Cooling Tower

Termodinamika sangat berharga untuk menganalisa sembarang sistem
yang melibatkan berbagai perpindahan energi; berbagai pemakaian
termodinamika yang praktis dan lazim dalam rekayasa adalah untuk
menganalisa berbagai sistem yang mengandung suatu zat kerja, biasanya
dalam fase cair atau gas, yang mengalir atau mendaur di dalam peralatan.
Dalam bab ini  berbagai karakteristik dari sejumlah sistem termodinamik akan
kita teliti, yang kebanyakan dari jenis yang baru disebutkan di atas dan
sebagai tambahan perilaku beberapa peralatan yang belum lazim tetapi
mempunyai prospek penggunaan praktis yang baik di masa depan akan kita
tinjau. Bebagai karakteristik ini dapat diprediksi dengan penggabungan
analisa termodinamika dengan pengalaman menjalankan perangkat keras.
Pada bagian lain akan ditinjau berbagai sistem yang cukup ideal sehingga
analisa performansinya masih tercakup oleh telaahan yang sudah dilakukan
hingga kini.
Berbagai sistem yang menjadi pusat perhatian disini adalah sistem
refrijerasi atau pendingin yang ingin dicapai untuk mempertahankan agar
suatu ruang tetap dingin dengan mengeluarkan energi sebagai panas secara
berkesinambungan dari ruang tersebut. Kebanyakan sistem tersebut
melibatkan suatu fluida kerja, seperti air atau udara, yang disirkulasikan
melalui sistem dalam suatu daur. Hukum kedua termodinamika menerapkan
berbagai batasan yang ketat terhadap performansi berbagai sistem
perpindahan termal dan perihal ini akan diteliti dalam berbagai uraian berikut.
Bidang temperatur entropi mempunyai peran yang penting; apabila zat
mengalami suatu proses reversibel, urut-urutan tingkat keadaan yang dilalui menggoreskan suatu garis (kurva) dalam bidang T-s. Karena proses
reversibel, perpindahan energi sebagai panas ke satu satuan massa zat
diwakili oleh luas di bawah kurva pada bidang T-s. Apabila zat mengalami
proses daur, tidak terdapat perubahan energi dalam netto untuk suatu daur,
jadi perpindahan energi netto ke satu satuan massa zat sebagai panas
selama daur berlangsung harus sama dengan perpindahan energi netto
sebagai kerja dari zat (kerja yang dilakukan), dan keduanya sama dengan
luas yang terkurung oleh lintasan reversibel dalam bidang T-s (Gambar 9.4).
Jadi, pernyataan proses T-s dapat digunakan sebagai perangkat grafik untuk
membandingkan dan menilai berbagai sistem termodinamik dan perangkat ini
akan digunakan secara ekstensif di dalam bab ini. Berbagai bidang
termodinamik lainnya juga sangat memperikan seperti nanti akan terlibat.

The performance of a forced draft wet cooling tower was investigated experimentally and the calculation was performed by appl ying second law of thermodynamics (exergy analysis). The mathematical model was developed by using engineering equation solver (EES) software. The results show that the chemical exergy of air increases from the bottom to the top of the cooling tower, the thermal exergy of air decreases from bottom to the top of the cooling, the exergy of water decreases from top to the bottom of the cooling tower. The exergy destruction decreases from bottom to the top of the cooling tower, and the exergy efficiency decreases from top to the bottom of the cooling. The exergy destruction tends to increase as the inlet wet bulb temperature increases while the exergy efficiency decreases. As water-air flow rate ratio increases the exergy destruction increases while the exergy efficiency decreases. The results show that t here is an inverse proportional between exergy destruction and exergy efficiency.

In this paper, the development of natural draft cooling towers diagnostics is presented. Diagnostic method is based on measurements of velocity and temperature fields of the airflow in the entire surface area of cooling tower and the raised phenomenological model of heat and mass transfer in a selected reference vertical segment of cooling tower. Velocity and temperature fields of the

Legionnaires disease or legionellosis arose due to human alteration of the environment, Legionella species can be found in aquatic environments, water warm and hot, and humid places, such as cooling towers, spas, among others. This is an infectious disease caused by bacteria belonging to the genus Legionella. To reduce the multiplication of Legionella pneumophila and the associated risk of Legionnaires' disease should be taken measures to prevent and control physical, chemical and microbiological, in order to promote and maintain clean surfaces of water systems and air. One of the systems used for purification of air filtration consists in the separation and capture of particles of any kind. The filters need technical requirements that are a balance between three key parameters: the filter efficiency, pressure drop and the durability of the filter.

