For other pressures, relevant corrections have to be applied. The psychrometric chart looks like a shoe. The various lines shown in the chart are as follows please refer the fig. In the first part of this series we saw representation of DB, WB, DP temperature and moisture content on the pschrometric chart.
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We shall now see how the air behaves when it is subjected to changes in temperature and humidity to suit the various applications for which the air conditioning is meant. The behavior of the air can be studied very conveniently and accurately by using a psychrometric chart.
What is Psychrometric Chart? Psychrometric charts are graphic representations of the psychrometric properties of air. By using psychrometric charts HVAC engineers can graphically analyze different types of psychrometric processes and find solution to many practical problems without having to carry out long and tedious mathematical calculations.
The psychrometric chart looks complicated with vast numbers of lines and curves in it, but is very easy to understand if you know the basic properties of air. Various Lines and Curves in the Psychrometric Chart All the properties of air indicated in the psychrometric chart are calculated at the standard atmospheric pressure. For other pressures relevant corrections have to be applied.
The psychrometric chart looks like a shoe. The various lines shown in the chart are as follows please refer the figs below : 1 Dry Bulb DB Temperature Lines: The dry bulb temperature scale is shown along the base of the shoe shaped psychrometric chart forming the sole.
The DB temperature increases from the left to the right. The vertical lines shown in the chart are the constant DB temperature lines and all the points located along a particular vertical line have same DB temperature. The moisture present within the air is indicated by the vertical scale located towards the extreme right.
The horizontal lines starting from this vertical scale are constant moisture lines. The constant WB temperature lines are the diagonal lines extending from WB temperature curved scale downwards towards the right hand side of the chart. All the points located along the constant WB temperature line have the same temperature.
The scale of the DP and WB temperature is the same, however, while the constant WB temperature lines are diagonal lines extending downwards, the constant DP temperature lines are horizontal lines. Thus the constant DP and WB temperature lines are different.
What is Psychrometric Chart? Introduction to Reading the Psychrometric Properties of Air
It is now optimized for iOS 9. Using your finger, you can easily plot HVAC and other psychrometric processes on the iPad screen while you are out in the field, save the graphs, and then email the graph and results to yourself or clients. Displays a fully customizable psychrometric chart in both landscape and portrait modes. Using your finger, you can plot as many points as you want on the screen. As you move your finger around the graph, the psychrometric properties at the top of the screen dynamically update.
It is now optimized for iOS Using your finger, you can easily plot HVAC and other psychrometric processes on the iPad screen while you are out in the field, save the graphs, and then email the graph and results to yourself or clients. Displays a fully customizable psychrometric chart in both landscape and portrait modes. Using your finger, you can plot as many points as you want on the screen. As you move your finger around the graph, the psychrometric properties at the top of the screen dynamically update. In addition, you can double-tap a point to display the point properties and then edit them. Create psychrometric processes by plotting points then connecting them with process lines.
Interactive Psychrometric Chart
Interesting Features Overview The aim of this web app is to create an interactive psychrometric chart on which you can project a range of comfort metrics as well as mapping weather data or room air conditions calculated using EnergyPlus. You can add or remove lines for a range of different metrics or highlight them individually to assist with dynamic explanations or presentations. The Psychrometric Chart The terms psychrometry and psychrometrics refer to the study of moist air and its thermodynamic properties. Whilst obviously important in the design of air-conditioning systems, these concepts are also fundamental to the understanding of many aspects of thermal comfort in buildings and the principles of climate-responsive design. The Relative Humidity Chart When developing this tool, we really wanted to be able to morph seamlessly between the standard psychrometic chart and the much simpler relative humidity chart. Having taught psychrometrics to architects in the past, we found that a major hurdle was trying to convincingly explain why the psychrometric chart uses absolute humidity in the vertical axis instead of the more familiar metric of relative humidity, and why its characteristic curved layout is so important. Now, by simply animating back and forth between the two chart types, most of that explanation becomes pretty obvious as you get to see very clearly the majority of psychrometric processes change from straight lines under the absolute humidity axis to complex curvilinear lines under relative humidity.