Psychrometry: Properties and processes discusses key concepts in psychrometry including:
- Psychrometry is the study of properties of air-water vapor mixtures, commonly known as moist air. Moist air consists of dry air, water vapor, and other inert gases.
- Key psychrometric properties include specific humidity, relative humidity, dry bulb temperature, wet bulb temperature, dew point temperature, and degree of saturation.
- The sling psychrometer is used to measure wet bulb temperature by whirling two thermometers, one dry and one wet, through the air. Wet bulb depression indicates the specific humidity of air.
- Dew point temperature is the temperature at which air becomes saturated when cooled at constant
In any thermal power generation plant, heat energy converts into mechanical work. Then it is converted to electrical energy by rotating a generator which produces electrical energy.
This document discusses psychrometry, which is the study of thermodynamic properties of moist air. It outlines several important psychrometric properties used to analyze air conditioning processes, including dry bulb temperature, wet bulb temperature, dew point temperature, humidity ratio, relative humidity, specific volume, and enthalpy. It then explains common psychrometric processes like sensible heating, sensible cooling, humidification, dehumidification, and their representations on a psychrometric chart. Basic concepts in air conditioning like adiabatic mixing, bypass factor, sensible heat factor, and room sensible heat factor are also introduced.
Pump Cavitation & Net Positive Suction HeadHasnaın Sheıkh
This document summarizes key concepts related to pump cavitation and net positive suction head (NPSH). It defines cavitation as the formation of vapor bubbles when local pressure inside a pump drops below the vapor pressure of the liquid. Repeated cavitation can damage impeller blades through pitting and erosion. NPSH is introduced to quantify the pressure required to avoid cavitation. NPSH available considers the inlet pressure accounting for piping losses, while NPSH required is provided by pump manufacturers as the minimum pressure needed. The document outlines how NPSH available and required values vary with flow rate and other variables like liquid temperature.
The document provides lecture notes on steam nozzles and power plants. It discusses:
1) The basic components and energy conversion process in thermal power plants, including the Rankine cycle in which water is heated to steam to power a turbine and generator.
2) The history and development of steam turbines, from early aeolipile devices to modern turbines invented by Charles Parsons in 1884.
3) How energy is converted in steam turbines via nozzles that accelerate steam to high velocity to impulse turbine blades and produce rotation.
4) Details on nozzle types, flow properties, relationships between area, velocity and pressure, and equations for calculating velocity from enthalpy change.
Boilers are most important part of Chemical Industry. 99 % boilers used in Pakistan Chemical Industries are water tube boilers because of their high efficiency and safety. So we should have clear understanding about the boilers.
Psychrometry is the science dealing with air-water vapor mixtures. It studies moist air and its properties like dew point temperature, relative humidity, and dry/wet bulb temperatures. Psychrometric processes involve changes to moist air through sensible heating/cooling, humidifying, dehumidifying, and adiabatic mixing/cooling. The psychrometric chart is used to analyze these processes by plotting air properties and showing lines for temperature, humidity, and enthalpy. It is a useful tool for understanding air conditioning systems and classifying climates.
1) A reciprocating compressor takes in air or gas at low pressure and compresses it using pistons moving back and forth in cylinders.
2) It is classified based on design, number of stages, pressure ratio, capacity, number of cylinders, type of fluid, and cooling method.
3) In single stage reciprocating compression, air is drawn into the cylinder on the inward stroke and compressed on the outward stroke through inlet and outlet valves.
This document provides an overview of psychrometry, which is the study of air and water vapor mixtures. It defines important psychrometric properties like dry bulb temperature, wet bulb temperature, humidity ratio, and enthalpy. It explains psychrometric processes like sensible heating, cooling, and humidification. The psychrometric chart is introduced as a tool to represent the thermodynamic properties of moist air. Common psychrometric devices like air washers are also discussed.
In any thermal power generation plant, heat energy converts into mechanical work. Then it is converted to electrical energy by rotating a generator which produces electrical energy.
This document discusses psychrometry, which is the study of thermodynamic properties of moist air. It outlines several important psychrometric properties used to analyze air conditioning processes, including dry bulb temperature, wet bulb temperature, dew point temperature, humidity ratio, relative humidity, specific volume, and enthalpy. It then explains common psychrometric processes like sensible heating, sensible cooling, humidification, dehumidification, and their representations on a psychrometric chart. Basic concepts in air conditioning like adiabatic mixing, bypass factor, sensible heat factor, and room sensible heat factor are also introduced.
Pump Cavitation & Net Positive Suction HeadHasnaın Sheıkh
This document summarizes key concepts related to pump cavitation and net positive suction head (NPSH). It defines cavitation as the formation of vapor bubbles when local pressure inside a pump drops below the vapor pressure of the liquid. Repeated cavitation can damage impeller blades through pitting and erosion. NPSH is introduced to quantify the pressure required to avoid cavitation. NPSH available considers the inlet pressure accounting for piping losses, while NPSH required is provided by pump manufacturers as the minimum pressure needed. The document outlines how NPSH available and required values vary with flow rate and other variables like liquid temperature.
The document provides lecture notes on steam nozzles and power plants. It discusses:
1) The basic components and energy conversion process in thermal power plants, including the Rankine cycle in which water is heated to steam to power a turbine and generator.
2) The history and development of steam turbines, from early aeolipile devices to modern turbines invented by Charles Parsons in 1884.
3) How energy is converted in steam turbines via nozzles that accelerate steam to high velocity to impulse turbine blades and produce rotation.
4) Details on nozzle types, flow properties, relationships between area, velocity and pressure, and equations for calculating velocity from enthalpy change.
Boilers are most important part of Chemical Industry. 99 % boilers used in Pakistan Chemical Industries are water tube boilers because of their high efficiency and safety. So we should have clear understanding about the boilers.
Psychrometry is the science dealing with air-water vapor mixtures. It studies moist air and its properties like dew point temperature, relative humidity, and dry/wet bulb temperatures. Psychrometric processes involve changes to moist air through sensible heating/cooling, humidifying, dehumidifying, and adiabatic mixing/cooling. The psychrometric chart is used to analyze these processes by plotting air properties and showing lines for temperature, humidity, and enthalpy. It is a useful tool for understanding air conditioning systems and classifying climates.
1) A reciprocating compressor takes in air or gas at low pressure and compresses it using pistons moving back and forth in cylinders.
2) It is classified based on design, number of stages, pressure ratio, capacity, number of cylinders, type of fluid, and cooling method.
