THERMODYNAMIC CYCLES AND CONTROL RULES FOR WATER CIRCULATING SYSTEMS WITH TRANSPIRATION COOLERS

Abstract

The analysis of existing regulatory designing documents on chimney-type and mechanical-draft water cooling towers is carried out. It is shown the documents are out of date and to be improved. The efficiency criteria for water circulating systems (WCS), such as the mass transfer coefficient, efficiency factor of fill packing and cooling curves are lost their applied significance and no condition to solve appropriate problems. To analyse WCS with different coolers, the thermodynamic cycles in the Temperature-Time plot are introduced. The thermodynamic efficiency of WCS, which is equal to temperature difference to cooled water temperature ratio is proved as the integral efficiency index. Diagrammatical thermodynamic cycles for WCS with a cooling tower, sprinkling basin or cooling pond are adduced and comprehensive analysis of their specific operation features is carried out. Three rules for WCS control are formulated: 1) When putting into operation and removal from service of a heat exchanging equipment, it is necessary to observe the equation of a resulting water temperatures drop in both heaters and coolers; 2) The cooler hydraulic load variation without its efficiency decrease, is allowed only within the operation range of its individual performance; 3) The WCS thermodynamic efficiency drop under production and ambient conditions is an evidence necessity to fulfil required maintenance or to repair proper equipment. On the basis of the suggested thermodynamic cycles and their analysis a comparative estimation of cooling towers, the sprinkling basin and cooling ponds is carried out. The transpiration coolers disrepairings which influence the WCS operation efficiency require their timely elimination are indicated.