Effects of ambient temperature and crosswind on thermo-flow performance of the tower under energy balance of the indirect dry cooling system

Ma, Huan; Si, Fengqi; Li, Lan; Yan, Wensheng; Zhu, Kangping

doi:10.1016/j.applthermaleng.2014.12.048

Cited by 69 publications

(43 citation statements)

References 10 publications

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“…And finally the evaporation rate of water in this type of towers is lower than wet cooling towers. Thereafter Ma et al (2015) surveyed the effect of both the ambient temperature and cross wind on efficiency of cooling towers. They concluded that effect of outlet water temperature has non-linear and linear relationship with the wind velocity and the ambient temperature respectively.…”

Section: Introductionmentioning

confidence: 99%

Thermo-economic study of hybrid cooling tower systems

Parsa¹,

Shokouhmand²,

Sattari³

et al. 2016

Int. J. Phys. Sci.

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In this paper, the effects of ambient temperature and relative humidity on performance of wet, dry, and two combined cooling systems are studied for a typical 250 MW power plant in Hamedan, Iran. Although there have been many works in background of effects of different parameters on performance of cooling towers, there is no detail analysis about different alternatives of hybrid cooling systems due to the water consumption. In this study, four alternatives were considered for the cooling system: wet, dry, and two combined wet and dry cooling systems. One of the hybrid systems demanding only half of the cells of the existing wet cooling system so has a limitation for water consumption. Another one has no limitation for utilizing all of the cells of the existing wet cooling towers and as a result does not have any limitation for water consumption. Investigating mentioned cases are significant due to the lack of water in middle-east countries. Also, by means of monthly profiles of ambient temperature, the amount of annual power loss is computed for each case. The water consumption for each case, is computed as well. Finally, the best alternative was determined by computing both the capital and annual costs, and annual water consumption.

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Section: Introductionmentioning

confidence: 99%

Thermo-economic study of hybrid cooling tower systems

Parsa¹,

Shokouhmand²,

Sattari³

et al. 2016

Int. J. Phys. Sci.

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“…With the CFD method, Yang et al [3] studied the wind effects and obtained the thermo-flow performances of air-cooled heat exchanger. Ma et al [4] developed the cold end system, namely a coupled NDDCS and steam condenser model, so as to control the outlet water temperatures of NDDCS precisely versus various wind speeds and ambient temperatures. With specific experiments, Lu et al [5] explored the crosswind effects on a small cylindrical natural draft dry cooling tower, pointing out the critical wind speed which incurs the most adverse thermo-flow performances.…”

Section: Introductionmentioning

confidence: 99%

Performance Recovery of Natural Draft Dry Cooling Systems by Combined Air Leading Strategies

et al. 2017

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Abstract:The cooling efficiency of natural draft dry cooling system (NDDCS) are vulnerable to ambient winds, so the implementation of measures against the wind effects is of great importance. This work presents the combined air leading strategies to recover the flow and heat transfer performances of NDDCS. Following the energy balance among the exhaust steam, circulating water, and cooling air, numerical models of natural draft dry cooling systems with the combined air leading strategies are developed. The cooling air streamlines, volume effectiveness, thermal efficiency and outlet water temperature for each cooling delta of the large-scale heat exchanger are obtained. The overall volume effectiveness, average outlet water temperature of NDDCS and steam turbine back pressure are calculated. The results show that with the air leading strategies inside or outside the dry-cooling tower, the thermo-flow performances of natural draft dry cooling system are improved under all wind conditions. The combined inner and outer air leading strategies are superior to other single strategy in the performance recovery, thus can be recommended for NDDCS in power generating units.

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“…Based on Hooman's theory, Ma et al [87,88] proposed a theoretical model to consider both the impacts of ambient temperature and crosswind. They also considered the initial temperature difference since this parameter have a significant effect on the vertical air velocity of the cooling tower under windless condition.…”

Section: Eq (2-21)mentioning

confidence: 99%

“…Short-NDDCTs, which can effectively discharge heat and do not consume any water and electricity, are likely to be a feasible cooling technology for these kinds of power plants [5,27] . Past studies have identified the vulnerability of short natural draft towers to ambient influences, especially the crosswind and the hot ambient temperature [6,34,39,129]. This paper describes the simulated performance of a 20 m tall experimental NDDCT constructed at the University of Queensland.…”

Section: Introductionmentioning

confidence: 99%

“…They found the windbreak walls enhancing the performance of the cooling tower at certain wind speeds. Ma et al [87,113] studied the angles of the windbreak wall for a NDDCT with vertical heat exchanger. Their research found that the optimized walls can reduce the interference on airflow at low wind speeds and create a strong secondary flow at high wind speeds.…”

Section: Introductionmentioning

confidence: 99%

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Numerical and experimental study of small natural draft dry cooling tower for concentrating solar thermal power plant

Li¹

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The typically arid climates in the likely locations for renewable thermal power plants such as Concentrating Solar Thermal (CST) power plants provide the motivation for dry cooling technology applications. Natural draft dry cooling tower (NDDCT) with low maintenance cost and no parasitic power consumption offers a feasible and cost effective option for such applications. Compared with the conventional coal fired and nuclear power plants, the size of the CST power plant proposed for Australian regional communities is much smaller. However, the existing cooling tower design is optimised for large steam power plants, and is not optimal for these renewable power plants. (2) The performance of the experimental tower was tested at two constant heat loads of 600 kW and 840 kW, respectively, with various ambient temperatures. The 1D numerical model was refined and validated with the experimental data. The thermodynamic model of a 1 MW CST power plant running with sCO2 cycle was developed and integrated with the updated cooling tower model. Significant differences were observed between the steam Rankine and sCO2 cycles in terms of the effect of the ambient temperature on power generation. The differences between steam Rankine and sCO2 Brayton cycle in this context were analysed and discussed.(3) Two potential cooling issues with small NDDCT, the crosswind and the cold inflow, were identified and the detail experimental data were presented. The crosswind effect on small cooling tower is different from the conventional big cooling towers. With the increase of the crosswind speed, the overall cooling performance of the small NDDCT first decreases and then increases. The mixed convection theory and the Richardson Number were proposed to explain this phenomenon. On the other hand, repeated cold inflow events were observed during the tests, which cause a significant decrease of the air temperature inside the cooling tower. The water outlet temperature can be increased up to 3°C as a result of the cold inflow effect. Further analysis of the mechanism shows that the cold air incursion at the top of the cooling tower could decrease the driving force and also form an extra flow resistance for the airflow through the heat exchanger.(4) Based on the working mechanism of the air-cooled heat exchanger and the crosswind effect on NDDCT, this study proposed a new method to increase the cooling performance of NDDCT under crosswind conditions by optimizing the water mass flow rate in the air-cooled heat exchangers. By optimising the water distribution, the water outlet temperature of each heat exchanger is more uniform and the adversely influence of the crosswind can be effectively relieved.The findings in this paper can lay an important foundation for future small cooling tower design and operation.

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Effects of ambient temperature and crosswind on thermo-flow performance of the tower under energy balance of the indirect dry cooling system

Cited by 69 publications

References 10 publications

Thermo-economic study of hybrid cooling tower systems

Thermo-economic study of hybrid cooling tower systems

Performance Recovery of Natural Draft Dry Cooling Systems by Combined Air Leading Strategies

Numerical and experimental study of small natural draft dry cooling tower for concentrating solar thermal power plant

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