DOCSLIB.ORG

Laboratory and Modelling Study Evaluating Thermal Remediation of Tetrachloroethene and Multi- Component Napl Impacted Soil

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Laboratory and Modelling Study Evaluating Thermal Remediation of Tetrachloroethene and Multi- Component Napl Impacted Soil LABORATORY AND MODELLING STUDY EVALUATING THERMAL REMEDIATION OF TETRACHLOROETHENE AND MULTI- COMPONENT NAPL IMPACTED SOIL by Chen Zhao A thesis submitted to the Department of Civil Engineering In conformity with the requirements for Master of Applied Science Queen’s University Kingston, Ontario, Canada (September 2013) Copyright © Chen Zhao, 2013 Abstract Dense non-aqueous phase liquids (DNAPLs) such as chlorinated solvents, coal tar and creosote are some of the most problematic groundwater and soil contaminants in industrialized countries throughout the world. In Situ Thermal Treatment (ISTT) is a candidate remediation technology for this class of contaminants. However, the relationships between gas production, gas flow, and contaminant mass removal during ISTT are not fully understood. A laboratory study was conducted to assess the degree of mass removal, as well as the gas generation rate and the composition of the gas phase as a function of different heating times and initial DNAPL saturations. Experiments consisted of a soil, water, and DNAPL mixture packed in a 1 L jar that was heated in an oven. Gas produced during each experiment, which consisted of steam and volatile organic compounds (VOCs), was collected and condensed to quantify the gas generation rate. The temperature of the contaminated soil was measured continuously using a thermocouple embedded in the source zone, and was used to identify periods of heating, co-boiling and boiling. Samples were collected from the aqueous and DNAPL phase of the condensate, as well as from the source soil, at different heating times, and analyzed by gas chromatography/mass spectrometry. In addition to laboratory experiments, a mathematical model was developed to predict the co-boiling temperature and transient composition of the gas phase during heating of a uniform source. Predictions for single-component sources matched the experiments well, with a co-boiling plateau at 88°C ± 1°C for experiments with tetrachloroethene (PCE) and water. A comparison of predicted and observed boiling behaviour showed a discrepancy at the end of the co- boiling period, with earlier temperature increases occurring in the experiments. The results of this study suggest that temperature observations related to the co-boiling period during ISTT ii applications may not provide a clear indication of complete NAPL mass removal, and that multi-compartment modeling associated with various NAPL saturation zones is required to consider mass-transfer limitations within the heated zone. Predictions for multi-component DNAPL, containing 1,2-Dichloroethane (1,2-DCA), PCE and Chlorobenzene, showed no co- boiling plateau. 1,2-DCA, the most volatile component, was found to be removed from soil by heating fastest during co-boiling. CB is the least volatile component and dominates in the vapour phase at the end of the co-boiling process, and it can be used as an indicator of the end of the co-boiling stage. Two field NAPL mixtures were simulated using the screening-level analytical model to demonstrate its potential application on ISTT. The two mixtures, which have similar composition but different mass fractions result in distinct co-boiling temperature and mass transfer behaviour. The non-volatile component in the NAPL mixture results in larger amounts of water consumption and longer ISTT operation time. iii Acknowledgements This research project was supported by student scholarships from Queen’s University and the Natural Sciences and Engineering Research Council (NSERC) of Canada through a Strategic Project Grant. I would like to express my appreciation to my supervisors Dr. Kevin Mumford and Dr. Bernie Kueper. You provided me the opportunity to work on this project, which makes my knowledge and experience extended. Your guidance, advice and encouragement have helped me a lot to complete my thesis research. Grateful thanks to the technical support provided by Stan Prunster and Neil Porter. The assistance of Dr. Allison Rutter and with Paula Whitley at the Queen’s University Analytical Services Unit was essential for development of the analytical method. Many thanks to the members of the groundwater research group, especially Eric Martin, Paul Hegele, Sean Bryck and Owen Miles for their support and help. I also would like to express my appreciation to my parents for their endless love, support and encouragement. iv Forward This thesis has been written in a manuscript format. Chapter 1 gives a general introduction, and Chapter 2 provides a review of relevant literature. Chapters 3 and 4 are independent manuscripts that will be submitted for publication. I will be the first author on both of these publications; Drs. Mumford and Kueper will be coauthors. Chapter 5 summarizes the experimental and modeling results of this study, and also gives recommendations of future study. Supplemental experimental data and calculations, information on the analytical method and analytical error, details regarding the mathematical model, information on the properties of 1,2-dichoroethane, tetrachloroethene and chlorobenzene as a function of temperature, and the soil moisture measurements by time domain reflectometry (TDR) are provided in Appendices A through E. v Table of Contents Abstract ........................................................................................................................................... ii Acknowledgements ........................................................................................................................ iv Forward ............................................................................................................................................v List of Figures ................................................................................................................................ ix List of Tables ................................................................................................................................. xi Nomenclature ................................................................................................................................ xii Abbreviations ............................................................................................................................... xvi Chapter 1 Introduction ......................................................................................................................................1 1.1 DNAPL and Chlorinated Solvents ..........................................................................................1 1.2 Thermal Remediation ..............................................................................................................3 1.3 Research Objectives ................................................................................................................4 1.4 Thesis Overview .....................................................................................................................5 1.5 Literature Cited .......................................................................................................................7 Chapter 2 Literature Review .............................................................................................................................8 2.1 Heat Transfer Mechanisms .....................................................................................................8 2.1.1 Conduction Overview .................................................................................................8 2.1.2 Conduction in Porous Media ....................................................................................10 2.1.3 Convection Overview ...............................................................................................12 2.1.4 Convection in Porous Media ....................................................................................13 2.1.5 Thermal Properties of Soil ........................................................................................13 2.2 Phase Change ........................................................................................................................14 2.2.1 Boiling of Pure Liquids ............................................................................................14 2.2.2 Boiling of Miscible Mixtures ...................................................................................17 2.2.3 Boiling of Immiscible Mixtures ...............................................................................18 2.3 Effects of Temperature on Physicochemical Properties .......................................................22 2.3.1 Water-Gas Partitioning (Henry’s Law) ....................................................................22 2.3.2 DNAPL-Water Partitioning (Solubility) ..................................................................23 2.3.3 Adsorption ................................................................................................................24 vi 2.3.4 Total VOC Concentration .........................................................................................25 2.4 ISTT Technologies ................................................................................................................26 2.4.1 Electrical Resistance Heating ...................................................................................26 2.4.2 Thermal Conductive Heating ...................................................................................28 2.4.3 Importance of Vapour Extraction .............................................................................29
Load more

Recommended publications
  • Problem Formulation of the Risk Evaluation for Perchloroethylene (Ethene, 1,1,2,2-Tetrachloro)
    EPA Document# EPA-740-R1-7017 May 2018 DRAFTUnited States Office of Chemical Safety and Environmental Protection Agency Pollution Prevention Problem Formulation of the Risk Evaluation for Perchloroethylene (Ethene, 1,1,2,2-Tetrachloro) CASRN: 127-18-4 May 2018 TABLE OF CONTENTS ABBREVIATIONS ............................................................................................................................ 8 EXECUTIVE SUMMARY .............................................................................................................. 11 1 INTRODUCTION .................................................................................................................... 14 1.1 Regulatory History ..................................................................................................................... 16 1.2 Assessment History .................................................................................................................... 16 1.3 Data and Information Collection ................................................................................................ 18 1.4 Data Screening During Problem Formulation ............................................................................ 19 2 PROBLEM FORMULATION ................................................................................................. 20 2.1 Physical and Chemical Properties .............................................................................................. 20 2.2 Conditions of Use ......................................................................................................................
    [Show full text]
  • Toxicological Profile for Tetrachloroethylene
    TETRACHLOROETHYLENE 263 6. POTENTIAL FOR HUMAN EXPOSURE 6.1 OVERVIEW Tetrachloroethylene has been identified in at least 949 of the 1,854 hazardous waste sites that have been proposed for inclusion on the EPA National Priorities List (NPL) (ATSDR 2017a). However, the number of sites evaluated for tetrachloroethylene is not known. The frequency of these sites can be seen in Figure 6-1. Of these sites, 943 are located within the United States, 3 are located in the Commonwealth of Puerto Rico (not shown), 1 is located in Guam (not shown), and 1 is located in the Virgin Islands (not shown). Tetrachloroethylene is a VOC that is widely distributed in the environment. It is released to the environment via industrial emissions and from building and consumer products. Releases are primarily to the atmosphere. However, the compound is also released to surface water and land in sewage sludges and in other liquid and solid waste, where its high vapor pressure and Henry's law constant usually result in its rapid volatilization to the atmosphere. Tetrachloroethylene has relatively low solubility in water and has medium-to-high mobility in soil; thus, its residence time in surface environments is not expected to be more than a few days. However, it persists in the atmosphere for several months and can last for decades in the groundwater. Background tetrachloroethylene levels in outdoor air are typically <1 μg/m3 (0.15 ppb) for most locations (EPA 2013h, 2018); however, indoor air at source dominant facilities (e.g., dry cleaners) has been shown to have levels >1 mg/m3 (Chiappini et al.
