Throttling device (Expansion Valves)
- 1. Throttling Device Used in HVAC Mohammad Azam Khan {M. Tech}
- 2. Throttling Device A throttling device is the generic name of any device or process that simply dissipates pressure energy by irreversibly converting it into thermal energy. Unlike nozzles and diffusers, throttling devices provide no form of useful energy recovery. They merely convert pressure energy into thermal energy through dissipative viscous flow processes. A throttle need not have same inlet and outlet flow velocities, and, therefore, it may have a significant specific kinetic energy changes across it. Throttles may or may not be insulated, but they are usually such small devices and have such high flow rates that the residence time of the fluid in them is too short for significant heat transport of energy to occur. Consequently, a throttling device is commonly taken to be adiabatic regardless of whether it is actually insulated or not. Mohammad Azam Khan {M. Tech}
- 3. The throttling phenomenon, also known as Joule – Kelvin /Joule –Thompson effect, may be demonstrated by considering a steady-state, steady flow (SSSF) process across a restriction, with a resulting drop in pressure. The restriction can be a porous plug, an orifice plate, a butterfly valve, any type of flow or pressure control valve. Even a geometry like sudden contraction or sudden expansion may give the desired effect Mohammad Azam Khan {M. Tech}
- 4. Orifice Plate Mohammad Azam Khan {M. Tech}
- 5. Porous plug Mohammad Azam Khan {M. Tech}
- 6. Pressure Control Valve Mohammad Azam Khan {M. Tech}
- 7. Thermostatic expansion valve or TEV is one of the most commonly used throttling devices in the refrigerator and air conditioning systems. The thermostatic expansion valve is the automatic valve that maintains proper flow of the refrigerant in the evaporator as per the load inside the evaporator. If the load inside the evaporator is higher it allows the increase in flow of the refrigerant and when the load reduces it allows the reduction in the flow of the refrigerant. This leads to highly efficient working of the compressor and the whole refrigeration and the air conditioning plant. Thermostatic Expansion Valve Mohammad Azam Khan {M. Tech}
- 8. Capillary tube Capillary Tube is a tube with small internal diameter and could be coiled for part of its length. It is installed to the suction line. A filter-drier is sometimes fitted before the tube to remove dirt or moisture from the refrigerant. This device is simple, does not have any moving part and lasts longer. In order to use this device, the amount of refrigerant in the system must be properly calibrated at factory level. Mohammad Azam Khan {M. Tech}