This paper describes an experimental study to determine £, a parameter defined in an earlier analytical study as the fraction of the heat of dilution in packed bed liquid desiccant dehumidifiers that goes into the air stream. ξ was determined at various operating conditions in a packed bed using calcium chloride solution as the liquid desiccant in countercurrent flow with air. ξ has been correlated in terms of L/G ratios, gas Reynolds number, the ambient number, and a new parameter, the desiccant number. An extension of the ε-NTU model incorporating ξ is presented, and comparison with data, both present and those reported in the literature, show good agreement. © 1994, American Chemical Society. All rights reserved.