3) In single stage reciprocating compression, air is drawn into the cylinder on the inward stroke and compressed on the outward stroke through inlet and outlet valves.
This document provides an overview of psychrometry, which is the study of air and water vapor mixtures. It defines important psychrometric properties like dry bulb temperature, wet bulb temperature, humidity ratio, and enthalpy. It explains psychrometric processes like sensible heating, cooling, and humidification. The psychrometric chart is introduced as a tool to represent the thermodynamic properties of moist air. Common psychrometric devices like air washers are also discussed.
This document discusses psychrometry and air conditioning. It begins by defining dry air and atmospheric air, and the specific and relative humidity of air. It then discusses dew point temperature and how to calculate it. The document introduces the psychrometric chart as a tool to determine air properties and outlines several air conditioning processes like heating, cooling, humidification and dehumidification. Key concepts like wet bulb temperature, adiabatic saturation and human comfort are also summarized. Specific air conditioning applications such as evaporative cooling, mixing of air streams and cooling towers are briefly described.
Psychrometry is the study of air-water vapor mixtures. It examines properties like dew point temperature, relative humidity, and dry/wet bulb temperatures. Key psychrometric processes include sensible heating/cooling which changes temperature without altering moisture content, and dehumidification/humidification which remove or add moisture through heat transfer. Adiabatic cooling involves evaporative cooling without heat loss, while adiabatic mixing describes combining air streams without a net heat change. Psychrometric charts graphically depict these processes and climate zones.
Steam boilers are closed vessels that produce steam from water through fuel combustion. They are used to power steam engines and turbines or for heating. Key boiler components include the shell, furnace, and mountings. Accessories like economizers and superheaters improve efficiency. Boilers require safe containment of water and delivery of steam at the desired pressure and quality. Common boiler terms are defined and the purposes of accessories and mountings like pressure gauges and fusible plugs are described.
This document describes the design of a plant for cryogenic distillation of air into oxygen and nitrogen. It includes an introduction to air separation and the cryogenic process. Process equipment like compressors, heat exchangers, and distillation columns are designed. Mass and energy balances are performed. The distillation columns and condenser are designed and specifications are provided. An economic analysis includes capital costs, production costs, profitability metrics, payback period and safety considerations. References for design methods are also listed.
Positive displacement pumps move fluids by trapping a fixed volume and forcing that volume from the suction to discharge side. Reciprocating pumps, like piston pumps, use reciprocating motion powered by engines while rotary pumps use rotating components like gears or lobes. Piston pumps have two check valves and a reciprocating piston powered by translating rotary motion into linear motion. They can be direct or indirect acting, simplex or duplex, and single or double acting. Diaphragm pumps use a flexible diaphragm instead of pistons. Rotary pumps have gears, lobes, screws, cams, or vanes that rotate to trap and move fluid and include gear, lobe, screw, vane, and cam pumps
INTRODUCTION
THERMODYNAMIC CYCLE OF STEAM FLOW
RANKINE CYCLE (IDEAL , ACTUAL ,REHEAT)
LAYOUT OF STEAM POWER PLANT
MAJOR COMPONENTS AND THEIR FUNCTIONS
ALTERNATOR
EXCITATION SYSTEM
GOVERNING SYSTEM
Steam jet ejectors provide vacuum using high-pressure steam as the motive fluid, requiring no external power source. They have no moving parts, making them reliable and easy to maintain. Ejectors work by accelerating steam through a converging-diverging nozzle, which entrains the suction fluid and recompresses it at an intermediate pressure through a diffuser. Ejectors can be single or multi-stage, with condensers used to improve efficiency, and are well-suited for applications that require vacuum where steam is readily available such as drying and distillation.
The document discusses psychrometric charts and their use in analyzing air conditioning processes and calculating air properties. It provides an example problem of calculating properties for an air sample with a dry bulb temperature of 40°C and wet bulb temperature of 28°C. It also discusses sensible and latent heating/cooling, mixing of air streams, and includes sample problems calculating psychrometric properties and air conditioning system design values.
Try to explain about the steam generator (boiler), it has three parts. Part 1 cover the types, part 2 about its parts & auxiliaries & accessories and part 3 about performance.
This document outlines the key topics to be covered in a course on psychrometry and air conditioning. It will discuss psychrometric terms and relations, psychrometric charts and processes, air conditioning components and equipment, air conditioning systems and controls, factors affecting human comfort, and load estimation and duct design. It provides examples to illustrate psychrometric concepts and calculations involving dry bulb temperature, wet bulb temperature, relative humidity, specific humidity, enthalpy, and other psychrometric properties. It also describes common air conditioning processes, equipment, and system types.
An economiser is a device that increases the temperature of feed water using waste heat from flue gases leaving the boiler. It consists of vertical cast iron or steel pipes through which feed water flows and is heated by hot flue gases passing over the pipes. This preheats the feed water, reducing fuel consumption and increasing boiler efficiency. However, economisers also cause a pressure drop in flue gases. An air preheater similarly uses waste heat to preheat combustion air entering the furnace, improving combustion and efficiency but requiring forced draught.
This document provides information about boilers. It defines a boiler as a closed vessel that heats fluid, typically water, which is then used for various heating applications. It describes the basic working principle of boilers, which involves using heat energy to convert water into steam. It also discusses different boiler types, components like burners, pumps, and safety devices, and explains the basic sequence of operations for a boiler.
Hello,
I am trying to explain about Steam Generator (Boiler) in this session, due to length of said presentation, I am deciding to divide it in three parts.
Part 1 cover the “Introduction & Types of Steam Generator”
Part 2 cover about the “Parts of Steam Generator and Its Accessories & Auxiliaries” and
Part 3 cover the “Efficiency & Performance”
When altitude increases, water's boiling point decreases as pressure drops. For every 27mmHg increase in pressure, boiling point rises 1°C. Water vaporizes based on temperature and pressure. NPSHa is the available positive suction head, calculated as total suction head minus vapor pressure. NPSHR is the required positive suction head to avoid cavitation. Cavitation can damage pumps when NPSHa is less than NPSHR. Engineers must ensure sufficient margin between liquid and vapor states.
This document provides information about steam nozzles and steam turbines. It discusses:
1. Steam nozzles convert the heat energy of steam into kinetic energy by accelerating steam through a passage of varying cross-section.
2. Steam turbines convert the high-pressure, high-temperature steam from a steam generator into rotational shaft work.
3. There are three main types of nozzles used in steam turbines: convergent, divergent, and convergent-divergent. Convergent-divergent nozzles are widely used today.
