Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

In hydro power plants hydro turbine is a prime mover and is an important component. In case the hydro turbine does not function properly or is out of order for maintenance or otherwise, the plant suffers a huge loss of power generation and revenue. The function of the turbine also affects the efficiency, which may be reduced due to silt erosion/cavitation, which can be reduced to acceptable limits economically. The hydro turbine performance and its life were not improved significantly with various changes in design of turbine components by using distinct materials and the material coatings to the surface of the turbine blades. Therefore, it is essential to study the influence of abrasive erosion on the turbine components for various fluid flow conditions theoretically and experimentally. In present study, the silt erosion for different hydro turbines is estimated by using correlations available in the literature and compared the same. Cost analysis is carried out for the turbines affected due to erosion using cost of generation, cost of repair, maintenance cost and cost of mitigation which have been obtained from various turbine manufacturers. The analysis shall be helpful for the turbine manufacturers and plant owners for comparative analysis to decide whether to opt for preventive measures for silt erosion in turbines or for maintenance of turbines. It is observed from the analysis that the cost of coating is approximately 14 times and 130 times less than total loss of revenue for lower and higher concentrations respectively. © 2021 Author(s).

World University root node

Department of Thermal and Energy Engineering

School of Mechanical Engineering

Vellore Campus

AIP Conference Proceedings

Energy efficiency assessment in siltation affected hydroelectric dams

Electrical energy is an essential aspect of everyday human life through its different forms of application. However, due to limitation in resources and advancement of the civilization, energy demand could not be met appropriately complimenting the day-to-day population raise. Hence, it is imperative to depend renewable energy resources by adopting appropriate technologies. Thus, this study deals with energy generation to harness power from wind energy caused by high-speed locomotives using Savonius type of vertical axis wind turbine system. Installation of these systems along the path at a specific optimum range from the locomotive coach can provide energy generation. Computational studies were carried out using ANSYS in the wind speed range of 2.0–6.0 m/s. The wind turbine experimental setup was fabricated based on numerical results and experiments were conducted. Results reveal that a single high torque low speed turbine can generate 4–21 W. Potential power generation at identified sites in India was estimated, which can power low-capacity appliances at the vital railway stations. © 2021, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

Lecture Notes in Mechanical Engineering

Experimental Study on Vertical Axis Wind Turbine to Harness Wind Power from Rapidly Moving Railway Locomotives

This paper evaluates the exergy of an integrated two-stage humidification dehumidification (HDH) desalination with the cooling system. The exergy analysis was carried out for the experimental data generated from a laboratory level experimental setup. The experimental results were developed by varying hot water flow rate and its temperature to the humidifiers and air preheaters. The exergetic efficiency, exergy destruction of each component and desalinated water and gained out ratio (GOR) of the system are evaluated for different experimental conditions. The system performance was evaluated with hot water is supplied at 100,125,150,200 L per hour to humidifiers at different inlet temperatures. Atmospheric air is supplied at a flow rate of 15 cubic metre per hour and maintained it constant throughout the experiments. The desalination yield increases with an increase in water flow rate and its temperature, whereas the cooling effect is observed a decreasing trend. The exergy efficiency in air preheaters, humidifiers and dehumidifiers was observed to be 20–30%, 70–90%, and 30–60%, respectively. Total desalinated water yield of 1.2–1.9 kg per hour is obtained with a GOR of 0.7–1.6 is from the integrated system. Air cooling of 0.1–0.25 kW is observed from the system for the mentioned flow rate of air and hot saline water. © 2021, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

Exergy Studies on a Hybrid Desalination and Cooling Plant

Desalination by humidification dehumidification processes is a promising simple, cost effective and low maintenance concept. It works on the principle of air humidification at high temperature and dehumidification at relatively low temperatures. The present study is for evaluating the performance of the humidifier with coconut coir as packing material used for air humidification in the solar humidification dehumidification (HDH) desalination plant. Experiments were carried out on the humidifier packing for different flow rates of water and its temperature. Humidifier range, effectiveness and efficiency, evaporation rate of water, heat and mass transfer rates are studied by experimentally for different flow rates of hot water and its temperature. The hot water flow rate is varied from 125 to 225 LPH with an increment of 25 LPH and water temperature from 38 to 54°C. It is found that at water flow rate of 200 LPH and at 0.55 m3/s volume flow rate of air, effectiveness of humidifier found to be maximum of 0.74. Copyright © 2019 Inderscience Enterprises Ltd.

