The power of coolers operating indirectly in unsteady states

Authors: K. Filek, B. Nowak, J. Roszkowski

This article examines and discusses unsteady states of mining surface air coolers operating indirectly.

Coolers working both with and against the flow-direction are evaluated with a special emphasis on their thermal power.

Two components were distinguished in the total power of the cooler : cooling power related to the temperature reduction of the air which is being cooled and its drying power resulting from the condensation of water from the air being cooled.

This work is based on the equations of a mathematical model of air-cooling using the coolers mentioned above, which are presented alongside mathematical derivations from previous articles.

To illustrate the work of the coolers under discussion the results of typical calculations are appended in the form of time-based graphs.

Two situations were taken into consideration: a slow exponential fall in the temperature of the cooling water at the entry to a cooler and a sudden change in this temperature.

The results obtained verify both the time-variable of the power of a cooler in conditions similar to its normal work and the influence of the dynamics of a cooler itself on the change of its power on a time-scale, which can be linked e.g. to the notion of the dynamic identification of a cooler as a component of an automatic control system.