4. The document then discusses concepts like Mach number and critical pressure that are important for steam nozzle and turbine operation.
The document discusses centrifugal pumps. It describes how centrifugal pumps work by converting mechanical energy to hydraulic energy using centrifugal force. They work on the principle of forced vortex flow. Key components include an impeller that rotates and accelerates the fluid outward, and a casing that captures the fluid and converts its kinetic energy to pressure. Centrifugal pumps are used to pump liquids like water, sewage, petroleum and more. Performance curves are used to predict pump behavior under different operating conditions.
Centrifugal compressors work by imparting kinetic energy to a gas stream using an impeller, converting the dynamic energy into increased static pressure. They have advantages like high throughput capacity and efficiency over a wide operating range, but also disadvantages like discharge pressure limitations. Key components include impellers, diffusers, volutes, casings, shafts, bearings, and seals. Surge, a dangerous condition where flow reverses rapidly, must be controlled. Compressors can operate alone or in multi-stage arrangements with intercoolers. Common drivers are steam turbines, electric motors, and gas turbines.
This document discusses psychrometric terms and relations. It defines dry air, moist air, saturated air, degree of saturation, humidity, absolute humidity, relative humidity, dry bulb temperature, wet bulb temperature, wet bulb depression, dew point temperature, dew point depression, and psychrometer. It describes Dalton's law of partial pressures and key psychrometric relations regarding specific humidity, degree of saturation, relative humidity, pressure of water vapor, and absolute humidity. An example problem is included to demonstrate calculating relative humidity, specific humidity, dew point temperature, enthalpy per kg of dry air, and volume of air mixture per kg of dry air given dry bulb temperature, wet bulb temperature, and barometric pressure.
This document discusses psychrometry, which is the study of moist air mixtures. It defines key terms like dry air, moist air, saturated air, humidity ratio, relative humidity, dry bulb temperature, wet bulb temperature, and dew point temperature. It describes Dalton's law of partial pressures as it applies to air-vapor mixtures. It also outlines important psychrometric relationships between specific humidity, degree of saturation, relative humidity, vapor pressure, and absolute humidity. Sample problems are provided to demonstrate how to use psychrometric charts and equations to determine properties like dew point, relative humidity, specific humidity, enthalpy, and volume from measurements of dry bulb temperature, wet bulb temperature, and barometric pressure.
This document discusses psychrometry and air conditioning. It begins by defining dry air and atmospheric air, and the specific and relative humidity of air. It then discusses dew point temperature and how to calculate it. The document introduces the psychrometric chart as a tool to determine air properties and outlines several air conditioning processes like heating, cooling, humidification and dehumidification. Key concepts like wet bulb temperature, adiabatic saturation and human comfort are also summarized. Specific air conditioning applications such as evaporative cooling, mixing of air streams and cooling towers are briefly described.
Psychrometry is the study of air-water vapor mixtures. It examines properties like dew point temperature, relative humidity, and dry/wet bulb temperatures. Key psychrometric processes include sensible heating/cooling which changes temperature without altering moisture content, and dehumidification/humidification which remove or add moisture through heat transfer. Adiabatic cooling involves evaporative cooling without heat loss, while adiabatic mixing describes combining air streams without a net heat change. Psychrometric charts graphically depict these processes and climate zones.
Steam boilers are closed vessels that produce steam from water through fuel combustion. They are used to power steam engines and turbines or for heating. Key boiler components include the shell, furnace, and mountings. Accessories like economizers and superheaters improve efficiency. Boilers require safe containment of water and delivery of steam at the desired pressure and quality. Common boiler terms are defined and the purposes of accessories and mountings like pressure gauges and fusible plugs are described.
This document describes the design of a plant for cryogenic distillation of air into oxygen and nitrogen. It includes an introduction to air separation and the cryogenic process. Process equipment like compressors, heat exchangers, and distillation columns are designed. Mass and energy balances are performed. The distillation columns and condenser are designed and specifications are provided. An economic analysis includes capital costs, production costs, profitability metrics, payback period and safety considerations. References for design methods are also listed.
Positive displacement pumps move fluids by trapping a fixed volume and forcing that volume from the suction to discharge side. Reciprocating pumps, like piston pumps, use reciprocating motion powered by engines while rotary pumps use rotating components like gears or lobes. Piston pumps have two check valves and a reciprocating piston powered by translating rotary motion into linear motion. They can be direct or indirect acting, simplex or duplex, and single or double acting. Diaphragm pumps use a flexible diaphragm instead of pistons. Rotary pumps have gears, lobes, screws, cams, or vanes that rotate to trap and move fluid and include gear, lobe, screw, vane, and cam pumps
INTRODUCTION
THERMODYNAMIC CYCLE OF STEAM FLOW
RANKINE CYCLE (IDEAL , ACTUAL ,REHEAT)
LAYOUT OF STEAM POWER PLANT
MAJOR COMPONENTS AND THEIR FUNCTIONS
ALTERNATOR
EXCITATION SYSTEM
GOVERNING SYSTEM
Steam jet ejectors provide vacuum using high-pressure steam as the motive fluid, requiring no external power source. They have no moving parts, making them reliable and easy to maintain. Ejectors work by accelerating steam through a converging-diverging nozzle, which entrains the suction fluid and recompresses it at an intermediate pressure through a diffuser. Ejectors can be single or multi-stage, with condensers used to improve efficiency, and are well-suited for applications that require vacuum where steam is readily available such as drying and distillation.
The document discusses psychrometric charts and their use in analyzing air conditioning processes and calculating air properties. It provides an example problem of calculating properties for an air sample with a dry bulb temperature of 40°C and wet bulb temperature of 28°C. It also discusses sensible and latent heating/cooling, mixing of air streams, and includes sample problems calculating psychrometric properties and air conditioning system design values.
Try to explain about the steam generator (boiler), it has three parts. Part 1 cover the types, part 2 about its parts & auxiliaries & accessories and part 3 about performance.
This document outlines the key topics to be covered in a course on psychrometry and air conditioning. It will discuss psychrometric terms and relations, psychrometric charts and processes, air conditioning components and equipment, air conditioning systems and controls, factors affecting human comfort, and load estimation and duct design. It provides examples to illustrate psychrometric concepts and calculations involving dry bulb temperature, wet bulb temperature, relative humidity, specific humidity, enthalpy, and other psychrometric properties. It also describes common air conditioning processes, equipment, and system types.
