All the types of problems related to the psychrometric chart are covered in this video, like problems on sensible heating, sensible cooling, humidification, dehumidification and on properties of. This chart is one of the most useful tools a system designer has to describe air conditioning processes. Psychrometric chart fundamentals and its application. This chapter discusses perfect gas relations and describes their. Note that cooler air located along lower, left region of chart will not hold as much moisture as seen on the yaxis humidity ratio as warm air located along right side of chart. 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.
A9, determine a the relative humidity, the humidity ratio, and the specific enthalpy of the mixture, in kj per kg of dry air, corresponding to drybulb and wetbulb temperatures of 30 and 25c, respectively. Using the psychrometric chart problem statement the air in a oroom has a dry. Abe 201 extra practice problems extra psychrometry. Locate state point on the psychrometric chart at the intersection of 40c drybulb temperature and 20c thermodynamic wetbulb temperature lines. Sensible heat lost by the air is converted to latent heat in the added water vapor.
From the psychrometric chart, we find the adiabatic saturation temperature of the air t s 28. Gallos, the bastianblessing company introduction problems involving changes in temperature, humidity, and other properties of air can be solved by any of three methods. Just taking a look at it, you may already be confused. Introduction the aim of this section of the notes is to allow students to size. When properly used, however, it provides valuable information about the properties of air. Psychrometric properties of humid air are widely used in the analysis and modeling of thermal systems. In this work, we present a method for obtaining these properties from the multifluid mixture. If the outlet of an evaporative humidifier is saturated with water vapor. The three methods are psychrometric tables, psychrometric charts, and the psychrometric calculator. Calculates heat required to raise temperature of saturated air and determines which of two systems has the lower wet bulb temperature. It can be very helpful in troubleshooting greenhouse or livestock building environmental problems and in determining solutions. For the first stream, the point on the psychrometric chart is obtained by following the. Psychrometrics problems humidity relative humidity.
During this session, the psychrometric chart and its use in solving many air conditioning problems will be explained. The psychrometric chart properties of air at first glance, the psychrometric chart appears to be an imposing network of lines. Psychrometric charts are designed for a given atmospheric pressure. Psychrometric charts allow you to track and monitor the physical and. The course content is in a pdf file 522 kb psychrometric chart fundamentals and its application to hvac troubleshooting. For psychrometric problems, use equations to solve this problem. It provides an invaluable aid in illustrating and diagnosing environmental problems such as why heated air can hold more moisture, and conversely, how allowing moist air. Principles of food and bioprocess engineering fs 231 solutions to example problems on psychrometrics 1. We begin by identifying the conditions of the two streams on the psychrometric chart as follows. If a chart is not available for the particular atmospheric pressure desired, correction factors have to be applied to any solutions obtained from the available. What is the resulting mixed air dry bulb and wet bulb temperature.
Using the psychrometric chart, the inlet air condition shows the humidity of the drying air to be 0. Feb, 2017 psychrometry nptel, psychrometry solved questions, psychrometric chart problems, psychrometry questions,psychrometric solved questions,psychrometric chart in hindi, psychrometric problems. Introduction psychrometrics 2 the formulas that were developed were plotted on a chart that is the psychrometric chart. However, numerical cal culation is practical only if the calculation method is computerized. Psychrometric charts can be pretty tricky to interpret. Psychrometrics quiz questions hvac certification practice tests. 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. It is defined as that index which collates the com binned effects of air temperature, relative humidity and air velocity on the human body.
It consists of an inlet airwater vapor flow stream at temperature t 1, a liquid makeup. What is the final temperature of the conditioned air. Psychrometric chart fundamentals and its application to hvac troubleshooting by. Let us see what these processes are and how they are represented on the psychrometric chart. Through the dryer, the condition of the air follows a constant wetbulb line of about 27c, so at 35c its condition is a humidity of 0.
Psychrometrics is the study of the air and water vapor mixture. Principles of food and bioprocess engineering fs 231. Two and a half cubic meters of lumber is being dried at 60c dry bulb temperature and 52c wet bulb temperature. Use the psychrometric chart as a tool to determine the properties of. Sensible cooling and sensible heating are basic psychrometric processes used for various applications. Whatever the type of coil, the air stream going through it can be plotted on the psychrometric chart, and important information learned about the air stream. Solved problems in psychrometry humidity air conditioning scribd.
The psychrometric chart conveys an amazing amount of information about air. It provides an invaluable aid in illustrating and diagnosing environmental problems. It provides an invaluable aid in illustrating and diagnosing environmental problems such as why heated air can hold more moisture, and conversely, how allowing moist air to cool will result in condensation. Thus, common fluids like waterair and common pipeduct materials are used. The enthalpy can be found by using two triangles to draw a line parallel to the nearest enthalpy.
Proficiency in the use of the psychrometric chart is an important tool for designers of air conditioning systems. With so many lines and axes, you can get lost trying to follow the chart and find out which line represents which axis. The fastest and easiest method of evaluating psychrometric. Furthermore, these errors decrease with decreasing pressure. Understanding psychrometric charts helps visualization of environmental control concepts such as why heated air can hold. Understanding psychrometric charts can help you visualize environmental control concepts, such as why heated air can hold. Psychrometrics is required to properly calculate heating and cooling loads, select equipment, and design air. Alternatively the values of enthalpy for the vapor h 1 and h 2 can also be conveniently read directly from the psychrometric chart. Evaporative humidification processes normally occur without external heat transfer and are therefore adiabatic. To view the question in context, click the link above the question to open up the exam in a new tab. Psychrometric chart users manual 7 program overview the akton psychrometric chart for windows is a powerful calculation tool that can be used to perform energy and material balances for a large variety of engineering problems that involve mixtures of air and water. Psychrometric chart problems practice exam questions. Pdf algorithms for the calculation of psychrometric. We use cookies to offer you a better experience, personalize content, tailor advertising, provide social media features, and better understand the use of our services.
They are presented assuming the user to have a basic understanding of psychrometrics. The examples presented here, are for the purpose of familiarizing the user with the use of the program. Psychrometric chart fundamentals and its application to. Abe 201 extra practice problems extra psychrometry problems. The psychrometric values were based on the oncoil and offcoil drybulb and wetbulb temperatures as indicated in the diagram. Then, if possible, check your final answers using the psychrometric chart. An understanding of the shape and use of the psychrometric chart will help in diagnosing air temperature and humidity problems. Problems with the low relative humidity resulting from simple heating can be eliminated by. Uses of psychrometric chart the psychrometric chart conveys an amazing amount of information about air. Psychrometrics is the study of the thermodynamic properties of moist air. So why is it important to know how to read a psychrometric chart. Sample mechanical pe exam question on psychrometrics.
Psychrometric processes 1521 mechanical engineering me462562 sustainable energy. A simple adiabatic saturator is shown in figure 12. Solved problems in psychrometry free download as word doc. Using the psychrometric chart university of alabama. Pdf basic process calculations and simulations in drying. A psychrometric chart presents physical and thermal properties of moist air in a graphical form. Solved problems in psychrometry humidity air conditioning. Properties properties of each inlet stream are determined from the psychrometric chart fig. It can be very helpful in troubleshooting and finding solutions to greenhouse or livestock building environmental problems. Basic relationships most of the psychrometric equations that are used in practice are based on the premise that air is. The solution to the problem is shown below to help the reader better understand the problem before it is solved in ees. Psychrometric chart fundamentals and its application to hvac. Reading and interpreting a psychrometric chart sunbird dcim.
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