Evaporator Design TD and Humidity Band
The design split between box temperature and suction, and the humidity it holds in the box.
Example
You enter
- Box (room) temperature (°F) 35
- Saturated suction temperature (°F) 25
You get
- Design TD (DTD) 10 F
Details, formula, and sources
DTD = box temp - saturated suction, which sets the box humidity: <=10 F ~90% RH (produce), 12-16 F ~75-80% (meat), >16 F <70% (frozen). A 35 F box on a 25 F SST -> 10 F TD, ~90% RH; a drying 17 F suction -> 18 F TD, <70% RH. A smaller TD needs more coil. The coil rating at the design TD governs.
DTD = box_temp - saturated_suction_temp; humidity band by DTD (<=10 F ~90% RH ... >16 F <70% RH).
The evaporator design temperature difference (DTD) and the resulting box-humidity bands, from refrigeration coil-selection practice, by name.
The DTD-to-humidity relationship is standard published refrigeration coil-selection guidance.
Estimate. AHJ and licensed professional govern.
Field names used by the API: box_temp_f, sst_f, dtd
- Design TD DTD = box temperature - saturated suction temperaturecoil-selection practice
- Humidity bands <=10 F ~90% RH, 10-12 ~80-85%, 12-16 ~75-80%, >16 <70%refrigeration practice
- Coil tradeoff a smaller DTD holds more humidity but needs a larger coilscope of this tile