An economiser is a device that increases the temperature of feed water using waste heat from flue gases leaving the boiler. It consists of vertical cast iron or steel pipes through which feed water flows and is heated by hot flue gases passing over the pipes. This preheats the feed water, reducing fuel consumption and increasing boiler efficiency. However, economisers also cause a pressure drop in flue gases. An air preheater similarly uses waste heat to preheat combustion air entering the furnace, improving combustion and efficiency but requiring forced draught.
This document provides information about boilers. It defines a boiler as a closed vessel that heats fluid, typically water, which is then used for various heating applications. It describes the basic working principle of boilers, which involves using heat energy to convert water into steam. It also discusses different boiler types, components like burners, pumps, and safety devices, and explains the basic sequence of operations for a boiler.
Hello,
I am trying to explain about Steam Generator (Boiler) in this session, due to length of said presentation, I am deciding to divide it in three parts.
Part 1 cover the “Introduction & Types of Steam Generator”
Part 2 cover about the “Parts of Steam Generator and Its Accessories & Auxiliaries” and
Part 3 cover the “Efficiency & Performance”
When altitude increases, water's boiling point decreases as pressure drops. For every 27mmHg increase in pressure, boiling point rises 1°C. Water vaporizes based on temperature and pressure. NPSHa is the available positive suction head, calculated as total suction head minus vapor pressure. NPSHR is the required positive suction head to avoid cavitation. Cavitation can damage pumps when NPSHa is less than NPSHR. Engineers must ensure sufficient margin between liquid and vapor states.
This document provides information about steam nozzles and steam turbines. It discusses:
1. Steam nozzles convert the heat energy of steam into kinetic energy by accelerating steam through a passage of varying cross-section.
2. Steam turbines convert the high-pressure, high-temperature steam from a steam generator into rotational shaft work.
3. There are three main types of nozzles used in steam turbines: convergent, divergent, and convergent-divergent. Convergent-divergent nozzles are widely used today.
4. The document then discusses concepts like Mach number and critical pressure that are important for steam nozzle and turbine operation.
The document discusses centrifugal pumps. It describes how centrifugal pumps work by converting mechanical energy to hydraulic energy using centrifugal force. They work on the principle of forced vortex flow. Key components include an impeller that rotates and accelerates the fluid outward, and a casing that captures the fluid and converts its kinetic energy to pressure. Centrifugal pumps are used to pump liquids like water, sewage, petroleum and more. Performance curves are used to predict pump behavior under different operating conditions.
Centrifugal compressors work by imparting kinetic energy to a gas stream using an impeller, converting the dynamic energy into increased static pressure. They have advantages like high throughput capacity and efficiency over a wide operating range, but also disadvantages like discharge pressure limitations. Key components include impellers, diffusers, volutes, casings, shafts, bearings, and seals. Surge, a dangerous condition where flow reverses rapidly, must be controlled. Compressors can operate alone or in multi-stage arrangements with intercoolers. Common drivers are steam turbines, electric motors, and gas turbines.
This document discusses psychrometric terms and relations. It defines dry air, moist air, saturated air, degree of saturation, humidity, absolute humidity, relative humidity, dry bulb temperature, wet bulb temperature, wet bulb depression, dew point temperature, dew point depression, and psychrometer. It describes Dalton's law of partial pressures and key psychrometric relations regarding specific humidity, degree of saturation, relative humidity, pressure of water vapor, and absolute humidity. An example problem is included to demonstrate calculating relative humidity, specific humidity, dew point temperature, enthalpy per kg of dry air, and volume of air mixture per kg of dry air given dry bulb temperature, wet bulb temperature, and barometric pressure.
This document discusses psychrometry, which is the study of moist air mixtures. It defines key terms like dry air, moist air, saturated air, humidity ratio, relative humidity, dry bulb temperature, wet bulb temperature, and dew point temperature. It describes Dalton's law of partial pressures as it applies to air-vapor mixtures. It also outlines important psychrometric relationships between specific humidity, degree of saturation, relative humidity, vapor pressure, and absolute humidity. Sample problems are provided to demonstrate how to use psychrometric charts and equations to determine properties like dew point, relative humidity, specific humidity, enthalpy, and volume from measurements of dry bulb temperature, wet bulb temperature, and barometric pressure.
Pschometry and psychometric properties.pptxbaghbana bajoi
what is Psychrometric?
Psychrometry is a branch of science in which we study the thermodynamics of air and moisture with primary objective of developing human comfort.
=> Saturated air. Saturated air is a saturated mixture of air and water vapor mixture, where the vapor is at the saturation temperature and pressure.
FOR EXAMPLE :
when we feel thirsty,we need water to quench the thirsty, similarly air also feel thirsty and it need water to quench it thirsty or air has affinity to absorb the water
When temperature is high, so causes the air feel more thirsty.
=> Saturated air;
Saturated air is that air which holds water vapour at its maximum concentration at a particular temperature and pressure.
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Psychrometry is the study of air-water vapor mixtures. Key terms include:
- Dry bulb temperature (DBT) - measured by ordinary thermometer
- Wet bulb temperature (WBT) - measured by thermometer wrapped in wet cloth
- Dew point temperature (DPT) - temperature at which moisture condenses
- Relative humidity (RH) - ratio of actual water vapor to maximum possible at given DBT
An adiabatic saturator is used to measure the thermodynamic wet bulb temperature, which is the temperature air reaches when saturated adiabatically. Multiple inlet air conditions can result in the same thermodynamic wet bulb temperature.
The document is about psychrometrics and air conditioning processes. It discusses key psychrometric concepts like dry bulb temperature, wet bulb temperature, dew point temperature, humidity ratios and enthalpy. It explains common air conditioning processes like sensible heating and cooling, humidification, dehumidification, cooling with dehumidification. The psychrometric chart is introduced which graphically represents the thermodynamic properties of moist air. Common terms used in psychrometrics like by-pass factor and sensible heat factor are also defined.
This document discusses air conditioning and psychrometrics. It defines air conditioning as controlling temperature, humidity, and other factors to provide human comfort. Psychrometry is introduced as the study of moist air and its properties. Key psychrometric terms are defined, including dry bulb temperature, wet bulb temperature, humidity, and dew point temperature. Dalton's law of partial pressures is described as it applies to moist air. The main psychrometric processes used in air conditioning are outlined, such as sensible heating and cooling, humidification, and dehumidification. Bypass factor is also introduced in relation to heating and cooling coils.