This paper presents an experimental and numerical investigation of the thermal performance of natural draft wet cooling tower (NDWCT). The experimental investigation is carried out under natural draft condition and forced draft condition created by an axial fan. The operational parameters considered in this study are the thickness of the fill (10 and 20 cm), inlet water temperature (40, 45, and 50 °C) and inlet water volume flow rate (5.68, 7.75, and 9.46 L/min). The experimental results showed that the thermal performance is improved when the fans are used with the NDWCT. The temperature difference between inlet and outlet and effectiveness increase by 35% and 37.2%, respectively at fill thickness of 20 cm and water volume flow rate of 11.35 L/min. The temperature distribution of the air and the relative humidity were numerically simulated for both cases of natural and forced draft by employing the commercial CFD software ANSYS Fluent 15. The experimental and numerical results were validated with results from a previous work and showed a good agreement. The experimental results showed that the effectiveness increase by 22% and 30% for NDWCT and FDWCT respectively when in case of fill thickness 20 cm.

— Cooling towers are one of the biggest heat and mass transfer devices used to transfer process waste heat to the atmosphere. Cooling towers make use of evaporation whereby some of the water is evaporated into a moving air stream and subsequently discharged into the atmosphere. As a result, the remainder of the water is cooled down significantly. The process parameters such as inlet Air Wet bulb Temperature, Flow rate of Water and fills porosity have more influence on Thermal performance of cooling tower. The Temperature of outlet water is maintained nearest to inlet air wet bulb temperature to obtain the best Thermal Performance of cooling tower. Finite element method is one of the powerful numerical techniques to solve the complex physical phenomenon that are governed by the differential equations. Many of the practical engineering problems such as structural, thermal, magnetic, acoustic, etc. can be solved by the finite element method. Moreover, the finite element method is an increasingly common tool for engineering design. Design and dimension are taken from Dishman Pharmaceutical And Chemical Limited,Naroda GIDC, Ahmedabad, Gujarat. In this research work my objective is to get optimum condition which gives the maximum effectiveness in counter flow FRP cooling tower. For effectiveness parameters like inlet water flow rate, inlet air rate and fill porosity are considering in this research. So optimization of heat transfer is done by using taguchi method. Taguchi method is reducing the number is experiment. Here also used the Minitab software for taguchi method. For this model of cooling tower is made in Creo 2.0 then convert this model in STEP file and imported in ANSYS Workbench for CFD analysis. In this paper present the CFD analysis of cooling tower and comparing this result to practical reading. For taking practical reading temperature sensor and thermocouple is used.

In this work, the feasibility of using cooling towers has been studied theoretically for thermal power plants located in tropical region. Since cooling tower is directly coupled with the condenser of a power plant, the impact of selection of cooling tower on the design of condenser has been assessed. Electrical output of the plant is taken 1200í µí±€í µí±€í µí±€í µí±€ í µí±’í µí±’ and thermal efficiency is taken nearly 60% after superheating, thus around 800í µí±€í µí±€í µí±€í µí±€ í µí±¡í µí±¡ thermal load has been assumed on the condenser. The tertiary coolant water inlet temperature is assumed 28 0 C which is the normal reservoir temperature in tropical regions. Condensers with both single and multiple shell tanks have been studied. Design feasibility was evaluated based on two parameters; tube-side flow velocity and length to shell diameter ratio. From the results, it may be observed that there is no preferable design option for condensers with single shell tank and 2 shell tank, both for with and without cooling tower. For condensers with 3 and 4 shell tanks, multiple preferable design options were obtained. The number of design options is lower for condenser with cooling tower compared to the ones without cooling tower. Also, condenser size is found to be much larger for condensers with cooling towers than without cooling towers. As a result, use of cooling tower is not recommended.

Green roofs have been proposed for energy saving purposes in many countries with different climatic conditions. However, the energy saving potential of green roofs depends on several aspects, such as the climate characteristics or the building loads. For this reason, the authors have been working on ways to modify the thermodynamic behavior of green roofs through passive low energy systems operating according to rules based on the relationships between the indoor and outdoor temperatures. This paper discusses the improvements in indoor thermal comfort which can be obtained by adopting water-to-air heat exchangers and indirect evaporative and radiant cooling strategies in buildings with green roofs. The study specifically looks at the effect of combining a simple evaporative/radiant system that cools the water pond where the water-to-air heat exchange occurs. Ad-hoc built test cells were investigated in southern California for over a year. Overall, the water-to-air heat exchangers proved to cool the indoor air in the test cells by almost 10 • C when the exterior temperatures were above 35 • C. In this system, the heat from the interior of the cells that could not be absorbed by the green roof, was transferred to the coupled water sink, and then dissipated into the atmosphere. This study shows that the benefits of the water-to-air heat exchange and of the evaporative cooling system are promising, while the water consumption is limited. Finally, the experimental investigation summarizes the benefits of combining green roofs and evaporative and radiant cooling of a water-to-air heat exchanger as a solution for building cooling and proposes simple equations to anticipate their temperature cooling effects.

