Browsing by Author "Srinivasan, P."

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CFD Analysis of Air Cooled IC Engine Fins in the Presence of an Obstruction Placed Upstream at Low Ambient Temperatures
(Begell House, 2021) Srinivasan, P.
The present work aims to address the issue of overcooling at low ambient temperatures in air-cooled IC engines that use fins for heat transfer augmentation. A design modification is proposed to reduce excess cooling at low temperatures in comparison to the heat flux at room temperature. An arc-shaped obstruction placed upstream to the fin, is used to reduce the heat transfer. Two dimensional computational fluid dynamics analysis using ANSYS Fluent is used to study the effect of the obstruction on the heat transfer coefficient of the fin at various velocity conditions for different geometric parameters of the arc. A relationship between the design parameters of the obstruction arc and the heat transfer coefficient is obtained, from which it is observed that the over-cooling can be significantly reduced at certain design parameters of the arc.
CFD Based Study of Gas Turbine Blade Cooling
(Springer, 2023-03) Srinivasan, P.
Over the years, many techniques have been employed to improve the aerothermal efficiency of gas turbines. The hot gases inlet temperature greatly affects the work output and therefore, efficiency of the turbine. To overcome the metallurgical constraints associated with maximum blade temperature, different methods have been devised to keep it under the permissible levels. The current thesis explores convective cooling of the blades by the means of internal passages. Other methods like ceramic blades have their own limitations in terms of brittle failure, and thermal barrier coatings are almost always used in conjunction with convective cooling. Conjugate heat transfer (CHT) simulations have been performed on a 65 mm gas turbine blade section with cooling cavity, using ANSYS CFX 2019 FVM solver. Cooling performance and pressure loss characteristics of the cavity have been analysed by increasing number of protrusions on the cavity walls from 0 to 88. The results and plots suggest that an increase in the coolant advection causes a reduction in blade maximum temperature, but the temperature reduction obtained with successive velocity increments follows a diminishing trend. However, the pressure loss associated with the coolant flow follows an increasing trend with increasing slope. Increment in the number of protrusions results in a similar trend, with successive addition of protrusions resulting in greater rise in coolant pressure loss.
Comparing Environmental Impact of Various Energy Sources Powering Data Centres’s at Indian Candidate Locations
(Springer, 2021-08) Srinivasan, P.
While major 21st century developments are data-intensive, the use and storage of such high volumes of data are processed through datacentres. Though Datacentres (DC) are typically high-power consumption applications, the percentage of energy consumption is even higher in developing economies such as India. This paper studies the net environmental impact of energy supply to such datacentres, at four candidate locations, by examining their net Green House Gas Emissions per kWh and land usage per kW. The study analyses various sources of energy such as thermal, wind, and solar plus battery systems to provide a comprehensive view of environmental impacts caused by the power supply.
Compatibility of structural materials with AlSi12 alloys-based phase change material and increasing the corrosion resistance by ceramic coatings
(Elsevier, 2023-11) Srinivasan, P.
Aluminum Silicon eutectic (AlSi12) alloy-based latent heat thermal energy storage can be integrated with concentrated solar power (CSP) to generate dispatchable power at an affordable cost. Despite AlSi12's favorable thermophysical properties, it reacts with steel at higher temperatures, posing a challenge for storage containers (structural materials). The use of ceramic materials as a protective coating for steel is possible due to their corrosion-resistant properties. Thus, this study examines the compatibility of steel structural materials (SS316, SS202, and P91) and ceramic-coated steel (Alumina – Al2O3 and Yttria Stabilized Zirconia – YSZ) with molten AlSi12. The experiment indicates that P91 steel and YSZ-coated steel have better corrosion resistance when measured over 120 h.
Computer aided design and manufacture of streamlined extrusion dies
(Elsevier, 2003-07) Srinivasan, P.
Extrusion is one of the widely used metal forming processes. The extrusion process is carried out conventionally using a shear faced die, but shear faced dies have many practical problems such as a dead metal zone, more redundant work, breaking of whiskers and above all the design of a shear die is done based on experience. To eliminate the above problems, a new approach of designing the die known as a streamlined die is tried here. The streamlined extrusion die is designed based on the principle of constant area reduction over the length of the die. In this, a uniform flow of metal is ensured from the surface to the core and this can be a more scientific approach of die design. Many methods are available in the literature to design the streamlined extrusion die such as cubic polynomial curves, the area mapping technique, the line-mapping technique and the use of a genetic algorithm. For solving the problem of die design Stokes’ theorem is suggested, but a new approach of transforming the peripheral point on the surface of a cylinder to the corresponding point on the extruded square is obtained by an analytical method. An attempt is made to identify an analytical solution for designing a streamlined extrusion die for a square cross-section.
