Articles on psychrometrics and HVAC
Guides to psychrometrics and the Mollier diagram for HVAC engineers.
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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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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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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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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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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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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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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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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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