Psychrometric chart problems practice exam questions. Important psychrometric processes namely, sensible cooling and heating, cooling. Pdf analysis of airconditioning and drying processes. Other modules build on the information from this module to explain the psychrometrics of various air conditioning.
Use of psychrometric analysis is also important to determine the volume flow rates of air to be pushed into the ducting system and the sizing of the major system components. If the dry bulb remains constant, the process involves the addition of latent heat only. Psychrometric processes 621 mechanical engineering me462562 sustainable energy. Pdf analysis of airconditioning and drying processes using. Solution manual for basic principles and calculations in. The psychrometric chart properties of air at first glance, the psychrometric chart appears to be an imposing network of lines. Riggs goes far beyond traditional introductory chemical engineering topics, presenting applications that reflect the full scope of contemporary chemical, petroleum, and environmental engineering. Exergetic efficiency assessment of key psychrometric processes vishal h. The line representing saturated air where the relative humidity rh is 100% is the uppermost curved line in the chart. Email a list of all the points and their properties for a completed chart, along with a pdf of the chart itself. Psychrometric chart fundamentals and its application to. The basics of hvac hvac for beginners bright hub engineering.
Create an unlimited number of psychrometric chart projects. The process of adiabatic humidification is represented on psychrometric chart in fig. Psychrometric chart fundamentals and its application to hvac troubleshooting by. Basic principles and calculations in chemical engineering, eighth edition goes far beyond traditional introductory chemical engineering topics, presenting applications that reflect the full scope of contemporary chemical, petroleum, and environmental engineering.
The analysis of psychrometric processes is performed by considering a. These processes include simple heating raising the temperature, simple cooling lowering the temperature. Sensible heat lost by the air is converted to latent heat in the added water vapor. During this session, the psychrometric chart and its use in solving many air conditioning problems will be explained. Celebrating its fiftieth anniversary as the fields leading practical introduction, it has. Smaller charts are used in most of the subsequent examples. Sensible heating or cooling a psychrometric process that. Let us see what these processes are and how they are represented on the psychrometric chart. Free download basic principles and calculations in chemical engineering by david m. The cooling processes on psychrometric chart the cooling processes in psychrometric chart are illustrated below.
Riggs goes far beyond traditional introductory chemical engineering topics, presenting applications that reflect the full scope of contemporary chemical, petroleum, and. Governing equations following the works of 10, 11, 12, the basic psychrometric. Psychrometric chart identify parts of the chart determine moist air properties use chart to analyze processes involving moist air. Hvac stands for heating, ventilation, and air conditioning and is a complex branch of engineering. Process calculations this posts provides detailed resources for basic principles and calculations in chemical engineering book 8th edition by david m. Sep 29, 2014 psychrometric processes or air conditioning processes 1. Knowledge of psychrometric properties is the basic requirement for environmental measurements and drying processes. Create psychrometric processes by plotting points then connecting them with process lines. Sensible cooling and sensible heating of air psychrometric processes in the domestic and industrial air conditioning applications some psychrometric processes have to be performed on the air to change the psychrometric properties of air so as to obtain certain values of. Airconditioning processes are usually shown on a psychrometric chart, which was developed in the early 1900s by german engineer richard mollier. Familiarise you with load calculation and duct design.
Psychrometric analysis and air conditioning cycles. Some of the common psychrometric processes carried out on air are. Blackburn, pe, mba course content introduction if hvac problems and challenges are to be properly diagnosed and designed, it is essential that the psychrometric chart and psychrometrics in general be clearly understood. Psychrometric processes unm mechanical engineering program. As the air flows, it may be cooled or heated, humidified or dehumidified, or simply adiabatically saturated, depending on the mean surface temperature of the water. Sensible cooling in sensible cooling process, the temperature of air changes from a point a to point c, maintaining constant humidity ratio. The moisture holding capacity of air increases dramatically with temperature. Psychrometric chart an overview sciencedirect topics. Basic principles and calculations in chemical engineering. The cpd articles in the april and august editions of the cibse journal have considered the main properties of moist air that may be determined from a pair of coincident properties using the psychrometric chart and how values may be calculated in the absence of a. In this article we learn hvac for beginners along with the processes of air conditioning, comfort zone within a psychometric chart and a discussion about the need for comfort air engineering. To view the question in context, click the link above the question to open up the exam in a new tab.
It follows a constant humidity ratio line on the psychrometric chart. This is the basic constant volume, variable temperature approach. Humidification the section on typical air conditioning processes shows winter and summer schematic diagrams and psychrometric charts. Psychrometrics can be used to predict changes in the environment when the amount of heat andor moisture in the air changes. The basic psychrometric processes the cpd articles in the april and august editions of the cibse journal have considered the main properties of moist air that may be determined from a pair of coincident properties using the psychrometric chart and how values may be calculated in the absence of a chart.
Psychrometric processes or air conditioning processes 1. When considering whole processes on a standard cibse psychrometric chart particularly when considering summer cycles the individual process lines can be. Indicate an example of a sensible heating process on a. Analysis of airconditioning and drying processes using. Exergetic efficiency assessment of key psychrometric. Feb, 2017 psychrometry nptel, psychrometry solved questions, psychrometric chart problems, psychrometry questions, psychrometric solved questions, psychrometric chart. When the drybulb, wetbulb, and dewpo int temperatures are the same, the air is saturated.
