Calculation of the temperature in ventilated air gap of reinforced concrete cooling tower

Monitoring cooling towers have shown that one of the decisive factors leading to premature failure of the concrete shell is migration of vaporous moisture from the inside to the outer surface, condensation and freezing of the surface layer, which results in the destruction of the shell. The purpose of research is to determine the optimal values of the temperature in ventilated air gap. It is necessary to provide the required thrust and the air throughput to maintain the mode of heat and humidity. Temperature and air velocity affect heat-moisture mode. The calculation was made for the three cases of developing thrust in the gap. First case thrust is created using the heated air by heat exchange with the warm surface of the screen. Second case thrust is created using heated air by dint of a smooth pipe with a diameter of 100 mm, which supply the circulating water. Third case heating is carried out by two ribbed pipes with a diameter of 50 mm with round or square edges, the diameter (side) of 100 mm and increments 100 mm. As a result of research the following conclusions were obtained: air temperature in the gap depends on the outdoor temperature text and it is as higher, as higher the text; medium temperature in height gap t(med) was lower in the case of additional heater than at natural convection; the temperature difference t(0)-t(ext) decreases with increasing text; air temperature at the inlet of the gap t(0) decreases with increasing thickness of the gap; the temperature in the air gap increases from t(0) to t(h). Difference t(h)-t(0) as height, as smaller the thickness of the air gap and outdoor temperature. It is necessary to provide the required thrust in air gap for the effective protection of reinforced concrete cooling tower. Thickness and shape of the gap, the outdoor temperature and the temperature inside the cooling tower depends on it. (C) 2015 The Authors. Published by Elsevier Ltd.