Numerical Modelling and Sensitivity Analysis of Natural Draft Cooling Towers
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A. Dhorat
Abstract
Cooling towers are a relatively inexpensive and consistent method of ejecting heat from several industries such as thermal power plants, refineries, and food processing. In this research, an earlier model from literature was to be validated across three different case studies. Unlike previous models, this model considers the height of the fill as the discretised domain, which produces results that give it in a distribution form along the height of the tower. As there are limitations with the software used (gPROMS) where differential equations with respect to independent variables in the numerator and denominator cannot be solved, a derivative of the saturation vapour pressure with respect to the temperature of the air was presented. Results shown were in agreement with the literature and a parametric sensitivity analysis of the cooling tower design and operating parameters were undertaken. In this work the height of fill, mass flowrates of water and air were studied with respect to sensitivity analysis. Results had shown large variations in the outlet temperatures of the water and air if the mass flows of water and air were significantly reduced. However, upon high values of either variable had shown only small gains in the rejection of heat from the water stream. With respect to the height of the fill, at larger heights of the fill, the outlet water temperature had reduced significantly. From a cost perspective, it was found that a change in the water flowrate had incurred the largest cost penalty with a 1 % increase in flowrate had increased the average operating cost by 1.2 %. In comparison, a change in air flowrate where a 1 % increase in flowrate had yielded an average of 0.4 % increase in operating cost.
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Appendix
Thermophysical properties
The following thermophysical properties used in this work was obtained from Kroger [29]. All temperatures are evaluated in degrees Kelvin.
Specific heat of dry air:
Saturation water vapour pressure:
Specific heat of water vapour:
Specific heat of saturated liquid water:
Saturation humidity ratio:
© 2018 Walter de Gruyter GmbH, Berlin/Boston
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Articles in the same Issue
- research article
- Numerical Modelling and Sensitivity Analysis of Natural Draft Cooling Towers
- Application of Central Composite Design to Optimize Culture Conditions of Chlorella vulgaris in a Batch Photobioreactor: An Efficient Modeling Approach
- A New Control Scheme for Integrating Processes with Inverse Response and Time Delay
- Simultaneous Increase of H2 and Gasoline Production by Optimizing Thermally Coupled Methanol Steam Reforming with Fischer-Tropsch Synthesis
- Fractional PID Controller Applied to a Chemical Plant with Level and pH Control
- Synthesis of Carbon Integration Networks Coupled with Hydrate Suppression and Dehydration Options
- Analysis of the Effects of Neuro-Fuzzy Control Configuration Parameters on PH Neutralization Process
- An Adaptive Fuzzy Feedforward-Feedback Control System Applied to a Saccharification Process
