Heat Pump VRF/VRV system

Heat Pump VRF/VRV system:

• It is the advanced version of Cooling VRF.
• It is designed for both cooling and heating purposes, but it will provide either heating or cooling at a time.

For example,  
                      We have installed one heat pump VRF system having 10 indoors. These 10 indoors will provide either heating or cooling at a time. It is not possible to provide partially cooling from 5 indoors and heating from 5 indoors in a single heat pump VRF system.

Parts:

• Inverter Compressor
• Evaporator
• Expansion valve
• Condenser
• NRV(non-reversing valve)
• 4-way reversing valve

Refrigeration cycle of heat pump VRF system:

• This is the main schematic diagram of the heat pump VRV/VRF system.
• In 4 way reversing valve, C is indicated for cooling whereas H is indicated for heating.
• We can change the cycle manually and it also changes its cycle according to the temperature.
• For better understanding here we will discuss the cycles one by one:

            1)Cooling cycle
            2)Heating cycle

Cooling cycle:

Let's start with the compressor. It compresses the low-temperature vapor refrigerant and converts into the high-temperature vapor refrigerant. This vapor refrigerant flows into the 4 way reversing valve. This cycle performs cooling hence the heating line will close. Now vapor refrigerant will pass through the cooling line of 4 way reversing valve as mentioned in the diagram and it will flow into the condenser. The condenser will extract heat from the vapor refrigerant and convert it into the high-temperature liquid refrigerant. This high-temperature liquid refrigerant will pass through NRV(near the condenser) and it will bypass the expansion valve near the condenser, then this refrigerant will flow to the first indoor while going to the evaporator it will pass through an expansion valve and here it will bypass the NRV because it is to the opposite direction of the refrigerant flow. The expansion valve will sense the temperature and according to that, it will pass refrigerant. The remaining refrigerant will go to the next indoor. The evaporator will absorb the heat from the room and convert it into the low-temperature vapor refrigerant. This low-temperature vapor refrigerant will flow into the compressor through the heating line of a 4 way reversing valve and this cycle will continue.

Heating cycle:

Let's start with the compressor. It compresses the low-temperature vapor refrigerant and converts into the high-temperature vapor refrigerant. This vapor refrigerant will flow into the evaporator through a heating line of a 4way reversing valve as per diagram. Here the cooling line of the 4 way reversing valve will be closed. The evaporator will reject the heat into the room, as it has the high-temperature vapor refrigerant as compared to the room temperature. After heat reject, vapor refrigerant will get converted into the high-temperature liquid refrigerant and this will pass through NRV because it has the same direction and it will bypass the expansion valve. After this, it will flow into the condenser where it will pass through an expansion valve and it gets converted into a low-temperature liquid refrigerant. Low-temperature liquid refrigerant will absorb heat by the help of condenser then it passes to the compressor through the heating line of the expansion valve.

Note:

• Evaporator act as a cooling coil in the cooling cycle of the heat pump VRF system.
• Evaporator act as a heating coil in the heating cycle of the heat pump VRF system.

VRV/VRF part 1- Click here

VRV/VRF part 2- Click here