The psychrometric chart is a readable chart used in sizing typical air conditioning systems. It relates temperature, humidity, enthalpy, and other properties of moist air on a single graph. The basic features include dry-bulb temperature on the x-axis and specific humidity on the y-axis. Lines of constant wet-bulb temperature, specific volume, and enthalpy are also included. The saturation line represents the curve of 100% relative humidity. Psychrometric charts can be used to determine various air properties if two variables like dry-bulb temperature and relative humidity are known. They also allow analysis of different air conditioning processes that change the condition of air, such as constant latent heat, constant sensible heat, and ad
Psychrometry is the study of air-water vapor mixtures. It is important for air conditioning design to understand the properties of atmospheric air, which is a mixture of gases, water vapor, and pollutants. Specific humidity refers to the mass of water associated with each kilogram of dry air. Key psychrometric processes used in air conditioning include:
1) Sensible cooling, where air temperature decreases over a cooling coil while moisture content remains constant.
2) Heating and humidification, where air is first sensibly heated and then water vapor is added through steam nozzles.
3) Cooling and humidification, where air temperature and humidity both increase by spraying cool water into the air stream
The document defines key terms related to psychrometrics, which is the science of moist air properties and processes. It explains that atmospheric air contains a mixture of gases including nitrogen, oxygen, carbon dioxide and water vapor. Moist air contains both air and water vapor, while saturated air contains the maximum possible amount of water vapor. Other terms defined include humidity, dry bulb temperature, wet bulb temperature, relative humidity, vapor pressure, specific humidity, dew point temperature, and enthalpy. The document concludes by explaining that a psychrometric chart graphically represents various psychrometric properties and processes on a single plot.
Psychrometry ala rac gtu sem 6th Refrigeration and Air conditioningShrey Patel
pshchrometry
refrigeration and air conditioning
BE Mechanical 6th sem ALA ppt
GTU MSU
various terms related to psychrometry and psychrometric chart with example
Humidifier
Terminology : psychometry , absolute humidity , relative humidity , dew point , wet bulb temperature , adiabatic saturation temperature
Dehumidifier
Psychometric chart and its uses
Measurement of humidity
Application of humidity control
Psicrometría es la ciencia que estudia las propiedades termodinámicas del aire húmedo y el efecto de la humedad atmosférica. El documento explica que la psicrometría permite medir y controlar la humedad del aire a través del uso de tablas o cartas psicrométricas, las cuales representan variables como la temperatura de bulbo seco, húmedo y de rocío. Finalmente, señala que la carta psicrométrica es una herramienta fundamental para el acondicionamiento de aire
Humidity refers to the amount of water vapor in the air. It can be measured using instruments like a psychrometer, which uses the difference between dry and wet bulb thermometer readings. Relative humidity indicates the percentage of water vapor an air sample can hold compared to its maximum capacity. Other expressions of humidity include vapor pressure, absolute humidity, dewpoint, specific humidity, and mixing ratio. Proper measurement requires accounting for factors like temperature fluctuations, instrument errors, and air ventilation.
The document discusses atmospheric humidity and related concepts. It defines humidity as the amount of water vapor in the air, and notes that humidity varies due to evaporation and condensation. Instruments like psychrometers are used to measure humidity by determining the difference between wet and dry bulb temperatures. The document also examines vapor pressure, dew point, relative humidity, and other terms, and how humidity levels fluctuate over time due to factors like temperature changes and the seasons.
This document discusses gas vapor mixtures and dry air/atmospheric air in air conditioning analysis. It defines dry air as air without moisture and atmospheric air as a mixture of dry air and water vapor. Specific and relative humidity are introduced to quantify the amount of moisture in air. Specific humidity is the ratio of water vapor mass to dry air mass, while relative humidity compares the actual water vapor mass to the saturated mass at the same temperature and pressure. The dew point temperature is defined as the temperature when air is cooled at constant pressure until condensation starts. Adiabatic saturation temperature is related to wet-bulb temperature. Finally, psychrometric charts are introduced to specify the state of air using two intensive properties.
The document discusses psychrometry, which is the study of moist air and humidity. Specifically, it defines key terms related to psychrometry including dry air, moist air, saturated air, humidity, absolute humidity, relative humidity, dry bulb temperature, wet bulb temperature, and dew point temperature. It also explains concepts such as degree of saturation, Dalton's law of partial pressures, and provides details on how various psychrometric properties are measured or defined.
This document provides an overview of psychrometry, which is the study of air properties and humidity. It defines key terms like dry air, moist air, vapor pressure, and saturation pressure. The document discusses:
1. The composition of air as a mixture of dry air and water vapor. Dry air consists mainly of nitrogen and oxygen.
2. Gas laws and properties that apply to air mixtures, including partial pressures, molecular weights, specific heats, and Dalton's law.
3. Psychrometric properties of moist air like total pressure, vapor pressure, and saturation pressure at the wet bulb temperature.
4. The objectives of the lecture are to define important psychrometric concepts and properties, explain
This document discusses psychrometry, which is the study of atmospheric air and its associated water vapor. It defines key terms like dew point temperature, dry-bulb temperature, wet-bulb temperature, humidity ratio, and different types of humidity. It also explains the psychrometric chart, which graphically presents the physical and thermal properties of moist air. Key properties discussed include dew point, dry-bulb temperature, wet-bulb temperature, saturation line, and relative humidity.
TOPIC OF APPLIED THERMODYNAMICS:
ANALYSIS OF CONDENSER OPERATION
VACUUM CREATION
DALTONS LAW OF PARTIAL PRESSURE,
SOURCES OF AIR IN THE CONDENSER,
EFFECT OF AIR LEAKAGE INTO CONDENSER,
This document provides an overview of the major components and processes involved in a coal-based thermal power plant. It discusses the key circuits in the plant including coal/ash handling, air/gas, feedwater/steam, and cooling water. It also describes site selection factors and the functions of major equipment like boilers, turbines, condensers, and cooling towers. Key coal preparation and ash removal processes are explained. Finally, it covers supercritical boilers and defines important thermal power plant concepts like steam rate and heat rate.
This document discusses rocket propulsion and solid rocket motors. It defines propulsion as initiating or changing the motion of a body. Rocket propulsion works by ejecting propellant to create a reaction force and induce motion. Solid rocket motors use solid propellants composed of fuel, oxidizer, and binder. They provide high thrust but have low control and cannot be shut down and restarted. Performance is measured by parameters like specific impulse, total impulse, and effective exhaust velocity.
1. The document provides information about normal and oblique shock waves, including: Normal shock waves occur when flow is perpendicular to the shock and changes flow direction, while oblique shock waves occur at an angle and can change the flow direction.
