Vietnam has a climate with high humidity that often affects the production and storage of goods. When the weather changes, changing the storage place from the production place to the consumers hands, the conditions in each place are different, causing the quality of the product to decrease, fermentation, mold, ... So the study found out the Materials with a hygroscopic ability are essential for businesses. In transportation, especially shipping containers by sea and the use of desiccant material is almost mandatory. Understanding that importance, the group decided to choose the topic desiccant for the subject report. Thereby, somewhat generalized physical and chemical properties as well as application of this material in production technology in general and in particular to heat and cold technology. This essay aims to address the above issues to better understand the desiccant materials and then use them properly to meet the requirements and bring economic efficiency. Since the information has been compiled from many different information sources, the main part is in the textbooks and the internet and has been thoroughly checked by the team members but there are no errors, group 10 looks forward to comment and evaluation. of the master.
DEPARTMENT OF EDUCATION AND TRAINING HCM CITY UNIVERSITY OF TECHNOLOGY EDUCATION FALCUTY OF HIGH QUALITY SUBJECT: THERMAL MATERIALS TOPIC: DESICCANT MATERIAL LECTURER: Group 10 HCM City 11/2020 THERMAL MATERIALS Ph.D Dang Hung Son TEACHER’S ASSETMENT ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… LECTURER’S SIGNATURE THERMAL MATERIALS Ph.D Dang Hung Son CONTENTS INTRODUCTION CHAPTER I: DEFINITION AND CATEGORIZATION OF DESICANT MATERIALS Definition Categorization Requirement CHAPTER II: STRUCTURE AND MAJOR PROPERTIES OF SOME DESICCANT MATERIALS Desiccant materials create mechanical bonds 1.1 Silicagel 1.2 Activated clay 1.3 Zeolite Desiccant material forms hydrated crystals and hydrates 2.1 Calcium chloride 2.2 Calcium sulfate (CaSO4) 2.3 Magnesium percolrate Mg(ClO4)2 Desiccant reacts chemically with water 3.1 CaO (Quicklime) 3.2 Phosphorus pentaoxite (P2O5) Liquid desiccant material 4.1 Ethylenglycol (MEG) 4.2 Diethhylene (DEG) CHAPTER III: APPLICATION OF DESICCANT MATERIALS In industry In refrigeration systems In medical REFERENCE THERMAL MATERIALS Ph.D Dang Hung Son TABLE OF FIGURES Figure 1: Silicagel figure 2: Activated clay in real life Figure 3: Zeolite structure Figure 4: Crystal structure of CaCl2 10 Figure 5: Desiccant powder 11 Figure 6: Desiccant package CaCl2 Figure 7: Crystal structure of CaSO4 Figure 8: Calcium sulfate Figure 9: Crystal structure of Mg(ClO4)2 Figure 10: Desiccant Mg(Clo4)2 Figure 11: Crystal structure of CaO Figure 12: Chemical component of ethyleneglycol Figure 13: Chemical components of C4H10O3 Figure 14: Activated aluminum particles THERMAL MATERIALS Ph.D Dang Hung Son INTRODUCTION Reason for picking this topic Vietnam has a climate with high humidity that often affects the production and storage of goods When the weather changes, changing the storage place from the production place to the consumers' hands, the conditions in each place are different, causing the quality of the product to decrease, fermentation, mold, So the study found out the Materials with a hygroscopic ability are essential for businesses In transportation, especially shipping containers by sea and the use of desiccant material is almost mandatory Understanding that importance, the group decided to choose the topic "desiccant" for the subject report Thereby, somewhat generalized physical and chemical properties as well as application of this material in production technology in general and in particular to heat and cold technology This essay aims to address the above issues to better understand the desiccant materials and then use them properly to meet the requirements and bring economic efficiency Since the information has been compiled from many different information sources, the main part is in the textbooks and the internet and has been thoroughly checked by the team members but there are no errors, group 10 looks forward to comment and evaluation of the master Objective