![]() They are electronically controlled through data provided by an electronic temperature sensor, and can open and close multiple times every second to allow very precise control of the amount of refrigerant entering the evaporator. This bulb senses the temperature of the refrigerant leaving the evaporator, and through pressure can open and close to vary the amount of refrigerant entering the evaporator.Įlectronic metering devices, more commonly termed EEV’s or EXV’s (Electronic Expansion Valves), are a more modern and accurate version of a TEV. They use a bulb which is partially filled with refrigerant and is strapped to pipe work exiting the evaporator. Thermostatic metering devices, more commonly termed TEV’s or TXV’s (Thermostatic Expansion Valves), are very common throughout all refrigeration systems. They are most commonly found on small refrigerators like you have in your home. The vast majority of all modern refrigeration & air conditioning systems will use one of these 3 types of metering device.Ĭapillary tubes are simply a length of very narrow tube that causes a restriction to the flow of refrigerant. It is this changing of state within the refrigerant that produces the refrigeration effect, and is the main principle of the refrigeration cycle – more on this a bit later. You may have noticed that in this very brief and simplified introduction to the components, that we have already talked about the refrigerant being a GAS, VAPOUR and a LIQUID. The Evaporator evaporates the liquid refrigerant in to a vapour and then in to a gas before it gets back to the compressor. The restriction is more commonly referred to as a METERING DEVICE as it meters the amount of refrigerant entering the evaporator. The restriction restricts the liquid refrigerant flow and creates a pressure difference between itself and the evaporator. The Condenser cools and condenses the refrigerant gas coming from the compressor in to a vapour and finally in to a liquid. It acts like a pump to create the circulation by compressing the refrigerant gas, creating a pressure difference that drives the refrigerant around the circuit in a continuous cycle. The Compressor can be thought of as the heart of the process. Luckily, their names are quite self explanatory: 1. DC Power Sourcesĭirect current (DC) power sources provide electric current that flows in a constant direction.So let’s have a brief look at each of the components in turn. Every functional electronic circuit needs to have a DC or AC power source. ![]() Power sources supply electrical energy to a circuit in the form of voltage and current. After this article, I recommend reading How to Analyze Circuits, where we discuss more advanced circuit analysis techniques like Kirchhoff’s Current Law and Kirchhoff’s Voltage Law. ![]() You should also be able to get a rough idea of how the circuit works, just by looking at the schematic. It’s not enough to just be able to recognize the components in a schematic. The main goal of this tutorial is to show you the essential schematic components you should know. Each physical component (i.e resistor, capacitor, transistor) has a unique schematic symbol. To start developing your schematic reading abilities, it’s important to memorize the most common schematic symbols. The ability to read electrical schematics is a really useful skill to have.
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