end of the evaporator on the suction line
None, a TXV operates by it's sensing bulb sensing superheat of the suction line as it exits the evaporator coil.
oppisite side of txv sensing bulb on outlet of evaporator (suction line)
The EPR valve should work reguardless of if the TXV is in the air stream. The TXV in the airflow shouldn't make it act any different since it is sensing the temperature at the bulb instead of at the valve it's self.
The purpose of the External equalizer on the TXV is to compensate for the pressure drop in the evaporator coil , This is done since the superheat calculation is based on the difference in the Saturation temperature corresponding to the Suction pressure (Measured after the coil) and the actual suction line temperature. Now, in a TXV measurement of actual line temperature is accomplished by using the Sensing Bulb and the Measurement of the Suction pressure by the External Equalizer of the TXV. The opening/Closing of the Expansion valve is controlled by the setting of the superheat which is governed by the setting of the Spring.
Difference between txv and exv.
A heat sensing bulb is a specialized light bulb that includes a sensor to detect temperature changes. These bulbs are often used in devices such as heat lamps and incubators to help regulate temperature and prevent overheating. The sensor in the bulb triggers the light to turn on or off based on the surrounding temperature.
a compass
The metering device is sensing and adjusting /throttling in many case, it depends on in what part of the operation /cycle this happens? is it at the beginning? or the end? or the whole time? TXV sensing bulbs can lose their charge, the power head too, the position of the sensing bulb should be at 3 or 9 o'clock not at 12 or 6 due to liquid refrigerant being in the bottom of the suction line at times. During a hot pull down suction line pressures will hunt in times of pulling down a hot room or box . A restriction can do this as well.
Unavoidable in certain situations. Light fixtures are sometimes mounted in the ceiling - the bulb must then be mounted base up or base horizontal.
Usually on one of the sides with it`s sensing bulb going into a well.
Temperature is not a pressure or force acting on a TXV diaphragm. The pressure and forces that typically act on a TXV diaphragm are the evaporator pressure, spring force, and spring adjustment. Temperature indirectly influences the operation of the TXV by affecting the refrigerant pressure.