2. Equations of motion are derived using conservation of mass, momentum, and energy across a control volume around the shock. These result in relations that allow calculation of flow properties downstream using upstream conditions and shock angle.
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solve this issue, this paper develops a hybrid Deep Learning (DL) model specifically designed for intrusion
detection in smart grids. The proposed approach is a combination of the Convolutional Neural Network
(CNN) and the Long-Short-Term Memory algorithms (LSTM). We employed a recent intrusion detection
dataset (DNP3), which focuses on unauthorized commands and Denial of Service (DoS) cyberattacks, to
train and test our model. The results of our experiments show that our CNN-LSTM method is much better
at finding smart grid intrusions than other deep learning algorithms used for classification. In addition,
our proposed approach improves accuracy, precision, recall, and F1 score, achieving a high detection
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The growing significance of portable systems to limit power consumption in ultra-large-scale-integration chips of very high density, has recently led to rapid and inventive progresses in low-power design. The most effective technique is adiabatic logic circuit design in energy-efficient hardware. This paper presents two adiabatic approaches for the design of low power circuits, modified positive feedback adiabatic logic (modified PFAL) and the other is direct current diode based positive feedback adiabatic logic (DC-DB PFAL). Logic gates are the preliminary components in any digital circuit design. By improving the performance of basic gates, one can improvise the whole system performance. In this paper proposed circuit design of the low power architecture of OR/NOR, AND/NAND, and XOR/XNOR gates are presented using the said approaches and their results are analyzed for powerdissipation, delay, power-delay-product and rise time and compared with the other adiabatic techniques along with the conventional complementary metal oxide semiconductor (CMOS) designs reported in the literature. It has been found that the designs with DC-DB PFAL technique outperform with the percentage improvement of 65% for NOR gate and 7% for NAND gate and 34% for XNOR gate over the modified PFAL techniques at 10 MHz respectively.
A review on techniques and modelling methodologies used for checking electrom...nooriasukmaningtyas
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1. Psychrometry: Properties and processes
B.Prabhu, T.Suresh & P.Selvan
Assistant Professor - Mechanical Engineering
Kamaraj College of Engineering of Technology
Virudhunagar
2. Psychrometry - Introduction
Different gas-vapour mixtures are encountered in many engineering
applications and air-water vapour mixture is the most commonly encountered
gas-vapour mixture in practice.
air-conditioning of Air-water vapour mixtures play a dominant role in the
manufacturing plants and food preservation plants.
A special field of study called ‘Psychrometry’ is evolved to study the
properties of air-water vapour mixtures .
A common example of air-water vapour mixture is the moist atmospheric air.
3. Moist Air
It is a mixture of dry air, water vapour and few other inert gases (such as argon, neon,
krypton, helium etc.) whose percentage is negligible.
Hence air is regarded only as a mixture of dry air and water vapour.
Dry air is considered to consist of 21% oxygen and 79% nitrogen by volume.
The water vapour normally exists in a saturated or superheated condition in the
atmospheric air.
4. DRY AND ATMOSPHERIC AIR
Atmospheric air: Air in the atmospherecontaining
some water vapor (or moisture).
Dry air: Air that contains no water vapor.
Water vapor in the air plays a major role in human
comfort. Therefore, it is an important consideration in
air-conditioning applications.
Water vapor in air behaves as if it existed alone and
obeys the ideal-gas relation Pv = RT. Then the
atmospheric air can be treated as an ideal-gas mixture:
The cp of air can be
assumed to be constant
at 1.005 kJ/kg·°C in the
temperature range 10
to 50°C with an error
under 0.2%.
5. Moist air ….
The amount of water vapour changes due to condensation by cooling or added to the
air by vaporization from a large water surface.
Hence it forms a changing part in the moist air while the dry air forms a fixed part.
The partial pressure of water vapour present in the atmospheric air is very low and at
such low pressures, the water vapour may be treated as an ideal gas.
At 40C, the saturation pressure of water is 7.38 kPa at such low pressures the water
vapour can be treated as ideal gas with negligible error(below 0.2%).
The dry air behaves almost as an ideal gas.
Hence the atmospheric air can be treated as a mixture of ideal gases.
6. Psychometric properties
The properties of air-water vapour mixture i.e. moist air are termed its psychometric
properties
and the subject dealing with the same is named ‘Psychrometry’.
The following definitions are used in the study of moist air:
7. Vapour pressure and saturation vapour pressure
Vapor pressure is the independent pressure exerted by the water vapor in the air.
The vapor pressure is proportional to the humidity ratio.
The natural tendency for pressures to equalize will cause moisture to migrate from an
area of high vapour pressure to an area of low vapor pressure.
The saturation vapour pressure varies with temperature.
Saturation vapor pressure (Psat) is the maximum possible vapor pressure for air at
some temperature (ignoring the possibility of super saturation).
At any one time the actual vapor pressure Pw could be anything between 0 and Psat.
8. Specific humidity or absolute humidity or
humidity ratio
(denoted by ) Specific humidity is the ratio of the mass of water vapour present to the mass
of dry air in a given volume of the moist air at a given temperature.
=mV /ma Specific humidity of moist air
Where
mV - mass of water vapour in a given volume of moist air at temperature T
ma - mass of dry air in the same volume of moist air at the same temperature
mV = pVV/RVT = pVV/ (RUT/MV)
where pV =Partial pressure of water vapour in the mixture
V = Volume of mixture
T = temperature
9. Specific humidity
RV = gas constant for water vapour = RU/ MV = RU/18
Mass of dry air = ma = paV/RaT = paV/ (RUT/Ma )
where pa =Partial pressure of dry air in the mixture
Ra = gas constant for dry air = RU/ Ma = RU/28.97
10. Specific humidity
specific humidity of moist air =mV/ma
= pVV/ (RUT/MV) (RUT/Ma )/ paV
=pV/paMv/Ma=pV/pa18/28.97
= 0.622pV/pa = 0.622 pV/(p-pv)
Saturated air:
The air saturated with moisture.
For saturated air, the vapor
pressure is equal to the
saturation pressure of water.
11. Relative humidity(Ø)
Ratio of the mass of water vapor actually present in the air to the mass of
water vapour that would be present if the air is saturated at the same temperature and
pressure.
Relative humidity(Ø)= pv/ps
Ø =(mvRT/V)/(mgRT/V) = mv/mg
The difference between specific
and relative humidity
12. Relative humidity(Ø)
When the air is saturated its relative
humidity is 100% .