Design and development of streamlined extrusion dies a Bezier curve approach
(Elsevier, 2005-04) Srinivasan, P.
Conventional shear dies used for extrusion of metals suffer from many problems. Attempts are made to improve the die design in many ways. Streamlined extrusion dies are considered to be better than shear dies. Streamlined extrusion dies are designed by various methods such as: (i) polynomial equation based dies (ii) area and line mapping technique (iii) analytical method. A new approach of designing streamlined dies using Bezier curve is attempted in this paper. Theoretical calculation on the total extrusion pressure for various friction factors is carried out. Comparison is made between Bezier curve based die and polynomial equation based dies. It is observed that the Bezier curve based die for the given takes lower extrusion pressure compared to other dies, for constant friction factor and area reduction.
Development of a Simulation Program to Optimise Process Parameters of Steam Power Cycles
(IASKS, 2014) Srinivasan, P.
Conventional coal-based thermal power plants have an average overall efficiency in the range of 35-38 %. Any increase in the percent efficiency of these power plants, is subjected to constraints posed by maximum and minimum temperatures, which are restricted by the creep property of materials and ambient temperature, respectively. Hence, an increase of efficiency beyond certain limits is not possible without optimising the process parameters associated with reheat and regenerative cycles. In this work, an attempt is made to optimise reheat and regenerative cycle process parameters such as, reheat pressure, tapping pressure of bled steam, and mass fraction of bled steam, in order to achieve maximum cycle efficiency. The optimisation of the process parameters was achieved by developing a simulation program using Microsoft Visual Studio. This program takes into account isentropic efficiencies of turbines and pumps and pressure drop in the boiler, and it can be used to simulate the optimum operating conditions of multi-stage reheat & regenerative cycle based thermal power plants. A comparison between the efficiencies of eight kinds of steam power cycles, at optimised conditions, has been made for different boiler pressures and steam temperatures at the turbine inlet. This comparison can aid power plant designers in choosing appropriate steam power cycles for a given set of operating conditions. It is observed that the results obtained from the program, such as, the optimum reheat pressures for two stage reheat cycles and optimum bled steam tapping pressures for two stage regenerative cycles are in good agreement with the published literature
Development of keyless biometric authenticated vehicles ignition system
(Elsevier, 2023) Srinivasan, P.
The vehicles are started or ignited using manual keys or sensor based keys. In two wheelers after placing keys the bike is started using either button or kicking method. The other vehicles are started using key cranking or key is placed in specific sensor control area and start button is pressed. The existing method makes any one can able to operate the vehicle if they have keys. The proposed method used to operate the vehicles only they are authorized. The authorization key is available in the controller memory. The proposed method uses dactylogram scanner to access the vehicles. The scanner scans the finger, if the person is authenticated immediately it allows the person to start the vehicles. The controller is attached with the relay electronic board which controls the ignition part. The proposed method uses ATMEGA 162. The device is able to access the vehicle by 3 persons. Only the specific 3 person finger prints are enrolled in the controller. The system is enabled with GSM access. If unauthenticated person access the finger print scanner, the vehicle is not ignited. The GSM module communicates the unauthenticated access attempt to the owner of the vehicles in the form of SMS. If the device is accessed with authenticated person and the vehicle is successfully started. In the meantime unauthorized person starts access with scanner, immediately message was received in the stored GSM mobile number. The average authentication time to start the vehicle is 3.81 s.
Development of three dimensional transient numerical heat conduction model with growth of oxide scale for steel billet reheat simulation
(Elsevier, 2014-10) Srinivasan, P.
