Kelvin

Run a room's pull-down

Simulate how a room's incoming batch and stock cool against the evaporators chosen for it, and try other figures in the Explore trial.

Pipework, equipment and charge · Updated 7 Oct 2026

  1. 1

    Bring the room onto the pipe layout with Import all rooms, so each of its evaporators knows the room it serves.

  2. 2

    On the room's sheet in Heat Load, fill in Cooling and freezing time: the product item's shape and size, and a surface heat transfer coefficient h with its source.

  3. 3

    On Equipment, link that layout in Linked pipe layout, and enter each of the room's evaporators from its datasheet, with its TD defined as air on less evaporating (DT1) and capacity published as linear with TD.

  4. 4

    Read the room's block under Pull-down: a chart of the room air, the batch and the stock over the run, and the readings beneath it.

A room that can't run yet lists what it still needs, in plain words. Nothing is filled in for it.

What the simulation needs

  • An evaporator imported with a Heat Load room. Evaporators linked to no room on this system are listed as not simulated.
  • A datasheet entry for each evaporator, rated on DT1 and linear with TD. Kelvin doesn't convert a log-mean TD, and without a published TD correction the capacity at any other air temperature is unknown.
  • A published refrigerant factor, if the evaporator is rated for another refrigerant.
  • The product's composition, or its density and conductivities entered with a source; its item size; a surface h with its source; and an incoming batch.

What the readings say

  • The evaporators' capacity at the set point, and how much more they give for each kelvin the air rises.
  • The room air: held at the set point throughout, or how warm it rises and when it's back.
  • The batch's temperature at the heat load's pull-down time and at the end of the run, with how much of its heat is out.
  • The stock held at its warmest, and the highest evaporator duty.
  • Temperatures are mass-average, not the centre of the product.
  • The run is twice the heat load's pull-down time, at least a day and at most a week.

The basis under each room's readings names every method and figure the run stands on, including the product method from ASHRAE Handbook—Refrigeration Ch. 20.

Try other figures with Explore

  • Choose Explore under a room's readings to open a trial beneath them. Change Batch mass, Entering temperature, the surface h, Stock mass, each evaporator's units or Run length, and the trial runs again.
  • Choose Play to run it through, or drag the time slider. The room model shows the air, the batch and stock, the evaporators' duty against capacity and the heat flows at that moment.
  • A trial is never saved. A figure left blank is the room's own, and the link above the knobs resets every figure to the room's.
  • A trial batch of another size carries the room's packaging in proportion. That's Kelvin's reading, and the trial says so.
  • A room that can't run only for want of a usable h or a readable evaporator can still be explored: type a trial h, or a Trial evaporator's Capacity at the set point and TD (DT1). Neither is ever filled in for you.

What isn't modelled

  • Compressor capacity: the evaporating temperature is held, so a rack short of capacity pulls down slower than shown.
  • Defrost off-periods: the coils never stop, and defrost heat is its 24-hour average.
  • The structure's heat capacity, such as panels and slab.
  • Door openings as events: infiltration is the heat load's hourly figure.

Note

The equipment report prints each room's pull-down as the page shows it, from the selection's own linked layout.