Where is a TEV with an external equalizer typically used?

A thermostatic expansion valve (TEV) with an external equalizer is typically used in evaporators that experience a high pressure drop. This feature allows for more accurate control of the superheat by providing the valve with a better measurement of the pressure downstream of the valve, which can be significantly affected by pressure drops within the evaporator.

In systems with a high pressure drop, the internal pressure at the bulb of the TEV can be different from the actual evaporator pressure that affects the refrigeration cycle. The external equalizer line connects to a point in the evaporator, providing feedback on the actual pressure, thus enabling the TEV to adjust more effectively to changes in load and ensuring optimal performance and efficiency.

This setup helps in preventing issues such as excessive superheat, which could lead to insufficient cooling or compressor damage, making it particularly important in systems where the pressure drop is significant. In contrast, applications with low pressure drops or those that do not experience variable temperature profiles may not require the external equalizer, as they can function adequately with the standard internal sensing.