    [Show full text]
  • Vapour Absorption Refrigeration Systems
    Lesson 14 Vapour Absorption Refrigeration Systems Version 1 ME, IIT Kharagpur 1 The objectives of this lesson are to: 1. Introduce vapour absorption refrigeration systems (Section 14.1) 2. Explain the basic principle of a vapour absorption refrigeration system (Section 14.2) 3. Compare vapour compression refrigeration systems with continuous vapour absorption refrigeration systems (Section 14.2) 4. Obtain expression for maximum COP of ideal absorption refrigeration system (Section 14.3) 5. Discuss properties of ideal and real refrigerant-absorbent mixtures (Section 14.4) 6. Describe a single stage vapour absorption refrigeration system with solution heat exchanger (Section 14.5) 7. Discuss the desirable properties of refrigerant-absorbent pairs for vapour absorption refrigeration systems and list the commonly used working fluids (Section 14.6) At the end of the lecture, the student should be able to: 1. List salient features of vapour absorption refrigeration systems and compare them with vapour compression refrigeration systems 2. Explain the basic principle of absorption refrigeration systems and describe intermittent and continuous vapour absorption refrigeration systems 3. Find the maximum possible COP of vapour absorption refrigeration systems 4. Explain the differences between ideal and real mixtures using pressure- composition and enthalpy-composition diagrams 5. Draw the schematic of a complete, single stage vapour absorption refrigeration system and explain the function of solution heat exchanger 6. List the desirable properties of working fluids for absorption refrigeration systems and list some commonly used fluid pairs 14.1. Introduction Vapour Absorption Refrigeration Systems (VARS) belong to the class of vapour cycles similar to vapour compression refrigeration systems. However, unlike vapour compression refrigeration systems, the required input to absorption systems is in the form of heat.
    [Show full text]
  • A Simple Theoretical Model of Heat and Moisture Transport in Multi-Layer Garments in Cool Ambient Air
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Loughborough University Institutional Repository This item was submitted to Loughborough’s Institutional Repository (https://dspace.lboro.ac.uk/) by the author and is made available under the following Creative Commons Licence conditions. For the full text of this licence, please go to: http://creativecommons.org/licenses/by-nc-nd/2.5/ A Simple Theoretical Model of Heat and Moisture Transport in Multi-layer Garments in Cool Ambient Air Eugene H. Wissler Department of Chemical Engineering The University of Texas at Austin Austin, Texas, USA George Havenith Environmental Ergonomics Research Group Department of human sciences Loughborough University Loughborough LE11 3TU, UK Tel. No.: (936) 597-9233 e-mail: [email protected] Abstract Overall resistances for heat and vapour transport in a multilayer garment depend on the properties of individual layers and the thickness of any air space between layers. Under uncomplicated, steady-state conditions, thermal and mass fluxes are uniform within the garment, and the rate of transport is simply computed as the overall temperature or water concentration difference divided by the appropriate resistance. However, that simple computation is not valid under cool ambient conditions when the vapour permeability of the garment is low, and condensation occurs within the garment. Several recent studies have measured heat and vapour transport when condensation occurs within the garment (Richards, et al., 2002, and Havenith, et al., 2008). In addition to measuring cooling rates for ensembles when the skin was either wet or dry, both studies employed a flat-plate apparatus to measure resistances of individual layers.