The various psychrometric processes involved in air conditioning to vary the. Psychrometric chart and use this to estimate the heater duty. Celebrating its fiftieth anniversary as the fields leading practical. Psychrometric chart fundamentals engineering manual of automatic control 40 the abridged psychrometric chart figure 2 is an abridged form of chart no. When properly used, however, it provides valuable information about the properties of air. It is intended to give introductory terminology to what we will discuss and explore through this course. To provide thermal comfort conditioning in occupied spaces, air must be conditioned.
Basic principles and calculations in chemical engineering 8th edition author. Figure 3 shows a portion of a mathcad file where students are asked to define basic psychrometric functions that are used in the air conditioning analysis. A process report can be generated summarizing the process by choosing the data process report menu option from the data pick on the main menu. The humidifying process adds moisture to the air and crosses constant moisture lines. Analysis of air conditioning processes introduction moist air is a mixture of dry air gases such as o 2, n 2, co 2, etc and water vapour. However, perfect gas relations can be used instead of these formulas in most airconditioning problems. These analysis include summer air conditioning cycle and winter air conditioning cycle which may cover the four basic combined processes discussed previously. Download basic principles and calculations in chemical engineering by david m. Analysis of the degrees of freedom in steadystate processes chapter. This tutorial is meant to focus on the most basic elements of program operation. The third property, dewpoint temperature, is the temperature at which moisture leaves the air and condenses on objects, just as dew forms on grass and plant leaves. Basic processes in ac latent heat process air washer in an air washer, air leaves through a spray of water as shown in fig.
Humidity psychrometric charts and their use part v. Dec 16, 2015 the humidifying process adds moisture to the air and crosses constant moisture lines. The process of sensible heating is represented on the psychrometric chart by straight. A useful tool for studying and analyzing thermodynamics properties of moist air is the psychrometric chart. Basic psychrometric processes are heat i ng, cooling, adiabatic humidification and air mixing, which can be combined according to different applications or equipment leal et al. Starting with the original authors suggested thought process for analyzing typical problems, the reader is then exposed to a buzzword of our time. Up until a few years ago the psych chart could still be justified as a device that allows you to visualize the process. The properties that are displayed on the report, and the order in which they appear can also be selected from the report box in the psychrometric property dialog box. Psychrometric processes for heating and air conditioning. To cover the basic principle of psychrometric and applied psychrometric. The relative humidity lines in the psychrometric chart are curved lines that move upwards to the right. Understand the concept of vapour compression refrigeration system and other cooling. Any question displayed here that is a follow on question may require information from a previous question.
Though air washer is a and extremely useful simple device, it is not. The temperature can be measured by an ordinary thermometer which gives the drybulb temperature, or by a thermometer when a water film is evaporating off the bulb which gives the wet bulb temperature. There are four basic processes for summer and winter air conditioning systems. Use of psychrometric analysis is also important to determine the volume flow rates of air to be pushed into the ducting system and the. This module also explains how to plot the eight basic air conditioning processes on the chart. Psychrometrics is the study of the air and water vapor mixture. When two air streams having different psychrometric property are mixed together, the quality of resultant air can be obtained by taking heat and moisture balance.
Sensible cooling and sensible heating are basic psychrometric processes used for various applications. The values of volume lines are generally given at the base of the chart. Analysis of airconditioning and drying processes using spreadsheet addin for psychrometric data. Kapadia2 1 pg student, thermal engineering 2principal 1, 2 svmit, bharuch392001, gujarat, india abstract the study focused on finding exergy efficiencies for basic psychometric processes, such as. Psychrometric processes 1521 mechanical engineering me462562 sustainable energy.
By working through the tutorial instructions, you should have an understanding of the basic program elements and how they work together. The sensible cooling of air is the process in which only the sensible heat of the air is removed so as to reduce its temperature, and there is no change in the moisture content kgkg of dry air of. Some of the scale lines have been removed to simplify illustrations of the psychrometric processes. This first task allows students to gain an understanding of the basic psychrometric processes by creating specific functions in mathcadexcel. Psychrometrics is required to properly calculate heating and cooling loads, select equipment, and design air distribution systems. Very accurate values of psychrometric properties are available through smart phone apps, computer programs and online calculators. Proficiency in the use of the psychrometric chart is an important tool for designers of air conditioning systems. Familiarise you with the refrigerants, vapour compression refrigeration system and multi stage vapour compression system. But new graphical psychrometric software does that too and very accurately. The following definitions of the psychrometric processes are described in every day vernacular that will be referenced further on. Sensible cooling and sensible heating of air psychrometric processes in the domestic and industrial air conditioning applications some psychrometric processes have to be performed on the air to change the psychrometric properties of air so as to obtain certain values of temperature and humidity of air. Relative humidity is the ratio of the amount of moisture in the air to the maximum amount of moisture the air can hold at the same temperature and pressure. Psychrometric chart fundamentals and its application to hvac.
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