In this article, we will discuss a VRF heating and cooling system. This system allows buildings to provide heating and cooling from the same system..
In this article, we will discuss a VRF heating and cooling system. This system allows buildings to provide heating and cooling from the same system.
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We usually want a system that can cool in the summer and heat in the winter. For this we need a reversing valve, this has a sliding connector inside. There are many ways to accomplish this, but in this example we will use two regulators and two check valves. The hot gases discharged from the compressor are sent to the reversing valve in heating mode. The valve slides to send hot refrigerant directly to the indoor heat exchanger to provide heating. It then flows through a check valve but the second valve blocks the flow so it has to flow through the expansion valve and from there it can flow to the outdoor unit where it collects more heat energy and then back to the compressor.
In cooling mode, the valve slides and the hot gas is sent directly to the outdoor unit where the heat energy is evacuated. It then flows through one check valve and the other expansion valve before entering the indoor unit where it absorbs heat from the room and thus provides cooling.
The refrigerant then returns to the compressor. Well, coolant has an extremely low boiling point. Take r410a for example, it boils at -48.5 degrees Celsius while water boils at about 100 degrees Celsius. These numbers change with pressure, but as long as the air is above boiling point temperature, a refrigerant will boil and we can absorb heat energy from the air. You can see that this container is filled with a liquid and just by using the heat of my hand I can boil it and evaporate it. It will then condense into a liquid as it cools, so even in winter we can capture heat energy from outside air.
The compressor will pack this into a very small volume which will raise the temperature and pressure to a usable level and this heat energy will be released into the room. Obviously, the colder the air, the more difficult it is to capture this heat..
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