Presented in this paper is an experimental investigation of the steady state air-side pressure drop through a delugable bare tube bundle. The tube bundle forms part of a systematic investigation of the sub-components of a Hybrid dry/wet dephlegmator (HDWD), also known as a secondary steam condenser, used in direct dry cooling for thermal power plants.
A modular bare tube bundle is designed and built to experimentally investigate the pressure drop in a counter flow test facility with 19 mm and 25 mm tubes at various tube depths. For both dry and wet an empirical correlation are developed. For the dry correlation the absolute average error is seen to be 3.2 % between the measured and predicted values and for the wet correlation the absolute average error is seen to be 4.5 %.
The new correlation is used in thermal case study to illustrate the effect the under and over prediction of the air side pressure drop will have on a relatively small evaporative cooler. Two cases corresponding to fan power consumptions of 1.1 kW and 5.5 kW were considered. For the first case the heat transfer rate is predicted lower than the case of Niitsu (1967) and higher than the case of Wallis (1969). For the second case the higher fan power causes flooding and the pressure drop is 22 % higher than what is predicted by Wallis which results in a lower heat transfer rate when compared to the other correlations.