    [Show full text]
  • 1,2-DICHLOROETHANE 1. Exposure Data
    1,2-DICHLOROETHANE Data were last reviewed in IARC (1979) and the compound was classified in IARC Monographs Supplement 7 (1987a). 1. Exposure Data 1.1 Chemical and physical data 1.1.1 Nomenclature Chem. Abstr. Serv. Reg. No.: 107-06-2 Chem. Abstr. Name: 1,2-Dichloroethane IUPAC Systematic Name: 1,2-Dichloroethane Synonym: Ethylene dichloride 1.1.2 Structural and molecular formulae and relative molecular mass Cl CH2 CH2 Cl C2H4Cl2 Relative molecular mass: 98.96 1.1.3 Chemical and physical properties of the pure substance (a) Description: Colourless liquid with a pleasant odour (Budavari, 1996) (b) Boiling-point: 83.5°C (Lide, 1995) (c) Melting-point: –35.5°C (Lide, 1995) (d) Solubility: Slightly soluble in water; miscible with ethanol, chloroform and diethyl ether (Lide, 1995; Budavari, 1996) (e) Vapour pressure: 8 kPa at 20°C (Verschueren, 1996) (f) Flash-point: 18°C, open cup (Budavari, 1996) (g) Conversion factor: mg/m3 = 4.0 × ppm 1.2 Production and use World production capacities in 1988 for 1,2-dichloroethane have been reported as follows (thousand tonnes): North America, 9445; western Europe, 9830; Japan, 3068; and other, 8351 (Snedecor, 1993). Production in the United States has been reported as follows (thousand tonnes): 1983, 5200; 1990, 6300; 1991, 6200; 1992, 6900; 1993, 8100 (United States National Library of Medicine, 1997). The total annual production in Canada in 1990 was estimated to be 922 thousand tonnes; more than 1000 thousand tonnes were produced in the United Kingdom in 1991 (WHO, 1995). –501– 502 IARC MONOGRAPHS VOLUME 71 1,2-Dichloroethane is used primarily in the production of vinyl chloride; 99% of total demand in Canada, 90% in Japan and 88% of total production in the United States are used for this purpose.
    [Show full text]
  • Evaluating the Vapour Evaporation from the Surface of Liquid Pure Organic Solvents and Their Mixtures
    Food Science and Applied Biotechnology, 2020, 3(1), 77-84 Food Science and Applied Biotechnology Journal home page: www.ijfsab.com https://doi.org/10.30721/fsab2020.v3.i1 Research Article Evaluating the vapour evaporation from the surface of liquid pure organic solvents and their mixtures Stepan Akterian1✉ 1 Department of Technology of fats, essential oils, perfumery and cosmetics. Technological Faculty. University of Food Technologies - Plovdiv. Bulgaria Abstract Some perfumery and cosmetic products represent mixtures and they include large parts of solvents as ethanol, water, acetone and isopropyl alcohol. Solvents as pure hexane and ethanol-water mixtures are used in the solvent extraction of oil-bearing plant materials and herbs. The goal of this study was the emissions of volatile solvents released during above pointed productions to be evaluated. It was found that the specific evaporation rate varies from 1.2 kg/(m2.h) (for pure methoxy-propanol) to 66 kg/(m2.h) (for three-component mixture including acetone). The evaporation rate is higher for solvents with higher vapour pressure and at a higher velocity of surrounding air. The evaporation is less intensive from pure solvents than their mixtures. The time for the evaporation from a film of solvents and their mix- tures was also evaluated. It varies from 14 s (for acetone) to 9 min (for methoxy-propanol). Practical applications: The evaluation of volatile solvent emissions is a mandatory step in the design of plants for manufacturing perfumery, cosmetics, deriving essential and edible oils by means of organic solvents. Most of volatile organic solvents used are highly flammable and healthy hazardous.
    [Show full text]
  • Unit 5 Psychometric 2. Explain the Properties of Phychrometry
    Unit 5 Psychometric 1. What is psychometry. Atmospheric air makes up the environment in almost every type of air conditioning system. Hence a thorough understanding of the properties of atmospheric air and the ability to analyze various processes involving air is fundamental to air conditioning design. Psychrometry is the study of the properties of mixtures of air and water vapour. Atmospheric air is a mixture of many gases plus water vapour and a number of pollutants (Fig.27.1). The amount of water vapour and pollutants vary from place to place. The concentration of water vapour and pollutants decrease with altitude, and above an altitude of about 10 km, atmospheric air consists of only dry air. The pollutants have to be filtered out before processing the air. Hence, what we process is essentially a mixture of various gases that constitute air and water vapour. This mixture is known as moist air. The moist air can be thought of as a mixture of dry air and moisture. 2. Explain the Properties of Phychrometry The properties of moist air are called psychrometric properties and the subject which deals with the behaviour of moist air is known as psychrometry. Moist air is a mixture of dry air and water vapour. They form a binary mixture. A mixture of two substances requires three properties to completely define its thermodynamic state, unlike a pure substance which requires only two. One of the three properties can be the composition. Water vapour is present in the atmosphere at a very low partial pressure. At this low pressure and atmospheric temperature, the water vapour behaves as a perfect gas.
