ROOM SENSIBLE HEAT FACTOR (RSHF)

It is defined as the ratio of room sensible heat to the total heat (Fig. 20.29).

where RSH, RLH, RTH = room sensible, latent and total heats respectively.

Figure 20.29 Room and supply air conditions and ADP

Figure 20.30 Grand sensible heat factor

1 Estimation of Supply Air Conditions

When the supply air conditions are not known, then the RSHF line may be drawn from the RSHF calculated value, as described below (Fig. 20.30).

1. Mark point ‘a’ on the sensible heat factor scale drawn on the right hand corner of psychrometric chart. The point ‘a’ represents the calculated value of RSHF.
2. Joint point ‘a’ with the alignment circle or reference point b (t_d − 26°C, ϕ = 50%). The line ab is called the base line.
3. Mark point R on the psychrometric chart to represent the room design conditions.
4. Draw a line RR’ through point R parallel to the base line ab. This line is required RSHF line.