Psychrometrics: sensible heat factor for cooling and dehumidification For a process over a cooling coil, with h1 = enthalpy of entering air, h2 = enthalpy of leaving air, and hA = enthalpy at the end of dehumidification (apparatus dew point), choose the correct expression for the sensible heat factor (SHF).

Difficulty: Medium

Correct Answer: SHF = (h1 − hA) / (h1 − h2)

Explanation:

Given data

  • h1: enthalpy of entering air
  • h2: enthalpy of leaving air
  • hA: enthalpy at apparatus dew-point (end of dehumidification line)

Concept/ApproachFor cooling and dehumidification, the sensible heat factor is the ratio of sensible heat to total heat for the 1→2 process and, in terms of psychrometric geometry, is given by the segment ratio along the process line.

Derivation (sketch-based reasoning)Total heat removed = (h1 − h2); sensible component corresponds to (h1 − hA).SHF = (h1 − hA) / (h1 − h2).

Sanity checkIf there is no dehumidification, hA → h2 and SHF → 1, as expected for purely sensible cooling.

Final AnswerSHF = (h1 − hA) / (h1 − h2)

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