    [Show full text]
  • Tetrachloroethylene Facts
    TETRACHLOROETHYLENE CAS # 127-18-4 Agency for Toxic Substances and Disease Registry ToxFAQs September 1997 This fact sheet answers the most frequently asked health questions (FAQs) about tetrachloroethylene. For more information, call the ATSDR Information Center at 1-888-422-8737. This fact sheet is one in a series of summaries about hazardous substances and their health effects. It’s important you understand this information because this substance may harm you. The effects of exposure to any hazardous substance depend on the dose, the duration, how you are exposed, personal traits and habits, and whether other chemicals are present. HIGHLIGHTS: Tetrachloroethylene is a manufactured chemical used for dry cleaning and metal degreasing. Exposure to very high concentrations of tetrachloroethylene can cause dizziness, headaches, sleepiness, confusion, nausea, difficulty in speaking and walking, unconsciousness, and death. Tetrachloroethylene has been found in at least 771 of the 1,430 National Priorities List sites identified by the Environmental Protection Agency (EPA). What is tetrachloroethylene? How might I be exposed to tetrachloroethylene? (Pronounced tµt”r…-klôr“ ½-µth“…-l¶n”) q When you bring clothes from the dry cleaners, they will release small amounts of tetrachloroethylene into the air. Tetrachloroethylene is a manufactured chemical that is q widely used for dry cleaning of fabrics and for metal-degreas- When you drink water containing tetrachloroethylene, you are exposed to it. ing. It is also used to make other chemicals and is used in some consumer products. Other names for tetrachloroethylene include perchloroet- How can tetrachloroethylene affect my health? hylene, PCE, and tetrachloroethene. It is a nonflammable High concentrations of tetrachloroethylene (particularly liquid at room temperature.
    [Show full text]
  • Psychrometry Psychrometric Properties Atmospheric Air Makes up the Environment in Almost Every Type of Air Conditioning System
    Psychrometry Psychrometric Properties Atmospheric air makes up the environment in almost every type of air conditioning system. Hence a thorough understanding of the properties of atmospheric air and the ability to analyze various processes involving air is fundamental to air conditioning design. Psychrometry is the study of the properties of mixtures of air and water vapour. Atmospheric air is a mixture of many gases plus water vapour and a number of pollutants. The amount of water vapour and pollutants vary from place to place. The concentration of water vapour and pollutants decrease with altitude, and above an altitude of about 10 km, atmospheric air consists of only dry air. The pollutants have to be filtered out before processing the air. Hence, what we process is essentially a mixture of various gases that constitute air and water vapour. This mixture is known as moist air. Fig. Atmospheric air The molecular weight of dry air is found to be 28.966 and the gas constant R is 287.035 J/kgK. The molecular weight of water vapour is taken as 18.015 and its gas constant R is 461.52 J/kgK. 1 Specific Humidity or Humidity Ratio The humidity ratio (or specific humidity) W is the mass of water associated with each kilogram of dry air. Assuming both water vapour and dry air to be perfect gases, the humidity ratio is given by: Substituting the values of gas constants of water vapour and air Rv and Ra in the above equation; the humidity ratio is given by: Specific humidity or absolute humidity or humidity ratio (w) = If Pa and Pv denote respectively the partial pressure of dry air and that of water vapour in moist air, the specific humidity of air is given by (We know Pa = Pb – Pv) 2 Where ф is the relative humidity (in fraction).
    [Show full text]
  • Chapter 6 (Pdf)
    6. Fanefjord Church and Gundsømagle Church 109 6 CASE STUDIES IN HUMIDITY BUFFERING BY POROUS WALLS Humidity buffering in the real world The purpose of the experimental part of this thesis has been to give some quantitative support to the concept of using interior walls as buffers for the interior climate, particularly in museums and archives. In this chapter I describe some case histories where the principle of using porous materials as a buffer has been applied in real life. In some of these examples buffering has not been the intent of the builder. Humidity buffering by the walls of Fanefjord Church There are few buildings which are porous right through. Stables and churches are just about the only buildings which have a porous inner surface to the outer walls. They are limewashed and many of the churches are also decorated with ancient paintings. It is the challenge of preserving these paintings that has provided the opportunity to study their microclimate in some detail. The first example is Fanefjord Church on the Danish island of Møn (23). The walls are made of brick, with lime plaster inside Figure 6.1 Fanefjord Church, Møn, and outside. The ceiling is brick vaults. Denmark, from the south west. The climate inside and outside the church is Photo: Poul Klenz Larsen shown in figure 6.2. The inside RH is lower than that outside, as expected, because the church is heated. The diagram also has a line showing the expected inside RH, calculated from the water content of the outside air, operated on by the inside temperature The observed RH is higher than it should be and is remarkably stable at about 45%.
