Articles on psychrometrics and HVAC
Guides to psychrometrics and the Mollier diagram for HVAC engineers.
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Cooling coil in an AHU: capacity and dehumidification calculation
How to design a cooling coil in an air handling unit. Calculating the cooling capacity, dehumidification, dew point and the air state after the coil.
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Heat recovery (HRV): efficiency, energy savings, air states
How to calculate HRV energy savings in HVAC: temperature efficiency, air states in the h-x diagram, plate vs. rotary exchanger, and standards.
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Cleanroom air: psychrometric temperature and humidity requirements
Psychrometric requirements for cleanrooms per ISO 14644 and EU GMP: the effect of humidity on ESD and microbial contamination, and HVAC design.
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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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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 h-x diagram.
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Industrial drying and psychrometrics: dryer design on the h-x diagram
Psychrometrics in industrial drying: the drying phases, energy balance, recirculation and a wood-dryer example. Calculations on the h-x diagram.
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Meteorological psychrometrics: atmospheric humidity and its uses
Psychrometrics in meteorology: the condensation level, adiabatic lapse rate, the föhn effect and fog. EPW climate 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 h-x diagram.
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Air conditioning design on the h-x diagram: a step-by-step guide
Designing air conditioning with the h-x diagram: 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 air humidification options in HVAC — steam, adiabatic, ultrasonic. Capacity calculation, hygiene and how each appears on the h-x diagram.
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Air humidity calculation: all the psychrometric formulas explained
A full reference of psychrometric equations: saturation vapor pressure (Buck, Magnus), humidity ratio, enthalpy, dew point and density. With examples.
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Desiccant dehumidification: silica gel, zeolites and desiccant rotors
Desiccant dehumidification with silica gel and rotary dehumidifiers: the principle, the h-x diagram and uses in industry, pharma and storage.
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Dew point calculation: formulas, tables, online calculator
How to calculate the dew point from temperature and relative humidity. Magnus–Tetens equation, ASHRAE comparison, and examples for HVAC engineers.
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Evaporative cooling: principle, efficiency and the h-x diagram
How evaporative (adiabatic) cooling works, calculating the saturation efficiency and plotting it on the h-x diagram. Direct vs. indirect cooling.
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Moist air processes on the h-x diagram: heat, cool, humidify, dry
Heating, cooling, humidification and drying on the h-x diagram — the four basic psychrometric processes with examples and capacity calculations.
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Calculating moist air enthalpy: formula, tables and h-x diagram
How to calculate the enthalpy of moist air from temperature and humidity. ASHRAE formula plus worked examples of heating and cooling coil capacity.
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The Mollier (h-x) diagram: a complete guide for HVAC engineers
Learn to read the Mollier h-x diagram, plot air-treatment processes and export the result to your report. Calculations per ASHRAE Fundamentals 2021.
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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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What is psychrometrics? A guide to the science of moist air
Psychrometrics made clear: humidity ratio, enthalpy, dew point and the h-x diagram. Practical uses in HVAC, drying and building physics.
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Wet-bulb temperature: physics, measurement, and the h-x diagram
What wet-bulb temperature is, how a psychrometer measures it and where to find it on the h-x diagram. Difference from dew point and the Sprung equation.
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