[psychrometric-basic] Psychrometric Chart for HVAC

[MarkusNeusinger]

Description

A specialized thermodynamic diagram plotting dry-bulb temperature vs humidity ratio, with overlaid curves for relative humidity, wet-bulb temperature, enthalpy, and specific volume. The fundamental tool for HVAC system design.

Key Visual Elements

• Dry-bulb temperature on x-axis
• Humidity ratio on y-axis
• Curved lines of constant relative humidity (10%-100%)
• Diagonal wet-bulb temperature lines
• Enthalpy lines (oblique)
• Saturation curve (100% RH boundary)
• Process lines showing heating, cooling, humidification paths
• Comfort zone highlighted (optional)

Applications

• HVAC engineering: designing air conditioning systems
• Building science: indoor comfort analysis
• Meteorology: air mass characterization
• Industrial drying: process optimization
• Clean room design: environmental control

Domain

Energy / Building Services / HVAC

[claude]

✅ Spec ID: psychrometric-basic

Rationale: This is a well-defined specialized thermodynamic diagram (psychrometric chart) widely used in HVAC engineering. No existing spec covers this plot type — the closest is skewt-logp-atmospheric which is a different thermodynamic diagram for meteorology. Valid and useful addition to the catalog.

[github-actions]

✅ Specification Ready: psychrometric-basic

PR: #4606

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specification.md

psychrometric-basic: Psychrometric Chart for HVAC

Description

A psychrometric chart plots dry-bulb temperature against humidity ratio, overlaid with curves for relative humidity, wet-bulb temperature, enthalpy, and specific volume. It is the fundamental tool for HVAC system design and air conditioning process analysis. The chart reveals the thermodynamic properties of moist air at a glance, enabling engineers to trace heating, cooling, humidification, and dehumidification processes as paths on the diagram.

Applications

• HVAC engineering: designing and analyzing air conditioning systems by tracing process paths (heating, cooling, mixing) on the chart
• Building science: evaluating indoor thermal comfort zones and identifying condensation risks
• Industrial process engineering: optimizing drying operations and clean room environmental control

Data

• dry_bulb_temp (float) - Dry-bulb air temperature in degrees Celsius, x-axis primary variable
• humidity_ratio (float) - Mass of water vapor per mass of dry air in g/kg, y-axis primary variable
• relative_humidity (float[]) - Constant relative humidity curves from 10% to 100% in 10% increments
• wet_bulb_temp (float[]) - Diagonal lines of constant wet-bulb temperature
• enthalpy (float[]) - Oblique lines of constant enthalpy in kJ/kg
• specific_volume (float[]) - Lines of constant specific volume in m3/kg
• Size: derived from psychrometric equations over a dry-bulb range of -10 to 50 degrees Celsius
• Example: standard atmosphere (101.325 kPa) psychrometric properties computed from ASHRAE formulas

Notes

• The saturation curve (100% RH) forms the upper boundary of the chart and should be visually prominent
• Relative humidity curves (10%-100%) should be drawn as smooth curves between the saturation line and x-axis
• Wet-bulb and enthalpy lines run diagonally from upper-left to lower-right
• Specific volume lines run at a slightly different diagonal angle
• Include at least one example HVAC process path (e.g., cooling and dehumidification) shown as an arrow or highlighted line segment between two state points
• A comfort zone region (approximately 20-26 C, 30-60% RH) should be highlighted as a shaded rectangle or polygon
• All property lines should be labeled directly on the chart, not just in a legend
• Use standard sea-level atmospheric pressure (101.325 kPa) for calculations

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Next: Add approved label to merge this specification to main.

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🤖 spec-create workflow

[github-actions]

🚀 Specification Merged!

Specification: psychrometric-basic
PR: #4606 (merged)

The specification is now in main and synced to PostgreSQL.

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Next: Add generate:{library} labels to start generating implementations.

Available libraries: matplotlib, seaborn, plotly, bokeh, altair, plotnine, pygal, highcharts, letsplot

Or use workflow dispatch for bulk operations.

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🤖 spec-create workflow