This paper presents development of numerical heat conduction model for prediction of transient three dimensional temperature field in the billet. The model is applied to billet heating process in the reheat furnace. The discretization of governing equation is done by control volume approach and implicit scheme of finite difference method. The model captures various time dependent boundary conditions corresponding to the billet reheat in the reheat furnace, in addition to this it also accounts for the growth of oxide scale layer on the billet surfaces during reheat simulations. The set of discretized equations is solved using own developed MATLAB® code. The proposed model is capable of predicting the temperature field in the billet and scale growth on the billet surfaces. The model is validated with analytical results and published experimental results. The results obtained through the model simulations are in concurrence with the anticipated trend. The proposed methodology of numerical modeling will be helpful for the temperature and scale growth predictions, which are vital for a variety of reasons like energy efficiency, process optimization, roll force calculations, carbon segregation control and product microstructure control, etc.
Heat Transfer Simulation by CFD from Fins of an Air Cooled Motorcycle Engine under Varying Climatic Conditions
(World Congress on Engineering, 2011-07) Srinivasan, P.
An air-cooled motorcycle engine releases heat to the atmosphere through the mode of forced convection. To facilitate this, fins are provided on the outer surface of the cylinder. The heat transfer rate depends upon the velocity of the vehicle, fin geometry and the ambient temperature. Many experimental methods are available in literature to analyze the effect of these factors on the heat transfer rate. However, an attempt is made to simulate the heat transfer using CFD analysis. The heat transfer surface of the engine is modeled in GAMBIT and simulated in FLUENT software. An expression of average fin surface heat transfer coefficient in terms of wind velocity is obtained. It is observed that when the ambient temperature reduces to a very low value, it results in overcooling and poor efficiency of the engine
Implementation of battery degradation on lithiumion batteries using PYNQ-FPGA
(IEEE, 2024) Srinivasan, P.
Predicting the remaining usable life (RUL) of a lithium-ion battery properly is vital for appropriate maintenance and overall health evaluation, which is particularly pertinent in the burgeoning electric vehicle industry, where optimising battery performance is essential. Determining the rate of battery deterioration is a complex task because of the wide variety of internal and external elements that could affect it. Our study addresses this challenge by using datasets on battery ageing sourced from NASA's Prognostic Center of Excellence (PCoE) to introduce a data-driven approach for State of Health (SOH) estimation. In our pursuit of RUL prediction, we have devised a machine-learning model employing the ADAM optimiser for optimisation. Consequently, our proposed model utilises software programming on PYNQ FPGA to discern battery degradation. The findings of these innovative approaches are thoroughly analysed and assessed, showcasing the effectiveness of our approach in navigating the complexities associated with predicting battery RUL.
Internalizing the external cost of gaseous and particulate matter emissions from the coal-based thermal power plants in India
(Taylor & Francis, 2020-09) Srinivasan, P.
External cost or negative externality is a cost that a transaction or activity imposes on a party that is not part of the transaction or activity. In the present work, an attempt is made to calculate the external cost per unit of electricity generation from coal-based power plants in India due to the emissions of SO2, CO2, NOx and Particulate Matter. Purchasing Power Parity and population density correction factor are considered for the estimation of external cost to suit Indian economic and demographic conditions. Total external cost due to release of emissions from nine states having more coal-based power plants in India during the year 2018 is estimated to be INR 19.5 trillion and unit external cost of coal-based electricity generation is estimated to be INR 2.92. The cost of power generation from coal-based power plants in India with and without considering the external cost is estimated till the year 2030. Comparison is also made between the cost of solar power generation and coal-based thermal power generation. It is predicted that the cost of solar power generation without energy storage is cheaper than the power generation from coal-based power plants if the external cost of power generation is included in the cost.
Investigations on creep life of Alloy 617 material for the final stage superheater coils for ultra super critical thermal power plants
(Elsevier, 2020) Srinivasan, P.
Thermal power plant will continue to cater to the power demand of India at least for two more decades. Research is going on continuously to increase the temperature of operation of the materials used in power plant to increase the operating efficiency, conserve the fuel and reduce the environmental impact of power generation. Superheater coils made of nickel based alloys have an advantage over conventionally used materials like AISI 316, P91, P92 in powerplants. In the present work, an attempt is made to understand the creep related life of nickel based superalloy, Alloy 617 material in India powerplants. Alloy 617 can be a potential material for an ultra-super critical powerplant as it is known to withstand temperatures of around 700 °C and supercritical pressure upto 300 bar. These parameters significantly higher than the present operating values of 600 °C and 250 bar pressure in a typical Indian scenario. Extensive literature survey was carried out to understand the existing creep models, the thermophysical properties and parameters for evaluating Larson-Miller Parameter (LMP). Heat transfer simulation was carried out using ANSYS to predict the temperature field and the hoop stresses induced in the final stage of super heater coil exposed to the severest operating conditions in the power boiler, was predicted based on the boiler operating pressure in the ultra-super critical region. Formation and growth of oxide scale was not considered in the present model as literature suggests that the rate of oxide formation is negligible for the present material at 700 °C. Hoop stress and temperature distribution were used to predict the total life by applying Larson Miller Parameter approach. Robinson’s damage summation rule was attempted to determine the creep life of the material for the above conditions. Based on the analysis, it is observed that Alloy 617 can be the most suitable material for final stage superheater coil operating at around 700 °C.
