Hello Mel,
You asked so ;-
Caravan fridges use a process called absorption, and it uses a sealed continuous loop of pipe which has a controlled amount of a refrigerant fluid inside. The loop of pipe has three distinct areas, an oven, an evaporator and a condenser. The evaporator is inside the fridge at the top and provides the cold surfaces. The condenser is on the back of the fridge and it provides the surface that gets rid of the heat. And the oven is near the bottom under the condenser radiator. The system is sensitive to orientation, and will not work if it's adversely tilted.
The oven can be heated by any external heat source such as gas, 12V or mains which is why its so effective for caravans.
The heat from the oven section causes the fluid to flow around the pipe circuit. Initially it compresses the gas by heating it, and it passes into the condenser coil in the back of the fridge. Here the compressed gas looses its heat and it condenses into its liquid phase as it rises up the condenser coil.at the top of the condenser the pipe narrows as it goes inside the fridge. and as it enters the evaporator coil inside the fridge, the pipe widens and the liquid refrigerant has to expand to fill the space in doing so it reverts to a gas, but it needs external heat energy to do this which it gets by drawing heat from inside the fridge effectively cooling the fridge. The now expanded gas makes its way back to the oven where it is re compressed and starts the cycle again.
Its a carefully balanced thermo dynamic cycle which can be upset by environmental temperature conditions. If the ambient air around the condenser coil at the back of the fridge is too cold then the liquified gas may be cooled too much and it might collect all the systems fluid in the condenser leaving non to expand in the evaporator. The winter covers restrict the amount of cold air reaching the condenser coil ensuring the cycle continues. Equally excessively hot weather will also stop the cycle working by preventing the refrigerant from properly liquefying in the condenser, so some people fit powered fans to improve the heat exchange.
Domestic fridges also have both the Condenser and evaporator coils but the oven is replaced by a much more effective mechanical compressor. These can usually operated over a much wider ambient temperature range, but a word of warning, Many domestic freezers are designed to operate inside houses, and some do not work anywhere as well if used in a garage where the ambient temperature can drop much lower than inside the house. Check the installation instructions for the required ambient temperatures.
Facebook
Twitter