Biofilm formation in recirculating water systems such as cooling towers lead to many undesired conditions in terms of public health concern, operational damage and economic loss. Accumulation of pathogenic bacteria (i.e. Legionella pneumophila), increased resistance to antimicrobial compounds, a significant energy loss by increasing heat transfer resistance, equipment damage through microbiologically influenced corrosion (MIC) and premature replacement of equipment constitute some of the important adverse effects of biofilm. To eliminate or reduce the biofouling problem various mechanical and chemical methods are used. The most common approach is chemical treatment primarily using biocides, since mechanical methods have disadvantages due to application difficulties, economical losses because of the system closure during applications and above all the risk of transmission of pathogens. Manufacturers recommend a variety of biocides and concentrations for decontamination recirculating water systems, however, these recommendations are not suited for every system and target microorganisms. To establish a successful biocide program in full scale systems, it is necessary to evaluate the antibacterial activity of correct biocide and/or combinations against both planktonic and sessile bacteria in terms of dosage and contact times in laboratory conditions with taking into consideration of important issues. Thus, the minimum amount of biocide which is necessary for biofouling control will be used and that will not affect either the environment or the performance of the plant itself adversely. In this review, important considerations for accurate evaluation of antibacterial activity will be highlighted.

Three essential, interacting components of geoengineering are explored in some detail -- (1) superheated water vapor from power plant cooling towers; (2) chemtrails consisting of heavy metals, endocrine disrupters, nanotechnology, as well as  bioengineered materials; and, (3) nexrad Doppler radar facilities.

Cooling towers make use of evaporation whereby some of the water is evaporated into a moving air stream and subsequently discharged into the atmosphere. As a result, the remainder of the water is cooled down significantly.The process parameters such as inlet air rate, water flow rate and fills porosity have more influence on Thermal performance of cooling tower. The Temperature of outlet water is maintained nearest to inlet air wet bulb temperature to obtain the best Thermal Performance of cooling tower. So current work is to obtain and maintaining outlet water Temperature nearest to inlet air wet bulb temperature. The cooling tower fill is the most critical component in the operation of the cooling tower. The function of the tower fill is to provide a maximum contact surface between the water and the air to promote evaporation and heat transfer. Cooling tower fill accelerates the transfer of heat from circulating water by maximizing the contact area between water and air. So inlet water flow rate, inlet air rate and fill porosity are important factor to maintain the outlet temperature of water nearest to inlet air wet bulb temperature.

In this study a model cooling tower system was experimentally infected by L. pneumophila ATCC 33152 and has been run to the nearest operating conditions of full-scale system. Effectiveness of colloidal silver-hydrogen peroxide biocide was assessed against both planktonic and bio¿lm bacteria (on stainless steel, glass, polyvinyl chloride slides) monthly during 6 months experiment period. Each month, samples were analyzed for heterotrophic plate count (HPC), the presence of Legionella spp., viable and total counts, the total and free ATP concentration. A considerable variation was found in the response of biofilm to the biocide when biofilm reached the mature phase (from the 4 th month). The reduction to zero in HPC values, from the 2 nd and 5 th month in planktonic and biofilm phase, respectively; has been interpreted as induction of the viable but non-culturable form state in bacteria. The results emphasized that biocide should be applied on a regular basis prior to the settlement of pollution in the system and microbial burden monitoring/data evaluation should be done periodically by using different microbiological techniques for the proper evaluation of the system.

The mass transfer coefficient for a cooling tower is determined experimentally and
theoretically. Contribution of a diffusion and convection component into mass trans­
fer is estimated. The assessment showed that the contribution of the convection com­
ponent into mass transfer can be neglected.
Thickness of the diffusion layer was experimentally measured and compared
with the theoretically obtained hydrodynamic displacement layer. The calculation of
the mass transfer coefficient uses the displacement layer. It is demonstrated that the
difference between experimental data and simulation results does not exceed 33% in
the range of air velocity of (1.3–3.0) m/s.

This paper deals with an experimental analysis of simultaneous heat and mass transfer phenomena between water and air by direct contact in a packed cooling tower. The tower is filled with a “VGA.” (Vertical Grid Apparatus) type packing. The packing is 0.42 m high and consists of ...

This paper presents a model-based optimization strategy for the condenser water loop of centralized heating, ventilation and air conditioning (HVAC) systems. Through analyzing each component characteristics and interactions within and between cooling towers and chillers, the optimization problem is formulated as that of minimizing the total operating cost of all energy consuming devices with mechanical limitations, component interactions, outdoor environment and indoor cooling load demands as constraints. A modified genetic algorithm for this particular problem is proposed to obtain the optimal set points of the process. Simulations and experimental results on a centralized HVAC pilot plant show that the operating cost of the condenser water loop can be substantially reduced compared with conventional operation strategies.