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.

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}