Temperature Drop Effect
This is an issue dependent on factors such as HP and LP pressure, temperature and flow rate and the presence of liquids in the LP flow. In general, the theoretical Joule Thomson temperature drop across the SJP does not fully materialise, mainly as a result of the LP flow mixing rapidly with HP gas and the pressure increasing along the mixing tube and diffuser. Low temperature may be experienced if only HP gas passes through the SJP with no LP gas.
In general, the outlet temperature is often lower than the LP or HP temperature by approximately 20% to 30%, whichever has the lower value.