Improving cooling efficiency of dry-cooling towers under cross-wind conditions by using wind-break methods

Zhai, Zhiqiang; Fu, Song

doi:10.1016/j.applthermaleng.2005.10.016

Cited by 135 publications

(64 citation statements)

References 7 publications

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“…Since the crosswind could significantly hinder the performance of the heat exchanger located at the lateral sides of the cooling tower by blocking the air pass through the heat exchanger, the simplest way to solve this problem is to place the windbreak wall at lateral sides of the tower, as shown in Figure 2-20(a). This method has been investigated by Zhai [46] and Goodarzi [85]. The cooling performance was reported to be increased by 50% after applying the windbreak wall.…”

Section: External Windbreak Wallmentioning

confidence: 99%

“…In the isothermal tests [44][45][46][47][48], the densimetric Fr is neglected and the natural draft effect is modelled by using mechanical fans. The mechanical fans can be installed at the top of the cooling tower, at the throat of the cooling tower or at the bottom of the cooling tower.…”

Section: Lab-scale Model Measurementsmentioning

confidence: 99%

“…However, most of previous full scale experimental studies of the crosswind effect didn't provide enough details, such as the detailed experimental data of wind direction, changes in ambient temperature, detailed heat exchanger temperature and the air temperature distribution within the cooling tower [4,45,99,132,159]. On the other hand, the experiments on lab-scale cooling tower models can offer controlled conditions and reliable data, but most of the Reynolds numbers for such small towers are much lower than those for full scale towers, which may result in erroneous results [4,41,42,46,156]. In addition, most of the lab-scale cooling towers used electrical heaters or mechanical fans to simulate the aircooled heat exchanger in the test model, which could also make the outcomes inaccurate.…”

Section: Introductionmentioning

confidence: 99%

“…A great deal of experimental research has already been published on the cooling performance of tall [46] discussed the wind-break wall method on NDDCT using both experimental investigation and computer simulation. The experimental scale is 1/640 of the prototype.…”

Section: Introductionmentioning

confidence: 99%

“…According to their result, the A-frame and radially patterned heat exchanger layout could reduce the negative effect of the crosswind. Zhai and Fu [46] tested the performance of the windbreak wall in and around a small scaled cooling tower in the wind tunnel. The relationship between the cooling efficiency recovery and the size of windbreak walls was analysed.…”

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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Section: External Windbreak Wallmentioning

confidence: 99%

Section: Lab-scale Model Measurementsmentioning

confidence: 99%