used as an AC
Refrigeration	✔	❌
Installation Required	❌	✔
Ideal Use	Studios, Homes, Offices, RVs, Dorms, Motels, Show Rooms, Factory Floors	Homes, Offices, Rooms

Contact Us

We’d love to hear from you! Whether you have questions, need support, or are interested in licensing, sales, partnership opportunities, feel free to reach out to us.   

Ray Arjomand

📞 Phone: 775-470-3113
📧 Email: Ray@Rabpid.com
📍 Address: 834 Pyramid Way, Sparks NV 89431  USA
🌐 Website: Fridge-Ac.com

2 Utility Patents Granted: U.S. Patent: 10,634,370 & U.S. Patent: 9,080,801

Phone: 775-470-3113         Email: Ray@Rabpid.com            Address: 834 Pyramid Way, Sparks NV 89431  USA           Website: Fridge-Ac.com