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This article deals with an experimental investigation of thermal performance of mechanical draft wet cooling towers by changing various parameters such as hot water temperature, water flow rate, air mass flow rate and stage numbers of packing. In fact, this research attempts to focus on packing density influences with an emphasis on the role of stage numbers of packing. The results imply that coefficient of efficiency is in direct relation with air mass flow rate, hot water temperature and stage numbers of packing, while it diminishes by increasing the water flow rate. On the other hand, thermal images are provided for visualizing temperature distribution within the studied cooling tower. Afterward, these images are utilized so as to obtain pertinent temperature histograms and also temperature distribution along the vertical and horizontal directions for three packings. Finally, regression analysis is employed in order to derive design equations from the measured data. [ABSTRACT FROM AUTHOR]

This article deals with investigation of probabilistic stability of pipes conveying fluid with stochastic flow velocity in time domain. As a matter of fact, this study has focused on the randomness effects of flow velocity on stability of pipes conveying fluid while most of research efforts have only focused on the influences of deterministic parameters on the system stability. The Euler–Bernoulli beam and plug flow theory are employed to model pipe structure and internal flow, respectively. In addition, flow velocity is considered as a stationary random process with Gaussian distribution. Afterwards, the stochastic averaging method and Routh’s stability criterion are used so as to investigate the stability conditions of system. Consequently, the effects of boundary conditions, viscoelastic damping, mass ratio, and elastic foundation on the stability regions are discussed. Results delineate that the critical mean flow velocity decreases by increasing power spectral density (PSD) of the random velocity. Moreover, by increasing PSD from zero, the type effects of boundary condition and presence of elastic foundation are diminished, while the influences of viscoelastic damping and mass ratio could increase. Finally, to have a more applicable study, regression analysis is utilized to develop design equations and facilitate further analyses for design purposes. [ABSTRACT FROM AUTHOR]

Wet cooling towers play a prominent role in the transfer of waste heat from industrial thermodynamic cycles. However it is a complicated task to dictate and optimize their operational conditions on account of different mass and heat transfer mechanisms between water and air flows. In this research, air mass flow rate, hot water temperature, water flow rate and stage numbers of packing are changed experimentally in order to investigate their influences on the cooling tower performance. As a matter of fact, this research attempts to focus on packing density effects with an emphasis on the role of stage numbers of packing. Consequently, the obtained results indicate that coefficient of efficiency is in direct relation with the hot water temperature, stage numbers of packing and air mass flow rate, while it diminishes by increasing the water flow rate. On the other hand, the captured thermal images and pertinent temperature histograms are investigated so as to visualize and calculate the temperature distribution within the studied cooling tower. Eventually, mathematical equations are derived from regression analysis of the measured data to recommend some practical procedures for the sake of reaching optimum operating conditions of forced draft wet cooling towers. [ABSTRACT FROM AUTHOR]

There are different mass and heat transfer mechanisms between water and air flows inside wet cooling towers (WCTs) so that it is a very difficult task to manage or optimize their operations. In this experimental work, the WCT performance is parametrically investigated in order to understand effects of water flow rate, inlet water temperature, type and arrangement of packing, and mass flow rate of air. Three different types of PVC packings (7, 9 and 18 ribs) are studied in this article separately to investigate influences of rib numbers. Furthermore, operation of the WCT is investigated by changing the inlet water temperature, rib numbers of packing, and flow rate of air and water. Ultimately, a guideline is proposed to reach optimum operating conditions of WCTs by virtue of mathematical equations derived from regression analysis of the measured data. [ABSTRACT FROM AUTHOR]