Homogeneity index


humidification made simple - Youtube Channel Condair

Humidification Made Simple:

How is the homogeneity index determined?

1. Definition
Determination of the homogeneity index allows simple and clear illustration and comparison of different steam distribution systems and provides comprehensive information about the quality of homogeneous steam distribution.

Homogeneous distribution of humidity is a decisive pre-requisite for the avoidance of stratification in downstream components and for short humidity distances.

Assessment of the homogeneity of steam introduction is not difficult, provided the basic interactions are clearly understood. Steam introduction improves with the increase in the fineness of the steam distribution and the size of the airflow cross section. The number and arrangement of the steam distributors and the type, number and distribution of steam nozzles over this area are of decisive significance.

Pursuant to the requirements of VDI 6022 Sheet 1, steam humidifiers should be operated in such a manner that the formation of condensation in the air hoses is avoided. For this reason, the humidification distance must be adequately sized, and reliable homogeneous distribution of the humidity across the airflow cross section must be maintained.

The homogeneity index is eminently suitable for easy and quick assessment of homogeneous steam distribution in steam distribution systems. 

Airflow cross section: OAir [m2]
Steam distributor: nNH [pcs]
Steam discharge: nSO [single or double sided]
Number of nozzles: nNZ [pcs]
Humidification performance: qS [kg/h]
Homogeneity index: HINX
[non-dimensional value]
calculation of homogeneity index

2. Example

System 1: Esco DR73-A5.10-8 (with 20 nozzles per nozzle assembly and double-sided steam discharge)
Steam output: 100 kg/h
Airflow cross section: 4 m²
Number of nozzles: 100 pcs
Formel, Hinx
System 2: Alternative type (2 nozzle assemblies and 90 nozzles with single-sided steam outlet)
Formel, Homogenitätsindex