Articles on Psychrometrics and HVAC
Guides to psychrometrics and the psychrometric chart for HVAC engineers, in IP units.
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Cooling Coil in an AHU: Capacity and Dehumidification Calculation
How to size a cooling coil in an air handling unit. Calculating cooling capacity, dehumidification, dew point and the air state after the coil.
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Energy Recovery (ERV/HRV): Efficiency, Savings, Air States
How to calculate energy recovery savings in HVAC: temperature effectiveness, air states on the psychrometric chart, plate vs. wheel, and standards.
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Cleanroom Air: Psychrometric Temperature and Humidity Requirements
Psychrometric requirements for cleanrooms per ISO 14644 and cGMP: the effect of humidity on ESD and microbial contamination, and HVAC design.
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Condensation in Buildings: Causes, Calculation and Prevention
When and where water vapor condensation occurs, surface vs. interstitial condensation, and how to predict it from the dew point and the chart.
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Data Centers and Air Humidity: Psychrometrics for IT Infrastructure
Data center psychrometrics: ESD and corrosion risks, ASHRAE classes A1–A4, free cooling and adiabatic cooling. How to optimize total energy use.
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Industrial Drying and Psychrometrics: Dryer Design on the Chart
Psychrometrics in industrial drying: the drying phases, energy balance, recirculation and a lumber-kiln example. Calculations on the psychrometric chart.
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Meteorological Psychrometrics: Atmospheric Humidity and Its Uses
Psychrometrics in meteorology: the condensation level, adiabatic lapse rate, chinook winds and fog. EPW and TMY3 data for building energy simulation.
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Psychrometrics in Agriculture: Greenhouses, Grain and Crop Drying
Psychrometrics in agriculture: greenhouse VPD, grain equilibrium moisture (EMC) and post-harvest corn drying. Calculations on the psychrometric chart.
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Air Conditioning Design on the Psychrometric Chart: Step by Step
Designing air conditioning with the psychrometric chart: design conditions, air mixing and cooling capacity. A worked example of an office for 100 people.
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Air Humidification in HVAC: Steam, Adiabatic or Ultrasonic?
Comparing humidification options in HVAC — steam, adiabatic, ultrasonic. Capacity calculation, hygiene and how each appears on the psychrometric chart.
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Air Humidity Calculation: All the Psychrometric Formulas
A full reference of psychrometric equations: saturation vapor pressure (Buck, Magnus), humidity ratio, enthalpy, dew point and density. With examples.
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Dew Point Calculation: Formulas, Tables, Online Calculator
How to calculate dew point from dry-bulb temperature and relative humidity. Magnus–Tetens, ASHRAE comparison, and worked examples in IP units.
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Desiccant Dehumidification: Silica Gel, Zeolites and Desiccant Wheels
Desiccant dehumidification with silica gel and desiccant wheels: the principle, the psychrometric chart and uses in industry, pharma and storage.
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Evaporative Cooling: Principle, Efficiency, Psychrometric Chart
How evaporative (adiabatic) cooling works, calculating saturation efficiency and plotting it on the psychrometric chart. Direct vs. indirect cooling.
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Calculating Moist Air Enthalpy: Formula, Tables, Psychrometric Chart
How to calculate moist air enthalpy from temperature and humidity. ASHRAE IP formula plus worked examples of heating and cooling coil capacity.
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The Psychrometric Chart: A Complete Guide for HVAC Engineers
Learn to read the psychrometric chart, plot air-treatment processes and export the result to your submittal. Calculations per ASHRAE Fundamentals 2021.
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Moist Air Processes: Heat, Cool, Humidify, Dry
Heating, cooling, humidification and drying on the psychrometric chart — the four basic processes with examples and capacity calculations.
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Relative Humidity: What It Is, Why It Shifts, How to Measure It
What relative humidity is, why it changes with temperature, and how to measure it. Recommended levels for homes, museums and data centers.
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Thermal Comfort and the PMV/PPD Index: Calculation per ISO 7730
What the PMV and PPD indices are, how thermal comfort is calculated and the role of air humidity. Standards ASHRAE 55 and ISO 7730.
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Wet-Bulb Temperature: Physics, Measurement, and the Psychrometric Chart
What wet-bulb temperature is, how a psychrometer measures it and where to find it on the psychrometric chart. Dew point difference and Sprung equation.
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What Is Psychrometrics? A Guide to the Science of Moist Air
Psychrometrics made clear: humidity ratio, enthalpy, dew point and the psychrometric chart. Practical uses in HVAC, drying and building science.
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