Exploring and collecting information about the properties as well as features of the materials with the ability to absorb moisture In the report, the group will focus on learning about the most common materials Analyze the advantages and disadvantages it brings, make our own objective judgment Research subject and scope Study subjects include fuel cells invented by scientists to improve moisture absorption Scope of research on practical applications at home and abroad Method of evaluation In order to achieve the above objectives, the group will implement the following research methods: Methods of collecting information - Synthesize scientific and objective factors to make some more suggestions DESICCANT MATERIALS THERMAL MATERIALS Ph.D Dang Hung Son CHAPTER I DEFINITION AND CATEGORIZATION OF DESICCANT MATERIALS Definition A desiccant is a hygroscopic substance that is used to induce or sustain a state of dryness (desiccation) in its vicinity Desiccants are durable and inert chemicals, with its useful properties they are produced and widely used in everyday life This substance is widely used in the preservation and transportation of goods, equipment, foods, Categorization Desiccant materials are classified based on the principle of hygroscopicity: • Category 1: Create mechanical bonds with moisture These are materials with tiny holes inside (the size of the hole is only a few Ao), so it is able to retain water + Silicagel SiO2 + Al2O3 activated clay + Zeolite • Classification 2: Creates hydrated crystals and hydrates Materials that have the ability to bind with water + Calcium Sulfate CaSO4 + Calcium chloride CaCl2 + Magnesium Peclorate Mg(ClO4)2 • Classification 3: Chemical reaction with water to form new substances + Lime CaO + Phosphorus Pentaoxit (P2O5) • Class 4: Liquid desiccant + Ethylene glycol (MEG), Diethylene (DEG) DESICCANT MATERIALS THERMAL MATERIALS Ph.D Dang Hung Son Nowadays, science and technology have been inventing a variety of new desiccant materials with higher ability to absorb moisture and improve economic efficiency Requirements for desiccant materials Has a high hygroscopic ability based on the amount of moisture absorbed per unit volume Ability to absorb harmful foreign acids and gases generated in the process Ability to regenerate easily through heat or chemicals Not as a catalyst for harmful reactions Relatively cheap, easy to find In refrigeration system Has a high hygroscopic capacity based on the amount of moisture absorbed per unit of volume even at low steam specific pressure Ability to absorb harmful foreign acids and gases generated during the operation of the refrigeration system The ability to absorb moisture and harmful products does not depend on the temperature within the operating temperature range Do not interact with refrigerants, lubricants, moisture and by-products as well as inorganic and organic machine building materials to create other harmful chemicals Do not act as a catalyst for harmful reactions in refrigeration systems Has a fixed shape, does not fall apart by refrigerant, clogging the throttle and pipes In practice there is no ideal desiccant material One must choose desiccant materials for each application case to take full advantage of their advantages and limit their disadvantages DESICCANT MATERIALS THERMAL MATERIALS Ph.D Dang Hung Son CHAPTER II STRUCTURE AND MAJOR PROPERTIES OF SOME DESICCANT MATERIALS Desiccant materials create mechanical bonds 1.1 Silicagel 1.1.1 General introduction of silicagel Silicagel or silicic acid gel is a very naturally occurring substance, but is actually silicon dioxide Its simple chemical formula is SiO 2.nH2O (n 120% by weight, making the humidity outside the air drop to the maximum quickly, packaging powder packaging Calcium chloride is a two-layer packaging with backflow resistance 2.2 Calcium sulfate (CaSO4) 2.2.1 Concept Calcium sulfate (or calcium sulphate) with chemical formula CaSO is a common industrial and industrial chemical However, it exists in the following three basic forms: anhydrous calcium sulfate (CaSO4), calcium sulfate hemihydrate (CaSO4.0,5H2O) also known as gypsum mortar, Calcium sulphate dihydrate (CaSO 4.2H2O) occurs