Types of expansion devices in refrigeration

The expansion devices used in refrigeration systems can be divided into fixed opening type or variable opening type. As the name implies, in fixed opening type the flow area remains fixe while in variable opening type the flow area changes with changing mass flow rates. There are basically seven types of refrigerant expansion devices. In throttling devices the pressure of the refrigerant drops down suddenly and due to this its temperature also reduces drastically.

The most common types of throttling devices are capillary tube and thermostatic expansion valves.

REFRIGERATION AND AIR CONDITIONING EXPANSION DEVICES Presented by: Tarun Chauhan. This allows the refrigerant to rapidly cool before entering the evaporator. An expansion device is essentially a restriction offering resistance to. In such cases the throttling valve allows lesser flow of the refrigerant through it. Types of Throttling Devices.

Constant pressure or automatic throttling valve. Thermostatic expansion valve.

As it passes through the expansion valve the evaporating temperature decreases to — deg C and some of the liquid boils off taking its latent heat from the remainder of the liquid and reducing its temperature to below that of the evaporator. These valves are also refer to as metering devices. It maintains a constant pressure in the evaporator. The other type of expansion valve used in HVAC is the fixed orifice. A thermal expansion valve or thermostatic expansion valve (often abbreviated as TEV , TXV , or TX valve ) is a component in refrigeration and air conditioning systems that controls the amount of refrigerant released into the evaporator thereby keeping superheat , that is, the difference between.

Capillary tubes ( cap tubes ) are also used to meter. Manually operated expansion valves These were used for COrefrigeration installations where the compressor was started and stopped by a watchkeeper. The compressor was started with the expansion valve open. Heat Transfer in Evaporators 3. Instead of an orifice, a length of a small diameter tube can offer the same restrictive effect. A small diameter tubing is called ‘capillary tube’, meaning ‘hair-like’.

The inside diameter of the capillary used in refrigeration is generally about 0. Instea they regulate the superheating by adjusting the mass flow of refrigerant into the evaporator, and maintain the pressure difference between the highpressure and low-pressure sides. The evaporation temperature depends on the capacity of the compressor and the characteristics and efficiency of the evaporator. The function of an expansion valve is shown in Figure 4.

Terms in this set (14) What is the function of the evaporator in the refrigeration system. To act as a heat exchanger between air and refrigerant. The expansion valve removes pressure from the liquid refrigerant to allow expansion or change of state from a liquid to a vapor in the evaporator. Refrigerant in the evaporator. The high-pressure liquid refrigerant entering the expansion valve is quite warm.

This may be verified by feeling the liquid line at its connection to the expansion valve. The following expansion devices are designed to pro- vide automatic control of refrigerant flow: 1. Automatic expansion valves. A basic refrigeration cycle consists of four major elements: a compressor, a condenser, a metering device and an evaporator.

As a refrigerant passes through a circuit containing these four elements, air conditioning occurs. The cycle starts when refrigerant enters the compressor in a low-pressure, moderate-temperature, gaseous form.