VIT Unitversity

Progress in Industrial Ecology, An International Journal

Experimental investigation on a coconut coir packed humidifier for a solar desalination plant

Rapid growth in urbanization, industrialization and decrease in rainfall rates all over the world demands more fresh water for human use, industries and agriculture purpose. The novel desalination technologies for converting saline water into fresh water have more value and demand. Present work aim at evaluating the performance of an integrated air cooling and two stage desalination system using humidification dehumidification (HDH) technology experimentally by varying flow rate and temperature of saline water. The components of the proposed system are designed, developed and carried out experiments for different operating conditions to get optimum operating conditions. The plant consists of a solar water heater (SWH), two air preheaters, two humidifiers, two dehumidifiers with a normal and a vapour compression refrigeration water chiller. The influence of saline water temperature and flow rate on air temperature, desalination yield, recovery ratio, energy utilization factor (EUF), air cooling effect and coefficient of performance (COP) of the cooling system are studied. The experimental observations recommend higher saline water temperature with high flow rates to air preheaters and humidifiers, circulating and chilled water to dehumidifiers with lower possible temperatures. The integrated plant yields 240 W of cooling energy and a maximum fresh water of 2180 ml/h with 15 m3/h air flow at saline water temperature of 54.5°C with a flow rate of 200 LPH. Experimental results show a maximum EUF of 0.5 for the hybrid plant and 0.45 for conventional plant single stage plant. A maximum COP of 2.2 with a recovery ratio of 0.78 is observed from the experimental results. © 2019 Desalination Publications. All rights reserved.

Department of Smart Computing

School of Information Technology and Engineering

DESALINATION AND WATER TREATMENT

Experimental investigation on a hybrid desalination and cooling unit using humidification-dehumidification technique

Humidification–dehumidification (HDH) desalination is a simple technique to produce desalinated water from saline water. Dehumidifier is a key component in the HDH system, which influences the desalination yield. In the current work, a three-dimensional multiphase numerical simulation study is carried out on third dehumidifier alone to evaluate its performance using computational fluid dynamics (CFD) code. The simulation result is validated with experimental readings, and it is found that there exists a very close agreement between the predicted and the experimental readings. The key parameters influencing the dehumidifier performance are chilled water temperature, humid air temperature, and volume fraction. Experiments are carried out on the combined two stage HDH plant at different hot water temperature and flow rates. A detailed study of dehumidification process is carried out using ansys cfx 15.0 tool by solving the governing equations, namely, mass, momentum, and energy, with turbulence modeled through shear stress transport (SST) k–ω model of closure. Multiphase is solved using a free-surface multiphase model. The measured average cooled air temperature and relative humidity (RH) at the exit of third dehumidifier are 21 °C and 67%. The desalinated water produced at a hot water flow of 100 LPH is found as 2205 ml/h from the experiments. The CFD results are deviated by 0.41%, 6.45%, and −0.70% with that of experimental results at the dehumidifier for air temperature, velocity, and chilled water temperature, respectively.

Department of Automotive Engineering

Journal of Thermal Science and Engineering Applications

Experimental and Computational Fluid Dynamics Studies on Dehumidifier in a Combined Cooling and Desalination Plant

Humidifier is an important component in air humidification-dehumidification desalination plant for fresh water production. Liquid to air flow rate ratio is optimization is reported for an industrial cooling towers but for an air humidifier it is not addressed. The current work is focused on the design and analysis of an air humidifier for solar desalination plant to maximize the yield with better humidification, using finite difference method (FDM). The outlet conditions of air from the humidifier are theoretically predicted by FDM with the given inlet conditions, which will be further used in the design calculation of the humidifier. Hot water to air flow rate ratio and inlet hot water temperature are identified as key operating parameters to evaluate the humidifier performance. The maximum and optimal values of mass flow rate ratio of water to air are found to be 2.15 and 1.5 respectively using packing function and Merkel Integral. The height of humidifier is constrained to 1.5 m and the diameter of the humidifier is found as 0.28m. The performance of humidifier and outlet conditions of air are simulated using FDM and compared with experimental results. The obtained results are within an agreeable range of deviation. © 2017 Published under licence by IOP Publishing Ltd.

Fulltext

IOP Conference Series: Materials Science and Engineering

Design and development of an air humidifier using finite difference method for a solar desalination plant

Humidification–dehumidification (HDH) desalination works based on a water cycle principle and involves air humidification and condensation (dehumidification). The cooling of humid air with chilled water increases the desalination and results in cold air suitable for air conditioning process. The merits of the proposed HDH desalination and cooling are not analyzed and compared in the literature. Therefore, the performance results of HDH with normal water (current technology) and HDH with chilled water (proposed idea) are compared to highlight the merit of this cycle. The combined cycle for desalination and cooling has been solved thermodynamically with psychrometric properties. The results are validated with a laboratory experimental setup. The examined operational process conditions are hot water inlet temperature, efficiency of humidifier, and vapor absorption refrigerator's (VAR's) evaporator exit temperature. The focused results are desalination, cooling and energy utilization factor (EUF). The comparative study recommends the use of chilled water in the final stage. The two stage desalination with dehumidification by normal water in the first stage and chilled water in combined two stages improves the cycle EUF from 0.18 to 0.33. Out of 300 W of cooling generation, 100 W is used for dehumidification and the remaining 200 W is available for air conditioning process at 15 N⋅m3 h−1 of air. © 2017 Elsevier Ltd and IIR