IoT based air quality measurement and alert system for steel, material and copper processing industries
(Elsevier, 2023) Srinivasan, P.
The air quality of industry gets affected due to the industrial processing like heating of metals such as steel, copper. The burning and processing alters the level of NitrogenDioxide (NO2), Carbon Monoxide (CO), Carbon Dioxide (C02), methane (CH4), and Liquid Petroleum Gas (LPG). The each parameter in the air has to be maintained in safe level. If safe level is not maintained makes discomfort to the human health. The existing methods are measuring the air quality and display it at same station which may handle with less care. The proposed method consists of MQ2, MQ3, MQ6, and MQ9 sensors used to measure CO, CO2, NO2, and CH4 &LPG levels. The sensor gives the analog output. The proposed method uses the Arduino Nano - ATMEGA 168 based controlled to handle the analog sensors. The analog quantity is converted into digital value and which compared with safe limit value by the controller. The measured value is updated in cloud server- web based and Mobile application. The emergency alarm is fixed in the instrument in sound and light form to alert the workers. The device is tested in air polluted industry. The device showed the CO level as 525 PPM, NO2 level as 56 PBP, CO2 level as 164PPM, and mixed gas as 154PSI. The device notified CO level is high. The output is observed in cloud and mobile application.
Numerical and experimental investigation of melting process in spherical pcm capsule used for low-temperature thermal energy storage systems
(IOP, 2019) Srinivasan, P.
The present work deals with the experimental and numerical investigation of melting process of phase change material used for low temperature thermal energy storage applications. Thermal energy storage is a good solution to bridge the gap between energy supply and energy demand. The unconstrained melting of paraffin wax having melting range of 570C to 610C was studied in simple spherical glass capsule. The objective of the subject work is to perform the experimental and numerical analysis of melting process in spherical capsule subjected to constant wall temperature. Ansys Fluent 18 is used for computation purpose. In experimental analysis, melting process was observed through visual capturing of interface between solid and liquid. Melting fraction and temperature at the centre of PCM capsule are monitored both experimentally and numerically. Good consistency in results were observed.
Numerical simulation and experimental investigation on Phase Change Materials based energy storage system for cooling the water in process industries towards water conservation and environmental sustainability
(Elsevier, 2024-04) Srinivasan, P.
Water conservation is one of the significant concerns in the industrial sector in cooling processes. Water is lost predominantly in the cooling towers by evaporation, drift, and blowdown. A new Phase Change Material (PCM) based cooling system is proposed as a replacement for cooling towers to eliminate water losses completely. In the current research, the temperature drop of water known as range in the cooling tower is investigated in the proposed system by varying the process parameters such as water velocity, tube materials and tube lenght. In the present study, OM50, an organic PCM with a melting temperature of 500 C is chosen for experimental and numerical analysis as the normal operating temperature of water in the cooling towers is in this range. Based on the experiment, it is observed that the temperature range of water almost remains constant for the melt fraction values of PCM from about 0.1 to 0.8 and taking about 35 % of the total time required for completely melting the PCM. However the cooling range steeply decreases for the melt fraction variation from 0.8 to 1. Hence the designing of PCM based cooling system will be effective for the melting of the PCM from 0.1 to 0.8 leading to constant cooling range of temperature. The experimental results obtained are also validated by CFD simulation using ANSYS 18.1 and the results obtained are in close agreement with each other. The range obtained in the present research is almost in the same range of cooling tower used in the chiller plant presented in the case study. The proposed system may be able to replace cooling towers towards conservation of water and environmental sustainability.
Numerical simulations and experimental investigations to study the melting behavior of beeswax in a cylindrical container at different angular positions
(Elsevier, 2021-12) Srinivasan, P.