in nature below plaster form In the γ-anhydride (almost anhydrous form), it is used as a desiccant In nature, calcium sulphate is a translucent, white crystalline rock, a form sold under the name Drierite has a blue or pink color due to its infiltration with cobalt chloride salts, DESICCANT MATERIALS 12 THERMAL MATERIALS Ph.D Dang Hung Son which acts as a substance moisture indicator Melting temperature is 1460°C, solubility in water is 0.24 g / 100 ml (20°C) The crystal structure is orthogonal 2.2.2 Chemical structure and preparation The gypsum powder on the market is usually calcium sulphate hemihydrate or anhydrous calcium sulphate When mixed with water, it will change to a two-water hydrated calcium sulfate phase (CaSO4.2H2O) and harden according to the equation: O CaSO4.0,5H2O + 1,5H2O atm ,160 C CaSO4.2H2O → O or CaSO4 + H2O atm ,160 C CaSO4.2H2O → FIGURE 7: CRYSTAL STRUCTURE OF CASO4 [5] There are many processes that lead to the formation of calcium sulfate As simple as reacting to making H3PO4 in industry: Ca5F (PO4)3 + 5H2SO4 + 10H2O → 5CaSO4.2H2O + 3H3PO4 + HF Or industrial treatment of sulfur dioxide gas emissions by limestone: CaCO3 + SO2 + 0.5H2O → CaSO4.2H2O + CO2 DESICCANT MATERIALS 13 THERMAL MATERIALS Ph.D Dang Hung Son Or the reactions of calcium salts with H2SO4: CaCO3 + H2SO4 + H2O → CaSO4.2H2O + CO2 In the process of producing superphosphate from apatite and limestone ores, the first stage of the reaction forms calcium sulphate as the reaction of H 3PO4 However, it is in the form of hemihydrate, then in the room incubation to hemihydrate will absorb moisture to form gypsum And calcium sulphate is produced during controlled drying of solenoid 2.2.3 Desiccant uses FIGURE 8: CALCIUM SULFATE [6] The ability to absorb moisture is relatively stable, non-toxic, non-abrasive Calcium sulfate compounds (more commercially known as Drierite) are a less expensive alternative that is suitable for packaging types Calcium sulfate is produced by the controlled conditional dehydration of gypsum, which acts as the primary desiccant in the laboratory It is chemically stable, does not release water vapor when it absorbs water vapor when it is exposed to ambient temperature The low value of calcium sulfate depends on its weight relative to its absorbability: it absorbs just over 10% of its weight in water Calcium sulphate also has regenerative properties to the limit of its useful life Although available, it is not usually sold as a packaging DESICCANT MATERIALS 14 THERMAL MATERIALS Ph.D Dang Hung Son The ability to absorb moisture is relatively low in nature, it is often used for making plasters, or shaping in architectural works, making molds in dentistry, making bones and castings, writing boards 2.3 Magnesium percolrate Mg(ClO4)2 2.3.1 Concept Magnesium perchlorate is a powerful oxidizing agent, with the chemical formula specified as Mg(ClO4)2 Odorless, perfect drying compound for gas analysis Magnesium perchlorate decomposes at 250°C The temperature generated from the reaction is 568.90 kJ mol-1, well soluble in water It is sold under the trade name anhydrone 2.3.2 Chemical structure FIGURE 9: CRYSTAL STRUCTURE OF MG(CLO4)2 [7] Mg(ClO4)2 is prepared by the thermal decomposition of the magnesium hexahydrate perchlorate Mg(ClO4)2 • 6H2O → Mg(ClO4)2 + 6H2O 2.3.3 Desiccant uses DESICCANT MATERIALS 15 THERMAL MATERIALS Ph.D Dang Hung Son It is used as a desiccant for drying gas or air samples, but is no longer recommended, for use as a general desiccant, due to the inherent hazards in perchlorate It is dried by heating at 220°C in vacuum FIGURE 10: DESICCANT MG(CLO4)2 [8] Desiccant reacts chemically with water 3.1 CaO (Quicklime) 3.1.1 Introduction Calcium oxide (CaO formula, also known as calcium, other common names are quicklime, calcined lime) is an oxide of calcium, which is widely used It has a molar mass of 56.1 g/mol, thermal expansion coefficient 0.148, melting point 2572°C It is a white crystalline solid and is caustic and alkaline As a commercial product, quicklime contains both magnesium oxide (MgO), silicon oxide SiO2 and small amounts of aluminum oxide Al2O3 and iron (II) FeO oxide DESICCANT MATERIALS 16