International Journal of Refrigeration

Augmented desalination with cooling integration

This work evaluates a two-stage humidification-dehumidification (HDH) process for combined air cooling and desalination for fresh water production from salt water experimentally. A pilot scale plant is designed and constructed with 16 m2 solar collector area for salt water heating. The operational parameters identified are hot saline water supply to humidifiers and it's temperature. The saline water is heated in a solar water heater (SWH) and supplied to the two humidifiers and air preheaters. Main performance parameters i.e. desalinated water generation, cooling effect and energy utilization factor (EUF) of the plant is studied in the light of hot water inlet temperature and its flow rate. It is observed that a maximum of 2.5 LPH of fresh water is produced at a water and air flow rates of 300 LPH and 10 m3/hr respectively. At low inlet water temperatures the resulted cooling effect is more compared with high temperatures and an average of 120 W of cooling effect is produced. The energy utilization factor (EUF) of combined two stage desalination and cooling plant is more compared with individual single stage plants and an average value of 0.4 is attained for combined plant. On overall basis, maximum possible water flow rate in humidifier and also high temperatures are recommended to yield more desalination output. © 2016 The Authors.

Energy Procedia

Experimental Analysis of Augmented Desalination by Cooling Integration

The desalination yield in humidification-dehumidification (HDH) process is increased by proposing cooling plant integration with two stage operation. The current work is targeted on the investigation of vapor absorption refrigeration (VAR) parameters on overall energy utilization factor (EUF). The dephlegmator heat is recovered internally in VAR instead of rejecting to environment. This work can be used to control the operational conditions of VAR to enhance the desalination and cooling together. The studied process parameters in VAR are strong solution concentration, separator or generator temperature, dephlegmator effectiveness, circulating water inlet temperature and evaporator temperature. Out of these five variables, lower limit of separator temperature, upper limit of dephlegmator effectiveness and lower limit of circulating water temperature are fixed in the specified range to attain the optimum strong solution concentration and optimum evaporator temperature. At the specified boundaries of three variables, the optimized strong solution concentration and evaporator temperature are 0.47 and 10 °C respectively. At this condition, the maximized cycle EUF is 0.358. © 2016 Faculty of Engineering, Alexandria University

Alexandria Engineering Journal

Influence of vapor absorption cooling on humidification-dehumidification (HDH) desalination

Humidification-dehumidification (HDH) desalination is a simple and cost effective solution to convert the saline water into desalinated water. In current work, desalination yield has been augmented with two stage HDH integrated cooling plant. A pilot plant has been developed and analyzed with experimental and simulation studies. The identified operational variants are hot saline water supply to humidifiers and its inlet temperature. The saline water is heated in a solar water heater (SWH) and supplied to two humidifiers and two air preheaters. The simulated results developed for subsystems are validated with the experimental readings. Desalination yield is not satisfactory level at lower water temperature in the first stage plant but there is no such limitation in the second stage operation. Nearly 1.5 LPH of desalinated water is resulted at 15m3/h of air. The energy utilization factor (EUF) of two stage plant is concentrated at higher side compared to the single stage plant's EUF. The increased flow of saline water in humidifiers and its high temperature is favoring the desalination output but with a penalty in cooling effect. © 2015 Elsevier B.V.

Desalination

Experimental and simulation studies on two stage humidification–dehumidification desalination and cooling plant

Two or more than two outputs from a single source result an overall high energy utilization factor (EUF) compared to the single output system. In this work, two stage humidification and dehumidification (HDH) desalination system has been extended with cooling system integration. Solar flat plate collector and concentrating collector are selected respectively for HDH desalination and single effect vapor absorption refrigeration (VAR) plant. The cooling after desalination increases the yield of distillation compared to without its integration. The sequence of operations in the combined plant is first stage air preheatinghumidification-dehumidification, second stage air preheating-humidification-dehumidification and final cooling of air with chilled water. The work is aimed on thermodynamic study for maximization of EUF for cycle and plant. The role of humidifier efficiency, its effectiveness, hot water temperature and chilled water temperature (by varying VAR evaporator temperature) has been studied on integrated performance. The resulted distilled water is 670 LPH with 75kW cooling at unit volume of air (1m3/s). The cycle EUF and plant EUF are 0.58 and 0.33 respectively. © 2014 Elsevier B.V.

Combined two stage desalination and cooling plant

Solar thermal energy is currently used for low temperature heating applications using flat plate collectors. The absorbed solar energy is transferred to the working fluid flowing in the pipe. The performance of the system is influenced by heat transfer from tube to working fluid, with minimum convective losses, which has to be considered as one of the primary design factor. In tube and channel flows, to enhance the rate of heat transfer to the working fluid, passive augmentation techniques such as twisted tapes and swirl generators are used in the fluid flow path. In this paper, convective heat transfer analysis for a horizontal circular pipe with fluid in mixed laminar flow range is performed using experimental simulation under constant heat flux boundary condition. The variation of heat transfer coefficient and pressure drop in the pipe flow for water and water based Al2O3 nanofluids at different volume concentrations and twisted tapes are studied. The dependence of particle concentration and Reynolds number for enhancement in heat transfer and increase in the pumping power due to pressure drop is analysed in the range of parameters considered. © 2013 The Authors. Published by Elsevier Ltd.