Phase Change Materials (PCMs) are widely used in Latent Heat Thermal Energy Storage Systems (LHTES). This work aims to study the melting behavior of low-temperature phase change materials in cylindrical containers placed at different angular positions. Simulations were performed using ANSYS FLUENT by applying the enthalpy porosity model to analyze melting of beeswax in a cylindrical glass tube subject to an isothermal wall condition. The tube was placed at angular positions of 0°, 30°, 60° and 90° to the horizontal in order to study the effect of angular position on melting behavior. The simulation results were then validated by performing experiments and capturing images at regular intervals of time to track the solid-liquid interface. Image processing using MATLAB was performed on the captured images to study the variation of melt fraction as a function of time. It is observed that the experimental results were in good agreement with the simulations. From these studies, it was observed that the total melting time increases with the angle of tilt from 0° to 90° Initially, the melting progressed similar to the analytical solutions of one-dimensional phase-change heat transfer. As the melting continued, the experimental and numerical results deviated from the analytical solutions and the rate of melting increased due to convection effects. The results obtained in this study can be used to predict the melting behavior of PCMs in a solar flat plate collector kept at different angular inclinations. This result can be kept in mind while designing a thermal energy storage system to set an appropriate angle to match the cycle time of the system.
Parametric analysis and optimization of a latent heat thermal energy storage system for concentrated solar power plants under realistic operating conditions
(Elsevier, 2021-08) Srinivasan, P.; Rai, Aakash Chand
High-temperature latent heat thermal energy storage (LHTES) systems are currently being considered for integration into concentrated solar power (CSP) plants; however, the challenge is to properly design the LHTES system under real-world operating conditions. Thus, this numerical investigation studied the effects of the LHTES system's design parameters on its performance under periodic steady-state with charging and discharging ‘cutoff’ temperatures to mimic its real-world operation. The study found that with the incorporation of cutoff temperatures, the system's specific energy and storage effectiveness decreased by 74% and 68%, respectively, due to lower useful charging and discharging times. Furthermore, the study demonstrated that the system's useful charging and discharging time could be augmented by increasing the shell radius (R) or length (L) of the system, or by decreasing the system's tube radius (ro) or the velocity of the heat transfer fluid (um) that flows through the system. The system's geometrical parameters (R, L, and ro) and um also substantially influenced its performance, but in a different manner than their influence on charging-discharging times. For example, increasing R deteriorated the system's performance substantially. Thus, we proposed optimized designs that achieved high charging-discharging times as well as good performance levels, using the response surface methodology.
Smart city air quality management with IOT and Bayesian optimization for pollution monitoring
(IEEE, 2025-02) Srinivasan, P.
The rapid urbanization happening around the globe is having a huge effect on the environment. Cities in the poor world are particularly vulnerable to air pollution. In light of this issue, several nations are mandating that cities implement plans to enhance air quality, and the new global air quality recommendations from the World Health Organization (WHO) are adding fuel to the fire. Inadequate outreach, few observations, disconnected city operations, and inconsistent protocols are some of the issues that hinder these deployments, as does the absence of collaborative UAQM governance. The proposed approach consists of three phases, which are data preparation, feature selection, and training. When it comes to categorical preprocessing, there are two typical ways to deal with missing values are after removing rows with missing values, use KNN Imputer to fill in the blanks. One goal of feature selection methods is to make analysis easier and faster by reducing the target dataset's dimensionality. Training the model was done using BO. With an average accuracy rate of 93.14 percent, the proposed model beats out the alternatives, including SVM and RBF.
Steel billet reheat simulation with growth of oxide layer and investigation on zone temperature sensitivity
(Springer, 2014-03) Srinivasan, P.
This paper presents a three-dimensional heat conduction numerical model and simulation of steel billet reheating in a reheat furnace. The model considers the growth of oxide scale on the billet surfaces. Control-volume approach and implicit scheme of finite difference method are used to discretize the transient heat conduction equation. The model is validated with analytical results subject to limited conditions. Simulations are carried out for predictions of three-dimensional temperature filed in the billet and oxide scale growth on the billet surfaces. The model predictions are in agreement with expected trends. It was found that the effect of oxide scale on billet heating is considerable. In order to investigate the effect of zone temperatures on the responses, a parametric sensitivity subject to six responses of interest are carried out using analysis of mean approach. The simulation approach and parametric study presented will be useful and applicable to the steel industry.