scholarly journals PERFORMANCE ENHANCEMENT FOR ROTARY AIR PREHEATER OF A THERMAL POWER PLANT

2020 ◽  
Vol 24 (06) ◽  
pp. 57-67
Author(s):  
Sinan Mazin Hazim ◽  
◽  
Mohammed H. Alhamdo ◽  
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Power Plant ◽  
Pressure Drop ◽  
Heat Transfer Rate ◽  
Thermal Power Plant ◽  
Transfer Rate ◽  
Thermal Power ◽  
Pumping Power ◽  
Air Preheater

The corrosion phenomenon is considered the main problems for air preheater in thermal power plant. The boiler flue gas contamination leads to decrease the air preheater performance and increases the maintenance cost, which causes the degradation of the cold end heating elements and thus leads to decrease the heat recovery rate. In this study, an experimental investigation was done for the transient thermal behavior and the pressure drop of the standard regenerative air preheater (Pmatrix) model, evaluating the performance factor, then modifying the air preheater (P+CG) model by changing the plates at the cold end last basket to the coarse gravel media. Since the gravel media have low thermal conductivity and predicted to give a high pressure drop, a new technique was done for the modified air preheater to compensate the low heat transfer rates and reduce the pressure drop in the gravel media by inserting bypass tubes at ratios (i and s), Which, the (i) model represents the inner aperture of tubes for the hot baskets facing to the inner aperture of tubes for the cold basket. While (s) model the insertion the tubes of the hot baskets as a staggered distribution with the tubes for the cold basket. The experimental investigation was carried out for the Reynolds number based on the test duct hydraulic diameter at a range of 24500<Re < 98000 for each charge and discharge periods. The experimental results are presented in terms of the average heat transfer rate and the pumping power for matrix models. The experimental measured results corroborated that the bypass tubes have a significant impact on improving the heat transfer rate and the pressure drop reduction of the modified air preheater matrix. The results showed that the best performance factor was achieved in the air preheater (P+CG+Ts) model which found to be in the range of 0.7-0.31 at high and low Reynolds. However, this improvement increased the pumping power by 13% than the (Pmatrix) model.

Study of Erosion and Accretion From Water and Steam Over Pipe Walls of Condenser in a Thermal Power Plant

2020 ◽  
Author(s):  
Eshwanth Asok ◽  
Karan Ashitbhai Shah ◽  
Jobaidur Rahman Khan
Keyword(s):  
Heat Transfer ◽  
Power Plant ◽  
Heat Transfer Rate ◽  
Thermal Power Plant ◽  
Transfer Rate ◽  
Thermal Power ◽  
Hard Water ◽  
Maximum Efficiency ◽  
Erosion Model ◽  
Erosion And Accretion

Abstract It is extremely important and required by thermal power plant to condense the exhaust steam from steam turbine outlets to obtain maximum efficiency on varying loads. Surface type condensers are often used to meet these demands. By condensing the exhaust steam at a pressure below atmospheric pressure, the pressure drop between inlet and outlet of turbine is increased which increases the amount of heat available for conversion to mechanical energy by the turbine. Increasing the heat transfer rate of condenser is an effective method to increase the overall efficiency of a thermal power plant. With condenser playing a vital role in overall plant efficiency, it is important to analyze the areas of fouling/erosion, which reduce the condensation rate. The condenser used in a company has been in operation for many years, so to study the effect of erosion on the condenser pipelines, a computational simulation of a section of the condenser in 210 MW thermal power plant with erosion modeling has been done using Fluent code. To help understand the steam cooling in the condenser, current study analyses a 3D section of the condenser used in a 210 MW thermal power plant using a commercial ANSYS/FLUENT code. A boundary layer coupled mesh is used to simulate the interaction of steam and water with the condenser tubes. Models to simulate the flow of water inside the tubes and low-pressure steam over the tubes are incorporated to show the heat transfer between the steam and water domain through the pipe walls along with incorporation of accretion and erosion model, specially the erosion. Analysis of erosion accretion due to Calcium salts are taken in consideration to interpret the location, where scaling happens and how the yearlong scaling affects the heat transfer ability of the heat transfer tubes. There is one build-in erosion and accretion model in FLUENT, which accounts of erosion/accretion on a surface from solid particle. Although the water is liquid, but the article that is responsible for erosion and accretion is solid, e.g. Calcium salt. The result shows that the heat transfer rate is not constant along the tube over a period due to erosion and untreated hard water used for cooling purpose. The Erosion model predicts the most prominent erosion/accretion sites inside the tubes and stresses on the importance of treatment of the recirculating hard water. A liquid particle erosion can also be modeled in future if needed.

