Heat rejection enhancement in natural draft cooling tower using radiator-type windbreakers

Goodarzi, M.; Keimanesh, Reza

doi:10.1016/j.enconman.2013.03.031

Cited by 97 publications

(27 citation statements)

References 17 publications

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“…Al-Waked et al [15] introduced windbreak walls around the tower inlet, by which the thermal efficiency is improved by 15% and 35% under crosswinds of 10 and 20 m/s respectively. Goodarzi and Keimanesh [16,17] studied the radiator-type windbreakers and Savonius turbines installed at the lateral heat exchanger bundles normal to the incoming winds, which are superior to the solid windbreakers. Lu et al [18][19][20] investigated windbreakers with tri-blade-like configuration installed at the small tower inlet to improve the heat capacity of cooling air.…”

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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Section: Introductionmentioning

confidence: 99%

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

et al. 2017

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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%

“…Goodarzi [85] proposed that the air-cooled heat exchangers can be used to acting as the windbreak walls (radiator type windbreakers as the authors called). Since these heat exchangers functions as both windbreak wall as well as the extra heat transfer unit, the performance of the cooling tower is found to be better than applying solid windbreak wall.…”

Section: Combined Windbreak Wallmentioning

confidence: 99%

“…M. Goodarzi explored the influence of the shell geometry on the cooling tower performance at various crosswinds. [117,183] In his research, alternative shell geometry with elliptical cross section was proposed instead of usual shell geometry with circular cross section. At crosswind speed of 10m/s, the cooling tower with this special shell geometry could have the same thermal performance as the cooling tower with windbreak walls.…”

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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“…Small NDDCTs have not yet gained widespread use largely due to concerns that negative cross-wind effects would be detrimental to performance at this small scale. However there have been a number of numerical and experimental studies showing methods to minimise and even reverse this problem (Goodarzi, 2010;Goodarzi & Keimanesh, 2013;Y. Lu et al, 2013;Y.…”

Section: Nddct Overviewmentioning

confidence: 99%

Design optimisation of an Australian EGS power plant using a natural draft dry cooling tower

Duniam¹

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Enhanced Geothermal Systems (EGS) technology was successfully demonstrated in theAustralian context with the operation of the Habanero 1MW pilot plant. This project aims to determine the optimum power plant design for the geothermal parameters found at the Habanero pilot plant. In order to achieve this, a techno-economic optimisation of an Organic Rankine Cycle (ORC) was undertaken.The EGS conditions used in this work are a brine production well head temperature of 220 o C, and minimum brine temperature of 80 o C in order to limit scaling formation in the brine heat exchanger(s). The production well head pressure is 35 MPa and the required reinjection pressure is 45 MPa in order to maintain the desired mass flow rate of 35 kg/s through the EGS resource.A significant source of parasitic power consumption in ORC systems occurs in the condensing system. In order to avert this parasitic power consumption Natural Draft Dry Cooling Towers (NDDCTs) were investigated as the condenser for the ORC. A one dimensional NDDCT model was developed and integrated into the cycle design process to analyse and design for the coupled nature of NDDCT performance with the power cycle. As a base for comparison a one dimensional Mechanical Draft Air Cooled Tower (MDACT) model was developed and each cycle was also analysed with MDACT as the condenser.A wide range of organic working fluids and several cycle configurations were evaluated in the preliminary analysis using a simplified NDDCT model. The cycles were optimised for maximum net power generation and the highest performing cycle configurations were progressed to the techno-economic design point optimisation stage. The cost of each of the major equipment items in the plant was estimated using cost correlations based on historical equipment cost data. The condensing system geometry for both NDDCT and MDACT, heat exchanger geometry and cycle parameters were optimised to find the lowest Specific Investment Cost (SIC) in AUD/kWe for each candidate cycle. The cycle configurations with the lowest SIC from the design point analysis were evaluated across the range of ambient temperatures expected at the site. The mean annual net power generation for each cycle was calculated based on site temperature data and this was used in determining the annualised SIC values, the measure by which the optimum plant configuration was selected. IIThe recuperated, regenerative and basic ORCs were found to be the cycles that obtained the highest net power generation in the preliminary analysis with butane, butene, isobutene, R152a, isobutane, R123 and isopentane the highest performing fluids. The highest net power generation found in the preliminary analysis was 2.688 MWe.The NDDCT model developed in IPSEpro was investigated in isolation to find the optimum design configuration which gives the lowest SICcd, in AUD/kWth of heat rejected. The tower geometry ratios selected were: aspect ratio (tower height / base diameter) of 1.4, diameter ratio (outlet diameter / base diameter) of 0.7, and / 3 (the p...

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Heat rejection enhancement in natural draft cooling tower using radiator-type windbreakers

Cited by 97 publications

References 17 publications

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

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

Design optimisation of an Australian EGS power plant using a natural draft dry cooling tower

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