    [Show full text]
  • Revisiting Kelvin Equation and Peng–Robinson Equation of State For
    www.nature.com/scientificreports OPEN Revisiting Kelvin equation and Peng–Robinson equation of state for accurate modeling of hydrocarbon phase behavior in nano capillaries Ilyas Al‑Kindi & Tayfun Babadagli* The thermodynamics of fuids in confned (capillary) media is diferent from the bulk conditions due to the efects of the surface tension, wettability, and pore radius as described by the classical Kelvin equation. This study provides experimental data showing the deviation of propane vapour pressures in capillary media from the bulk conditions. Comparisons were also made with the vapour pressures calculated by the Peng–Robinson equation‑of‑state (PR‑EOS). While the propane vapour pressures measured using synthetic capillary medium models (Hele–Shaw cells and microfuidic chips) were comparable with those measured at bulk conditions, the measured vapour pressures in the rock samples (sandstone, limestone, tight sandstone, and shale) were 15% (on average) less than those modelled by PR‑EOS. Abbreviations SAGD Steam assisted gravity drainage C5+ Pentane and higher carbon number hydrocarbons EOR Enhanced oil recovery SOS-FR Steam-over-solvents in fractured reservoir CSS Cyclic steam stimulation EOS Equation-of-state SRP Solvent retrieval process PVT Pressure–volume-temperature CO2 Carbon dioxide PR-EOS Peng–Robinson equation-of-state K Kelvin vL Liquid molar volume r Droplet radius γ Surface tension R Universal gas constant T Temperature P∞ Vapour pressure at fat surface Pr Vapour pressure at curved interface Tr Temperature at porous medium T∞ Temperature at bulk medium Hvap Heat of vaporization Vm Molar volume ZC Critical compressibility factor Department of Civil and Environmental Engineering, School of Mining and Petroleum Engineering, University of Alberta, 7-277 Donadeo Innovation Centre for Engineering, 9211-116th Street, Edmonton, AB T6G 1H9, Canada.
    [Show full text]
  • Design and Performance Analysis of a Modified Vacuum Single Basin Solar Still
    Smart Grid and Renewable Energy, 2011, 2, 388-395 doi:10.4236/sgre.2011.24044 Published Online November 2011 (http://www.SciRP.org/journal/sgre) Design and Performance Analysis of a Modified Vacuum Single Basin Solar Still Moses Koilraj Gnanadason1*, Palanisamy Senthil Kumar2, Gopal Sivaraman3, 4 Joseph Ebenezer Samuel Daniel 1Research Scholar, PRIST University, Thanjavur, India; 2Mechanical Engineering Department, KSR College of Engineering, Ti- ruchengode, India; 3Faculty of Mechanical Engineering, PAAVAI Group of Institutions, Pachel, India; 4Faculty of Mechanical Engi- neering, JACSI College of Engineering, Nazareth, India. Email: *[email protected] Received July 26th, 2011; revised September 23rd, 2011; accepted September 30th, 2011. ABSTRACT Water is essential to life. The origin and continuation of mankind is based on water. The supply of drinking water is an important problem for the developing countries. Among the non-conventional methods to desalinate brackish water or seawater, is solar distillation. The solar still is the most economical way to accomplish this objective. Tamilnadu lies in the high solar radiation band and the vast solar potential can be utilized to convert saline water to potable water. The sun’s energy heats water to the point of evaporation. When water evaporates, water vapour rises leaving the impurities like salts, heavy metals and condensate on the underside of the glass cover. Sunlight has the advantage of zero fuel cost but it requires more space and generally more equipment. Solar distillation has low yield, but safe and pure supplies of water in remote areas. In this context, the design modification of a single basin solar still has been discussed to improve the solar still performance through increasing the production rate of distilled water.
    [Show full text]