FIELD MEASUREMENT AND NUMERICAL STUDY OF EXTERNAL WIND PRESSURE OF RIBBED COOLING TOWER

The hyperbolic thin-shell cooling tower is a typical wind-sensitive structure. The full-size measurement is the most direct and important way to study the distribution of wind pressure on the surface of the cooling tower. Due to the limitations of engineering conditions and meteorological conditions, the field measured data are relatively lacking, and the field test data of ribbed cooling towers are less. In order to analyze the wind pressure distribution on the surface of the cooling tower, we chose a ribbed cooling tower in Toksun County, Xinjiang, China, where there are strong winds all year round, and field measurements were carried out to understand the wind load characteristics of the tower under the perennial dominant wind direction and the maximum wind direction. It was found that the absolute value of the negative pressure on the leeward side was larger than that in the code and the fluctuating wind pressure coefficient fluctuates greatly when the field measured wind speed was greater than 10m/s (15 meters above the ground). For circular section cooling tower, the Reynolds number (Re) has great influence on wind pressure. With the increase of Re, the absolute value of the average negative pressure of the tail wind pressure coefficient increases, which should be paid attention to in design. The regression curves of the average wind pressure coefficients measured on site under several typical working conditions are given by using the least square method, and its form is consistent with the standard (but the coefficients are different). In addition, Fluent software was used to calculate the external wind pressure of the cooling tower, and the field measured results were compared with the Chinese code, German code and numerical calculation, and the results were consistent.

ANALISIS TEMPERATUR LINGKUNGAN TERHADAP KINERJA COOLING TOWER DI PT. INDOCEMENT TUNGGAL PRAKARSA TBK. P-12 TARJUN KALIMANTAN - SELATAN

Sistem kerja pendingin di PT. Indocement Tunggal Prakarsa Tbk Tarjun Plant-12 menggunakan cooling tower marley fan 3 tipe mechanical draft, counterflow flow 10.221 m3/h yang berfungsi untuk mendinginkan air keluaran dari kondensor melalui nozzle untuk menyemprotkannya dengan menyemprotkan sebagian air ke udara dan mengeluarkannya ke atmosfer, sehingga air jatuh ke bak air melalui eliminator melayang. Suhu lingkungan mempengaruhi kinerja menara pendingin. Semakin dingin lingkungan semakin baik kinerja menara pendingin. Pengaruh suhu lingkungan dan kinerja pada menara pendingin menjadi pembahasan dalam penelitian ini. Hasil perhitungan dalam penelitian menunjukkan bahwa suhu lingkungan mempengaruhi kinerja menara pendingin dimana pada pagi sampai sore hari pada suhu atau cuaca tertentu kinerja menara pendingin mengalami peningkatan dan penurunan yang signifikan. Sedangkan efisiensi rata-rata range dan approach dari tahun 2016 hingga 2019 mengalami penurunan efisiensi sebesar 8,44%, penurunan range sebesar 1,24°C dan penurunan approach sebesar 0,82°C. Cooling work system at PT. Indocement Tunggal Prakarsa Tbk Tarjun Plant-12 uses a cooling tower marley fan 3 type mechanical draft, counterflow flow 10.221 m3 / h which functions to cool the output water from the condenser through a nozzle to spray it by spraying some water into the air and discharging it into the atmosphere, so water falls into the water basin through a drift eliminator. Environmental temperature affects the cooling tower performance. The cooler the environment the better the cooling tower performance. The effect of environmental temperature and performance on cooling tower is the discussion in this study. The results of calculations in the study show that the environmental temperature affects the cooling tower performance where in the morning until late afternoon at certain temperatures or weather the cooling tower performance experiences a significant increase and decrease. While the average efficiency, the range and approach from 2016 to 2019 has decreased efficiency by 8.44%, decreasing the range by 1.24 ° C and decreasing the approach by 0.82 ° C.

Performance Evaluation of a Maisotsenko Cycle Cooling Tower with Uneven Length of Dry and Wet Channels in Hot and Humid Conditions

The use of the Maisotsenko cycle (M-Cycle) in traditional wet cooling towers (TWCTs) has the potential to reduce the costs of electricity generation by cooling water below the inlet air’s wet-bulb temperature. TWCTs cannot provide sufficient cooling capacity for the increasing demand for cooling energy in the power and industrial sectors—especially in hot and wet climates. Due to this fact, an experimental system of an M-Cycle cooling tower (MCT) with parallel counter-flow arrangement fills was constructed in order to provide perspective on the optimal length of dry channels (ldry), thermal performance under different conditions, and pressure drops of the MCT. Results showed that the optimal value of ldry was 2.4 m, and the maximum wet-bulb effectiveness was up to 180%. In addition, the impact of air velocity in wet channels on the pressure drops of the novel fills was also summarized. This study confirms the great potential of using the M-Cycle in TWCTs, and provides a guideline for the industrial application and performance improvement of MCTs.

Non-equilibrium thermal fluctuations of flow in thermal systems

Fouling is detrimental to the heat transfer performance of concentrated solar power (CSP) plant components where heat exchange takes place with the cooling tower water. Wave elements cause an expression of deep insight of the fouling formation. A wave element is the wave interface between two molecule groups with different temperatures in flow; it is generated by density difference, which results from temperature difference. Tiny temperature differences always exist everywhere in a fluid. When a fluid is in motion, wave elements are generated among molecule groups. Wave motion and Brownian motion can be the two basic forms of motion of the molecules in flow. Temperature controls Brownian motion. Temperature differences and the fluid's motion cause the wave elements. Non-equilibrium thermal fluctuations present as wave elements in a flow. A wave element appears as wave behavior along the space and time dimensions that are based on the continuity relation. The direct experimental evidence for wave elements cannot be directly established at the present scientific testing capability because the temperature difference of two molecule groups adjoining each other in a flow is infinitesimal. A series of “enlarged size” experiments are conducted involving the cooling tower water fouling to show the wave elements' behaviors by tracing the molecules' movement. The experimental study presents that the wave interface along the space and time dimensions simultaneously exists between two densities due to fluid motion. The experimental evidence and theoretical analysis support each other.

A Novel Optimized Formulation for Cooling Tower Effluent Disinfection: Tarasht Power Plant Case Study

Since the operating conditions of the cooling tower units provide such a suitable environment for the growth of bacteria and algae, taking measures for the disinfection process is strongly recommended. The cooling tower unit is proceeded by RO and the disinfection strategy is sodium hypochlorite, combined with this new formulation. The sampling result revealed that bacteria counts from the effluent of the cooling tower are 2600 CFU/ml while the microbial load of the water in the pond is 220 CFU/ml. Herein, two type formulations are introduced for cooling tower output stream while the pond water comes along with a NaOCl injection. The dosage of A: Glucose Oxidase, B: ammonium persulfate, and C: Amoxicillin, and D: the order of use are chosen as the four independent variables whose effects and their binary interactions on microbial load and disinfection efficiency were investigated via Box–Behnken design (BBD) combined with response surface methodology (RSM). The ANOVA results show that the most significant variable is amoxicillin in the presence of bleach. Meanwhile, high values for R2 > 0.99 and the model F-value 45.64 in addition to diagnostic tests confirmed the reliability of the model. Several solutions have been introduced as optimum formulations. The pre-scale up and economic considerations have been included.