Enhancement and Prediction of Heat Transfer Rate in Turbulent Flow Through Tube With Perforated Twisted Tape Inserts: A New Correlation

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
J. U. Ahamed ◽  
M. A. Wazed ◽  
S. Ahmed ◽  
Y. Nukman ◽  
T. M. Y. S. Tuan Ya ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Turbulent Flow ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Circular Tube ◽  
Twisted Tape ◽  
Pumping Power ◽  
Plain Tube ◽  
Flow Through

An experimental investigation has been carried out for turbulent flow in a tube with perforated twisted tape inserts. The mild steel twisted tape inserts with circular holes of different diameters (i.e., perforation) are used in the flow field. An intensive laboratory study is conducted for heat transfer and pressure drop characteristics in the tubes for turbulent flow with various airflow rates. Heat transfer and pressure drop data are engendered for a wide range Reynolds number (1.3×104–5.2×104). Tube wall temperature, pressure drop, air velocity, and its temperature are measured both for plain tube and for tube with perforated twisted tape inserts. Heat transfer coefficients, Nusselt number, pumping power, and heat transfer effectiveness are calculated for both cases. Experimental results showed that perforated twisted inserts of different geometry in a circular tube enhanced the heat transfer rate with an increase in friction factor and pumping power for turbulent flow. The pumping power, heat transfer coefficient, and effectiveness in the tube with the twisted tape inserts are found to increase up to 1.8, 5.5, and 4.0 times of those for the plain tube for same Reynolds number, respectively. Finally, a correlation is developed for prediction of the heat transfer rate for turbulent flow through a circular tube with perforated twisted tape inserts.

Experimental Research on Pressure Drop to Optimize Twisted Strips with Holes in Tubes of Condensers

2011 ◽  
Vol 347-353 ◽  
pp. 448-452
Author(s):  
De Qi Peng ◽  
Ya Jie Zhou ◽  
Wei Qiang Wang ◽  
Tian Lan Yu ◽  
Huan Yu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Power Plant ◽  
Pressure Drop ◽  
Flow Velocity ◽  
Experimental Research ◽  
Thermal Power Plant ◽  
Thermal Power ◽  
High Flow ◽  
Low Flow ◽  
High Flow Velocity

In order to reduce the pressure drop increase caused by self-rotating plastic twisted-strips in heat transfer tubes of vacuum condensers in thermal power plant, the twisted strips structure is optimized. There are holes distributed in twisted strip uniformly. The holes diameter and interval are optimized through experimental research. The results show that when holes diameter is less than 6mm, holes can reduce the pressure drop increase at low flow velocity while the pressure drop with holes is greater than that without holes at high flow velocity. The holes diameter is 4~5mm when the pressure drop is the lowest. The pressure drop with holes is always larger than that without holes when holes diameter is more than 6mm. The pressure drop will increase as holes interval decreases at high flow velocity, while it will reduce at low flow velocity.

scholarly journals Computational Analysis for Good Thermal Exchange and Low Pressure Drop in Regenerative Air Preheaters

2019 ◽  
pp. 1-15 ◽  
Author(s):  
P. C. Mioralli ◽  
M. A. B. Da Silva ◽  
E. Avallone ◽  
P. H. Palota ◽  
P. S. G. Natividade
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Computational Analysis ◽  
Convective Heat Transfer Coefficient ◽  
Low Pressure ◽  
Thermal Exchange ◽  
Air Preheater ◽  
Gas Streams

A computational analysis in a rotary regenerative air preheater subject to pre-established mass flow rate is performed. The heat transfer rate, the pressure drop and the outlet temperatures of gas streams are calculated from different matrix porosity values. The fluid flow and the convective heat transfer coefficient are determined from correlations. The total heat transfer is obtained using the Effectiveness-NTU method specific to regenerative air preheaters. Three typical regenerative air preheaters with both streams under the laminar flow regime are investigated. A range of porosity values that provide good thermal exchange and low pressure drop in the equipment is chosen for each examined air preheater. The behavior of the outlet temperatures of each gas stream as function of porosity is also analyzed. The results show that the porosity ranges shorten when the typical pressured drop values for each regenerative air preheater are introduced in the analysis. In addition, the behavior of the outlet temperatures is compatible with the behavior of the heat transfer rate as the porosity changes.

Pressure Drop and Heat Transfer Characteristics of Louvered Fin Heat Exchangers

2013 ◽  
Vol 465-466 ◽  
pp. 500-504 ◽  
Author(s):  
Shahrin Hisham Amirnordin ◽  
Hissein Didane Djamal ◽  
Mohd Norani Mansor ◽  
Amir Khalid ◽  
Md Seri Suzairin ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Transfer Rate ◽  
Heat Exchangers ◽  
Transfer Rate ◽  
Three Dimensional ◽  
Considerable Effect ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Louvered Fin

This paper presents the effect of the changes in fin geometry on pressure drop and heat transfer characteristics of louvered fin heat exchanger numerically. Three dimensional simulation using ANSYS Fluent have been conducted for six different configurations at Reynolds number ranging from 200 to 1000 based on louver pitch. The performance of this system has been evaluated by calculating pressure drop and heat transfer coefficient. The result shows that, the fin pitch and the louver pitch have a very considerable effect on pressure drop as well as heat transfer rate. It is observed that increasing the fin pitch will relatively result in an increase in heat transfer rate but at the same time, the pressure drop will decrease. On the other hand, low pressure drop and low heat transfer rate will be obtained when the louver pitch is increased. Final result shows a good agreement between experimental and numerical results of the louvered fin which is about 12%. This indicates the capability of louvered fin in enhancing the performance of heat exchangers.

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