EXERGY ANALYSIS OFTHE CROSS CURRENT COOLING TOWER

Abstract

The cold water needs to be circulated through the steam condenser of a thermal power plant in order to carry out the waste latent heat of condensation from steam. The hot water leaving condenser needs to be cooled in order to re-circulate it through condenser. Hence the hot water is passed through a cooling tower to reject waste heat to the ambient air through convection and mass transfer. The augmented cost of energy and scarceness of water has made researchers to focus on performance investigation of cooling tower as energy conservation opportunity. The thermal efficiency is generally used to measure performance of cooling tower which is evaluated from properties of the fluids. However this method is inefficient to investigate the major causes of irreversibility inside the cooling tower. Therefore, an exergy investigation is initiated to synchronize with the energy investigation of a cooling tower. This research paper includes the investigation of the thermal performance of a cross current cooling tower through energy balance, mass balance and exergy correlations. The variation of fluid properties with flow direction of fluids and exergy loss within the cooling tower are examined and authenticated through test results. The outcomes of study have shown that the analytical exergy loss is lower than the experimental exergy loss and the exergy loss varies with length and height of the cross current cooling tower. Further the influence of variation in size of cooling tower on exergy loss is evaluated analytically and found that the increase in length of cooling tower than the height reduces exergy loss by 8.18% improving thermal efficiency of cooling tower by 3.57%.

Keywords

• Evaporative Cooling
• Cross Current
• Cooling Tower
• Exergy

References

1. [1] Ren C, Li Nianping, Tang G. Principles of exergy analysis in HVAC and evaluation of evaporative cooling schemes. Build Environ 2002;37:1045-1055. https://doi.org/10.1016/S0360-1323(01)00104-4.
2. [2] Thirapong M, Wanchai A, Somchai W. An exergy analysis on the performance of a counter flow wet cooling tower. Appl Therm Eng 2007;27:910-917. https://doi.org/10.1016/j.applthermaleng.2006.08.012.
3. [3] Bilal AQ, Syed MZ. Second-law-based performance evaluation of cooling towers and evaporative heat exchangers. Int J Therm Sci 2007;46:188-198. https://doi.org/10.1016/j.ijthermalsci.2006.04.014.
4. [4] Thirapong M, Wanchai A, Somchai W. Effects of inlet relative humidity and inlet temperature on the performance of counter flow wet cooling tower based on exergy analysis. Energy Convers Manag 2008;49:2795-2800. https://doi.org/10.1016/j.enconman.2008.03.019.
5. [5] Mani S, Rajagopal S, Sankaranarayanan R. Energy and exergy analysis of counter flow wet cooling towers. Therm Sci 2008;12:69-78. https://doi.org/10.2298/TSCI0802069S.
6. [6] Ebrahim H, Reza S, Mozaffar AM. Thermal performance of cross current cooling towers in variable wet bulb temperature. Energy Convers Manag 2010;51:1298-1303. https://doi.org/10.1016/j.enconman.2010.01.005.
7. [7] Wua JM, Huang X, Zhang H. Theoretical analysis on heat and mass transfer in a direct evaporative cooler. Appl Therm Eng 2009;29:980-984. https://doi.org/10.1016/j.applthermaleng.2008.05.016.
8. [8] Santos JC, Medeiros JM, dos Santos JC, Gurgel JM, Marcondes F. Analytical solution for the simultaneous heat and mass transfer problem in air washers. Int J Refrig 2011;34:353-361. https://doi.org/10.1016/j.ijrefrig.2010.06.016.

9. [9] Wang L, Nianping L. Exergy transfer and parametric study of counter flow wet cooling towers. Appl Therm Eng 2011;31:954-960. https://doi.org/10.1016/j.applthermaleng.2010.11.019.
10. [10] Kannan A, Varun H, Bhuvanesh K, Philip L, Bhallamudi SM, Reddy KS. Simulation of a cross flow wind aided evaporator. Desalination 2014;340:18-29. https://doi.org/10.1016/j.desal.2014.02.016.
11. [11] Santos JC, Barros GDT, Gurgel JM, Marcondes F. Energy and exergy analysis applied to the evaporative cooling process in air washers. Int J Refrig 2013;260:1-8. https://doi.org/10.1016/j.ijrefrig.2012.12.012.
12. [12] Dileep K, Tayaba Z, Awais J, Sajid AB, Muhammad B. 4E (Energy, Exergy, Economic and Environmental) Analysis of the Novel Design of Wet Cooling Tower. Journal of Thermal Engineering 2020;6(3):253-267. https://doi.org/10.18186/thermal.710981.
13. [13] Akkaya1 AV. Performance Analyzing of an Organic Rankine Cycle under different ambient conditions. Journal of Thermal Engineering 2017;3(5):1498-1504. https://doi.org/10.18186/journal-of-thermal-engineering.338897.