Kelvin

Why does my booster's ejector read Not applied?

An entered vapour ejector is applied only at the conditions its entrainment ratio was read at, and only where the balance holds.

Why Kelvin says that · Updated 7 Oct 2026

“Not applied” under Ejector on Cycle means this booster is solved without the ejector, as the same rack with the high-pressure valve alone. The warning at the foot of the section says why, and “Ejector not applied” appears in Events with the same reason.

Why Kelvin does this

Kelvin holds no manufacturer's ejector data and assumes no efficiency. The entrainment ratio is your own selection's, read at five conditions: the gas cooler outlet temperature and pressure, the MT evaporating temperature and superheat, and the receiver pressure. A ratio holds only at the conditions it was read at, so Kelvin applies it only when this cycle runs at them.

The reasons it gives

  • The ratio was read at other conditions. Each condition that differs is named, with the figure it was read at and this cycle's.
  • The entry is incomplete. What's missing is listed under it.
  • It needs parallel compression: with the flash gas bypassed to the MT suction, what the ejector lifts into the receiver goes straight back down.
  • There's no MT load, so no MT evaporator vapour for it to draw.
  • At the ratio entered it would draw more vapour than the MT evaporators make, leave its outlet all vapour, or destroy entropy, which no ejector can do. Check the figure.
  • An ejector is modelled on R-744 only.

What to do

  1. 1

    Under Flash vapor routing, choose HT suction group: the Vapour ejector option needs parallel compression.

  2. 2

    Choose Copy this cycle's conditions to fill Read at with the conditions this cycle runs at. Copying clears the Entrainment ratio, so one read at other conditions is never carried over.

  3. 3

    Select the ejector at those conditions in your own selection tool, and enter the Entrainment ratio it gives, with its Source.

  4. 4

    Check the line under the section now reads “Applied”, then save the design.

If you change the cycle's conditions later, the ejector stops applying until you read the ratio again at the new ones. A design with the ejector switched on can't be saved until its entry is complete; switch it Off to save without it.

Energy works without the ejector, and says so: its ratio is entered at the design conditions only, and each month runs at others.