How to Ensure the Enough Water Flow in Heat Pump System
Application of differential pressure flow switch in water source heat pump system
(the copy rights belongs to A.YITE TECH --- ZHOU ENSI LTD, if reproduce, must marked the original web address)
Water source heat pump unit is a rapidly developing type of air conditioning, which is widely used in office buildings, shopping malls, residential and other occasions, due to its flexibility in application, and high efficiency and energy saving. For the water source heat pump unit, a large water source heat pump system can be composed of a cooling tower and a low-level heat source. The water source heat pump unit can be divided into two types: water to air type and water to water type.
Because the water source heat pump obtains cooling and heat energy from water, the water flow through each water source heat pump can be consistent with the design flow to ensure the cooling capacity and heating capacity of the unit, and the unit can also Depending on an important condition of operation, if the proper flow can not be guaranteed, the condensing pressure will be too high and the unit will be started and stopped frequently, resulting in failure.
The following is an introduction of the method to ensure the water flow of the water source heat pump.
The V10SS flow switch utilizes a rugged, hermetically sealed reed switch...
Method I: flow balance valve + water flow switch
A flow balance valve is installed at the outlet of the water source heat pump, and the flow meter is used to adjust the flow balance valve to the unit demand flow. The disadvantage of this method is that the flow balance valve is expensive. In addition, the cost of flow balance commissioning accounts for about 30% of the cost of the balance valve, which is also high. In addition, the water flow switch must be installed to provide the water flow feedback signal to the controller of the water source heat pump unit.
If the system does not install a flow balance valve, it will be difficult to ensure the water flow required by the unit. As a result, the refrigeration system is prone to high-pressure protection, and the compressor may fail. In addition, if the water flow switch is not installed, the system operator may not be able to confirm whether there is water flow in the system, which may lead to the compressor starting up and running without water flow, and may also cause compressor failure. In addition, because the flow balance valve adjusts the flow by the way of pressure difference, it will produce certain resistance to the water system.
Method 2. Differential pressure flow switch + ball valve
This method is completed by using the curve of the pressure drop and flow of the inlet and outlet pipes of the casing type or plate type heat exchanger. The differential pressure switch has a clear action and reset flow. Reset flow refers to the water flow required to close the heat exchanger through the water flow of the heat exchanger after the pump runs. Action flow refers to the flow when the flow drops to the opening of the differential pressure switch. Reset flow can detect the flow of the water system If the design requirements are not met, the correct setting of the reset flow of the differential pressure switch can ensure the required water flow through the heat exchanger.
GE-511A Brass body is Pressure Differential Switch with adjustable setpoint. The...
Generally, the reset flow of the differential pressure switch used at the water source side (water side) of the water source heat pump should be greater than 80% of the rated flow, which can basically ensure the proper flow through the heat exchanger. The actual application of the medium pressure differential switch can be installed directly in the unit or on site by the factory. Before installation, the pressure differential and flow test must be carried out to obtain the appropriate pressure differential switch and reset the set value of water flow. The specific use can be achieved by adjusting the opening of the ball valve to close the pressure differential. At this time, 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, it has the characteristics of accurate flow control, no additional resistance to the system, no requirement for the pipe diameter, and no water flow disturbance disturbance. It can replace any kind of target flow switch as the flow control of HVAC water system. This method is a simple debugging, low cost, reliable control of water source heat pump water flow control solution.
Add: Building 17 &22, No.2928, Chuan Zhou Highway, Shanghai, 201319, China