How does a propane powered cool box cool down? Isn’t the act of burning gas creating heat?!


How does a propane powered cool box cool down? Isn’t the act of burning gas creating heat?!

In: 7

The system uses two coolants, the first of which performs evaporative cooling and is then absorbed into the second coolant; heat is needed to reset the two coolants to their initial states.

The sealed system of a propane-powered fridge holds water, liquid ammonia, and hydrogen gas. A propane flame heats the water and ammonia to its boiling point in what is called the generator. The now-gaseous material then rises into a condensing chamber where it cools and returns to a liquid state. This fluid then flows into another chamber – the evaporator – where it mixes with hydrogen gas. It’s here that a chemical reaction occurs that pulls, or absorbs, heat from inside the refrigerator. Once the solution absorbs enough heat, the ammonia returns to a gaseous state, starting the process over again. This self-contained system doesn’t rely on mechanical, or moving parts, meaning these units remain reliable for years.

A propane powered cool box works by using a chemical reaction to create a cooling effect. The propane gas is burned to produce heat, but the heat is then used to power a compressor that pumps a refrigerant through the box. The refrigerant absorbs the heat from the inside of the box, cooling it down. The heat from the propane is then released outside.

The “propane” part is almost irrelevant. It is just a source of energy. You can achieve the same with a battery and and electric motor. Or a donkey. Or your own muscles.

The essential part is:

Take a closed elastic vessel full of any gas (a soda bottle full of plain air will do). Go to your living room and use force to compress it a bit. It warms up above room temperature. Go to your kitchen and let it cool, while still maintaining pressure on it. Go back to the living room, and release pressure. It cools below room temperature. Let it warm up. Then repeat. In each cycle you are warming a cool bottle in the living room, and cooling a warm bottle in the kitchen. You are transporting heat from the living room to the kitchen. After a while, the kitchen will be warmer, and the living room – colder.

As described, the effect is too small to notice. But if you ever used a manual pump to inflate a car tyre, you must have noticed that it does warm up.

A propane powered cool box cools down by using a thermoelectric process. This process uses the heat generated by burning the propane to power a fan which is used to draw in air from the outside, which is then cooled by a built-in refrigerant. This cooled air is then circulated inside the cool box, cooling down the contents inside.