Peltier cooling a 4 cubic foot mini fridge

Question

After doing a fair amount of research I figure I should ask knowledgable people on this topic. I do know that sadly Peltiers are not that efficient.

The problem at hand, I have a off grid solar powered camper setup with a 500 watt foreign pure sine wave inverter that can't start my AC mini fridge (Inrush Current). I am considering retro fitting a Peltier setup to the mini fridge in hopes to solve the problem. From what I read a hard start kit will not help this issue and soft starts are expensive.

The setup:

• A 4 Cubic Foot Mini fridge with the AC Freon system removed.
• 3 TEC1-12706 Peltiers,
• 1 × 40x120mm cooling block run to an 80 mm PC cooling radiator with a 12 volt mini pump and a fan.

Inside the Camper will be kept around 65-70 Fahrenheit. I COULD run the radiator up to the roof and during winter the rad would be exposed to low 40's or under, summer would be different.

Power would be ran through an eBay 20 amp Buck Module with adjustable Voltage and Amps. Also Ran through a 12volt adjustable thermometer. I am not sure yet on the inside/cold side, maybe some heatsinks? I have read that fans add heat inside diminishing the cooling affect. Because the mini fridge is stand up I want to add a removable Styrofoam mid wall to help with the cold air all pouring out each time the door is opened.

I am new to all this stuff and don't really have the cash to get a new 12 volt mini fridge or a new "better" foreign inverter that might still not work. If I am going overkill with the water cooling and could save money with just a hot side heat sink and fans your opinions are much appreciated!

Answer 1

Your project involves an interesting approach to using Peltier modules to cool a modified mini fridge in an off-grid solar-powered camper setup. However, there are several considerations and potential challenges that you should be aware of:

Peltier Efficiency: As you mentioned, Peltier modules are not very efficient. They can generate a significant amount of heat on the hot side, and their overall coefficient of performance (COP) is generally lower compared to traditional compressor-based refrigeration systems. This means you might need more electrical power to achieve the desired cooling effect.

Power Consumption: Peltier modules can be power-hungry. Make sure your solar setup can provide enough power to drive the Peltiers, the pump, and the fan continuously, especially during periods of low sunlight.

Temperature Differential: Peltier modules are most effective when there is a significant temperature differential between the hot and cold sides. If the outside temperature is too high or the heat dissipation is insufficient, the cooling efficiency will decrease.

Water Cooling vs. Air Cooling: Water cooling can be more effective than air cooling, but it adds complexity to your system. Ensure that the water cooling system is well-sealed and won't cause any issues in your camper.

Temperature Control: Maintaining precise temperature control can be challenging with Peltier modules. The adjustable thermometer will be crucial for monitoring and adjusting the cooling process.

Insulation: The removable Styrofoam mid wall is a good idea to help maintain the internal temperature when the door is opened. Proper insulation is crucial for the overall efficiency of your cooling system.

Voltage and Amps Regulation: Ensure that the eBay 20 amp Buck Module provides stable and regulated power to the Peltier modules. Inconsistent power can affect their performance.

Testing and Iteration: Since you're venturing into a DIY project, be prepared for some testing and potential iterations to optimize the performance of your system. Monitor temperature differentials, power consumption, and overall effectiveness.

Safety: Be cautious about electrical safety. Ensure that your setup is well-insulated and that there are no risks of electrical hazards.

Backup Cooling: Consider having a backup cooling solution in case your Peltier setup encounters issues. Depending solely on Peltier modules for cooling critical items like food can be risky.

While your project is ambitious, it's important to manage expectations regarding the efficiency and reliability of Peltier-based cooling. If possible, monitor the performance closely in different weather conditions and be prepared to make adjustments as needed.