Application of Differential Pressure Flow Switch in Water Source Heat Pump System

Abstract: Since the flow of water flowing through each water source heat pump is consistent with the design flow, the cooling capacity and heating capacity of the unit can be ensured. It is also an important condition for the reliable operation of the unit. If the proper flow rate can not ensure that the condensing pressure is too high, Unit frequent start and stop, resulting in failure, the following to ensure water source heat pump water flow method for an introduction.


Keywords: pressure switch water source heat pump balance valve ball valve

Water source heat pump unit is currently the most rapidly developing type of air conditioning, which is widely used in office buildings, shopping malls, residential and other occasions with the application of flexibility and energy-saving features. For the water source heat pump unit can be combined with the cooling tower and low heat source to form a large water source heat pump system, water source heat pump unit is divided into two types of water - air and water - water source heat pump is obtained from the water cold and heat, so flow After each water source heat pump water flow and design flow consistent in order to ensure the unit cooling capacity and heating capacity, but also a reliable unit work an important condition, if you can not ensure that the appropriate flow rate will likely lead to high condensing pressure and the unit frequently start and stop , Resulting in failure, the following to ensure water source heat pump water flow method for an introduction.

Method one, flow balance valve + flow switch

The flow balance valve is installed at the water outlet of the water source heat pump and the flow balance valve is adjusted to the unit demand flow by the flow meter. The disadvantage of this method is that the flow balance valve is expensive, and the cost of the flow balance adjustment and debugging accounts for about 30% of the balance valve cost. The cost is higher. In addition, water flow switch must also be installed to provide water source heat pump unit controller feedback signal. If the system does not install the flow balance valve will be difficult to ensure the required flow of water units, the results prone to high pressure refrigeration system protection, the compressor may have failed, and if you do not install the water flow switch, the system operator may not be able to confirm the system has no water flow, Compressor may cause the boot run in the absence of water flow, but also easily lead to compressor failure. In addition, because the flow balance valve is based on differential pressure to adjust the flow, will have some resistance to the water system.

Method two, pressure-type flow switch + ball valve

This method is the use of casing or plate heat exchanger inlet and outlet pressure drop and flow curve to complete the differential pressure switch has a clear action and reset the flow, reset flow is the water flow through the heat exchanger after the operation of the pump Make it close the required water flow, the action flow refers to the flow down to the differential pressure switch off the flow, the reset flow can detect the water system flow to meet the design requirements, the correct set pressure switch reset flow can be guaranteed to pass The water flow required for the heat exchanger, which is normally used at the pressure switch reset value of the water source heat pump water side (water side), is greater than 80% of the rated flow so that the flow through the heat exchanger is substantially guaranteed. The actual application of pressure switch can be installed directly in the plant by the factory or installed in the field, before the installation must be tested for pressure and flow to get the appropriate pressure switch and reset the water flow settings, the specific use of By adjusting the opening of the ball valve so that the differential pressure switch can be closed, then the water flow through the heat exchanger has been greater than 80% of the rated flow. At the same time as a flow control switch with flow control accuracy, no additional resistance to the system, but also on the pipe diameter is not required and no interference of water flow disturbance characteristics, can replace any form of target flow switch as HVAC water system flow control . This method is a debugging simple, low cost, reliable control of water source heat pump water flow control solutions.

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