Where is the metering device located?

Where is the metering device located?

The metering device is located after the condenser coil. There are two kinds of metering devices, thermal expansion valves (TXV) and capillary tubes. Either one does the same thing; they lower the high-pressure liquid pressure by forcing it through a small hole or nozzle.

How does an EEV work?

EEVs. The electronic expansion valve (EEV) operates with a much more sophisticated design. EEVs control the flow of refrigerant entering a direct expansion evaporator. They are controlled by an electronic controller and rotate a fraction of a revolution for each signal sent to them by the electronic controller.

What are the two large classes of metering devices?

The two large classes of metering devices are: Fixed restrictions and thermostatic expansion valves.

What does Txv mean in HVAC?

thermostatic expansion valve
A thermostatic expansion valve (TXV) (see Figure 1) is a refrigeration and air conditioning throttling device that controls the amount of refrigerant liquid injected into a system’s evaporator—based on the evaporator outlet temperature and pressure—called the superheat.

How does a fixed metering device work?

The fixed orifice metering device allows the same amount of refrigerant to enter the coil no matter the demand. As the liquid refrigerant enters the metering device it changes temperature and pressure. A partial amount of the liquid refrigerant flashes into a refrigerant gas or vapor.

What does a piston metering device look like?

A piston is a replaceable metering device with a fixed “bore.” It is essentially a piece of brass with a hole in the center; the smaller the bore, the less refrigerant flows through the piston and vice versa. Some piston systems also allow reverse refrigerant flow, as shown in the diagram above.

What is used to open and close EEV?

EEV Components A small motor called a step or stepper motor is used to open and close the valve port. This allows the valve to precisely control the refrigerant that flows through it. Electronic signals sent to the EEV are usually done by a thermistor connected to discharge airflow in refrigerators.

What are the two types of metering devices?

There are two kinds of metering devices, thermal expansion valves (TXV) and capillary tubes. Either one does the same thing; they lower the high-pressure liquid pressure by forcing it through a small hole or nozzle. The metering device acts like your garden hose nozzle, turning a steady stream of liquid into sprayed droplets.

What does a metering device in a refrigeration system do?

Fluid metering device, regardless of type, is designed to provide two important functions in the mechanical refrigeration system. First, it allows the liquid refrigerant flow into the evaporator in the amount that corresponds to the rate at which the evaporator liquid refrigerant boils into steam.

How does metering devices work?

A metering device provides a pressure drop point. This device has two jobs: 1. It holds refrigerant back in a condensed state; and 2. It feeds refrigerant into the evaporator. When high-pressure liquid enters a metering device, pressure starts to drop as the temperature remains the same until it reaches saturation pressure-temperature.