It shows that the air can not hold
any more moisture.
When the air is purely dry, it has no
moisture content in it and the
relative humidity is 0% and partial
pressure of water vapour ( pv) is
zero.
13. Dry bulb temperature
(DBT) Tdb andSaturated vapour pressure (psat)
Dry bulb temperature is the temperature of the air measured with an ordinary
thermometer with the bulb of the thermometer open to the atmospheric air.
The bulb of the thermometer that is making the measurement has no moisture on it.
Saturated vapour pressure (psat) is the saturated partial pressure of water vapour at
the dry bulb temperature.
This is readily available in thermodynamic tables and charts.
14. Wet bulb temperature (WBT) Twb
Wet bulb temperature is the temperature measured by a thermometer whose bulb is
covered with a moistened wet wick.
When the water evaporates the temperature of the bulb is lowered. So the wet bulb
temperature depends on the moisture in the air.
When the atmospheric air is saturated with water (that is, it has 100% relative
humidity), no water can evaporate from the wet bulb.
Hence the wet bulb temperature will be same as the dry bulb temperature.
This temperature is therefore also referred to as the saturation temperature.
The difference between the dry bulb and wet bulb temperatures is known as wet bulb
depression.
Larger the wet bulb depression, lower is specific humidity of air.
15. The temperature measured is
the wet-bulb temperature
Twb and it is commonly used
in A/C applications. A simple arrangement to measure
the wet-bulb temperature.
For air–water vapor mixtures at atmospheric
pressure, Twb is approximately equal to the
adiabatic saturation temperature.
Sling psychrometer
Wet-bulb temperature measurement
Todetermine the absolute
and relative humidity of air, a
more practical approach is to
use a thermometer whose
bulb is covered with a cotton
wick saturated with water and
to blow air over the wick.
16. other•The sling psychrometer is widely used for measurements involving room air or
applications where the air velocity inside the room is small.
•The sling psychrometer consists of two thermometers mounted side by side and fitted in a
Wet-bulb temperature measurement ….
• frame with a handle for whirling the device through air.
• •The required air circulation (≈ 3 to 5 m/s) over the sensing
bulbs is obtained by whirling the psychrometer (≈ 300 RPM).
Readings are taken when both the thermometers show steady-
state readings.
• •In the aspirated psychrometer, the thermometers remain
stationary, and a small fan, blower or syringe moves the air
across the thermometer bulbs.
• •The function of the wick on the wet-bulb thermometer is to
provide a thin film of water on the sensing bulb.
17. DEW-POINT TEMPERATURE
Dew-point temperature Tdp:
The temperature at which condensation ofwater
vapour in the moist air begins when the air is
cooled at constant pressure (i.e., the saturation
temperature of water corresponding to the
vapor pressure.)
The normal thermodynamic state 1 (as shown in the
Figure) of moist air is considered as unsaturated air.
The water vapour existing at temperature T1 of the
mixture and partial pressure pv of the vapour in the
mixture is normally in a superheated state.
When the
temperature of a
cold drink is below
the dew-point
temperature of the
surrounding air, it
“sweats.”
18. Dew point temperature (DPT) Tdp
When a bottle of cool water is taken
out of the refrigerator it can be seen
that water condenses on the outside of
the bottle.
This means that the temperature of the
bottle is below the dew point
temperature of air.
When the relative humidity of the air is
100% i.e. the air is saturated, the dew
point temperature equals the wet bulb
temperature, which is also equal to
the dry bulb temperature.
20. *State 1: water vapour in the super heated
thermodynamic state - unsaturated moist air
* the water vapour exists at the dry bulb
temperature T of the mixture and partial
pressure pv more water vapour is added in
this control volume V at temperature T itself.
*The partial pressure pv will go on increasing
with the addition of water vapour until it
reaches a value ps corresponding to state 2
* after which it cannot increase further as ps is
the saturation pressure or maximum possible of
water at temperature T.
* the thermodynamic state of water vapour is
now saturated at point 2.
The air containing moisture in such a state is
called saturated air. In this state the air is holding
the maximum amount of water vapour( the
specific humidity being ωs, corresponding to the
partial pressure ps ) at temperature T of the
mixture.
Degree of saturation ()
24. Solved examplesP1. On a particular day the weather forecast states that the dry bulb temperature is 37 °C, while the
relative humidity is 50% and the barometric pressure is 101.325 kPa. Find (i) specific humidity, (ii) dew
point temperature and (iii) enthalpy of moist air on this day.
Answer:
At 37 °C the saturation pressure (ps) of water vapour is obtained from steam tables as 6.2795
kPa.
Since the relative humidity is 50%, the vapour pressure of water in air (pv) is:
pv = 0.5 x ps = 0.5 x 6.2795 = 3.13975 kPa
(i) the specific humidity or humidity ratio ω is givenby:
ω = 0.622 x pv/(pt−pv) = 0.622 x 3.13975/(101.325−3.13975) = 0.01989 kg of water/kgof
dry air
(ii) Dew point temperature Tdp (Tsat at pv = 3.13975 kPa) = 24.8 °C
(iii) The enthalpy of air (h) is given by the equation:
h = 1.005t + ω (2501+1.88t) = 1.005 x 37+0.01989 (2501+1.88 x 37) = 88.31 kJ/kg of dryair
25. P2. Will the moisture in the above air condense when it comes in contact with a cold
surface whose surface temperature is 24 °C?
Answer: Moisture will condense when it is cooled below its dew point temperature.
The dew point temperature of the air at 37 °C and 50 % relative humidity is equal to
the saturation temperature of water at a vapour pressure of 3.13975 kPa.
From steam tables, the saturation temperature of water at 3.13975 Kpa is 24.8 °C,
hence moisture in air will condense when it comes in contact with the cold surface
whose temperature, 24 °C is lower than the dew point temperature, 24.8 °C .
26. P3. Moist air at 1 atm. pressure has a dry bulb temperature of 32 °C and a wet bulb temperature
of 26 °C. Calculate a) the partial pressure of water vapour, b) humidity ratio, c) relative humidity,
d) dew point temperature, e) density of dry air in the mixture, f) density of water vapour in the
mixture and g) enthalpy of moist air using perfect gas law model and psychometric equations.
Answer:
a)Using modified Apjohn eqn. and the values of DBT,WBT and barometric pressure, the vapour
pressure is found to be:
pv = 2.956 kPa
b) The specific humidity or humidity ratio W is given by:
W = 0.622 x 2.956/(101.325-2.956) = 0.0187 kg of water/kg of dry air
c) Relative humidity RH is given by:
RH = (pv/ps) x 100 = (pv/saturation pressure at 32 °C) x 100
From steam tables, the saturation pressure of water at 32 °C is 4.7552 kPa, hence,
RH = (2.956/4.7552) x 100 = 62.16%
27. d) Dew point temperature is the saturation temperature of steam at pv=2.956 kPa.
Hence using steam tables we find that:
DPT = Tsat(2.956 kPa) = 23.8 °C
e) Density of dry air and water vapour
Applying perfect gas law to dry air:
Density of dry air ρa =(pa/RaT)=(pt−pv)/RaT = (101.325−2.956)/(287.035 x 305)x103
= 1.1236 kg/m3 of dry air
f) Similarly the density of water vapour in air is obtained using perfect gas law as:
Density of water vapour ρv = (pv/RvT) = 2.956 x 103/(461.52 x 305) = 0.021 kg/m3
28. Psychrometric Chart
All data essential for the complete thermodynamic and psychrometric analysis
of air-conditioning processes can be summarized in a psychometric chart.
At present, many forms of psychrometric charts are in use.
The chart which is most commonly used is the ω-t chart, i.e. a chart which
has specific humidity or water vapour pressure along the ordinate and the dry
bulb temperature along the abscissa.
The chart is normally constructed for a standard atmospheric pressure of
760 mm Hg or 1.01325 bar, corresponding to the pressure at the mean sea level.
29.
30. Figure: Constant Property Lines on a Psychrometric Chart
The psychrometric chart serves as a valuable aid in visualizing the
A/C processes such as heating, cooling, and humidification.
31. Today, modern air-conditioning systems can
heat, cool, humidify, dehumidify, clean, and
even deodorize the air–in other words,
condition the air to peoples’ desires.
The rate of heat generation by human body
depends on the level of the activity. For an
average adult male, it is about 87 W when
sleeping, 115 W when resting or doing office
work, and 440 W when doing heavy physical
work.
When doing light work or walking slowly, about
half of the rejected body heat is dissipated
through perspiration as latent heat while the
other half is dissipated through convection
and radiation as sensible heat.
HUMAN COMFORT AND AIR-
CONDITIONING
A body feels comfortable
when it can freely dissipate
its waste heat, and no more.
32. We cannot change the weather, but we can
change the climate in a confined space by
air-conditioning.
In an environment at 10°C with 48 km/h winds feels as cold as an
environment at -7°C with 3 km/h winds as a result of the body-chilling
effect of the air motion.
33. The comfort of the human body depends primarily on three factors:
the (dry-bulb) temperature, relative humidity, and air motion.
The relative humidity affects the amount of heat a body can dissipate through
evaporation. Most people prefer a relative humidity of 40 to 60%.
Air motion removes the warm, moist air that builds up around the body and
replaces it with fresh air.
Air motion should be strong enough to remove heat and moisture from the vicinity
of the body, but gentle enough to be unnoticed.
An important factor that affects human comfort is heat transfer by radiation
between the body and the surrounding surfaces such as walls and windows.
Other factors that affect comfort are air cleanliness, odor, and noise.
HUMAN COMFORT AND AIR-
CONDITIONING
34. AIR-CONDITIONING PROCESSES
Maintaining a living space or an industrial facility
at the desired temperature and humidity
requires some processes called air-conditioning
processes.
These processes include simple heating (raising
the temperature), simple cooling (lowering the
temperature), humidifying (adding moisture),
and dehumidifying (removing moisture).
Sometimes two or more of these processes are
needed to bring the air to a desired temperature
and humidity level.
Air is commonly heated and humidified in
winter and cooled and dehumidified in summer.
Various air-conditioning processes
35. Sensible Heating and Cooling ( = constant)• Many residential heating systems consist of a stove, a
heat pump, or an electric resistance heater.
• The air in these systems is heated by circulating it
through a duct that contains the tubing for the hot gases
or the electric resistance wires.
• Cooling can be accomplished by passing the air over
some coils through which a refrigerant or chilled water
flows.
• Addition or removal of sensible heat without change in
moisturecontent.
• Heating and cooling appear as a horizontal line since no
moisture is added to or removed from the air.
Dry air mass balance
Water mass balance
Energy balance
36. During simple cooling, specific humidity
remains constant, but relative humidity
increases and temperature decreases.
During simple heating, specific humidity
remains constant, but relative humidity
decreases and temperature increases.
37.
38.
39.
40. Heating with HumidificationProblems with the low relative humidity
resulting from sensible heating can be
eliminated by humidifying the heated air.
This is accomplished by passing the air
first through a heating section and then
through a humidifying section.
42. Cooling with Dehumidification• The specific humidity of air remains constant during a sensible cooling process, but
its relative humidity increases.
• If the relative humidity reaches undesirably high levels, it may be necessary to
remove some moisture from the air, that is, to dehumidify it.
• This requires cooling the air below its dew-point temperature to condense vapour.
43.
44.
45.
46.
47.
48.
49.
50.
51.
52.
53.
54.
55. • Air can be brought to saturation state,
adiabatically, by the evaporation of water into
the flowing air.
• As the air passes through the chamber over a long
sheet of water, the water evaporates which is
carried with the flowing stream of air, and the
specific humidity of the air increases.
• Both the air and water are cooled as the
evaporation takes place.
• This process continues until the energy
transferred from the air to the water is equal to
the energy required to vaporize the water.
• When steady conditions are reached, the air
flowing at section 2 is saturated with water
vapour.
• The temperature of the saturated air at section
2 is known as thermodynamic wet bulb
temperature or adiabatic saturation
temperature.
Adiabatic saturation process
56. Evaporative coolers lower the temperature of air using
the principle of evaporative cooling, unlike typical air
conditioning systems which use VCR and VARS.
Evaporative cooling is the addition of water vapor into
air, which causes a lowering of the temperature of the
air.
The energy needed to evaporate the water is taken from
the air in the form of sensible heat, which affects the
temperature of the air, and converted into latent heat,
the energy present in the water vapor component of the
air, whilst the air remains at a constant enthalpy value.
This conversion of sensible heat to latent heat is known
as an adiabatic process because it occurs at a constant
enthalpy value.
Evaporative cooling therefore causes a drop in the
temperature of air proportional to the sensible heat drop
and an increase in humidity proportional to the latent
heat gain.
Evaporative cooler (also swamp cooler, desert cooler and wet air cooler)