Air Heating & Cooling Psychrometric Process Calculator

Sensible Heating · Sensible Cooling · Cooling with Condensation · HVAC Process Analysis
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HVAC Air Heating & Cooling Psychrometric Calculator

This HVAC air heating and cooling calculator performs complete psychrometric process analysis for constant-pressure air systems. Instantly determine sensible heating, sensible cooling, cooling with condensation, enthalpy change (Δh), humidity ratio variation, dew point, wet-bulb temperature, and moisture removal using an interactive psychrometric chart.

Designed for HVAC engineers, mechanical engineers, students, and energy analysts, this tool evaluates heating coils, cooling coils, dehumidification systems, evaporative cooling processes, and air-conditioning performance using ASHRAE-based moist air equations.

Enter an initial air state (Tdb–RH, Tdb–Twb, Tdb–Tdew, Tdb–w, or Enthalpy–RH) and specify a final dry-bulb temperature or target humidity condition. The calculator automatically determines:

This psychrometric heating and cooling calculator is ideal for cooling coil load calculations, HVAC system design, dehumidification analysis, drying system evaluation, and energy performance assessment in air-handling units (AHUs).

Air Heating & Cooling Process Inputs

Initial State
Missing one of the required input pairs? Calculate air properties using the Psychrometric Chart Calculator →
Final State
If elevation is entered, pressure will be calculated automatically.

Heating & Cooling Process Results

Process Type — —
Total Heat / Enthalpy Change (Δh) — kJ/kg dry air
Sensible Heat (Qs) — kJ/kg dry air
Latent Heat (Ql) — kJ/kg dry air
Moisture Condensed — kg/kg dry air

State Comparison

Property Initial Final Unit
Dry Bulb Temperature — — °C
Wet Bulb Temperature — — °C
Dew Point — — °C
Relative Humidity — — %
Humidity Ratio — — kg/kg dry air
Enthalpy — — kJ/kg dry air

Need additional moist air properties such as specific volume, vapor pressure, and degree of saturation?

Use the Full Psychrometric Chart & Moist Air Properties Calculator →

Interactive Psychrometric Chart (ASHRAE Based)

Psychrometric chart showing saturation curve, relative humidity lines, enthalpy lines, specific volume lines, and wet-bulb lines. The red marker indicates the current air state.

Common Heating & Cooling Psychrometric Questions

Key Heating & Cooling Equations

Total Heat Transfer (Enthalpy Change):
Qt = Δh = h₂ − h₁

Sensible Heat (Moist Air):
Qs ≈ (1.006 + 1.86 w̄)(T₂ − T₁)   kJ/kg dry air

Latent Heat:
Ql = Qt − Qs

Humidity Ratio:
w = 0.622 Pv / (P − Pv)

Moist Air Enthalpy (SI):
h ≈ 1.006 T + w(2501 + 1.86 T)   kJ/kg dry air

Moist Air Enthalpy (IP):
h ≈ 0.24 T + w(1061 + 0.444 T)   Btu/lb dry air

Moisture Condensed:
Δw = w₁ − w₂

These relationships form the foundation of HVAC process analysis, cooling coil design, dehumidification systems, and evaporative cooling equipment.

Air Heating & Cooling Psychrometric Learning Guide

Understanding heating, cooling, condensation, and evaporation processes is essential in HVAC engineering, cooling tower design, drying systems, and air conditioning analysis. The following explanations connect psychrometric principles to real-world applications.

1. What Happens to Saturated Air When It Is Heated?

If saturated air (100% relative humidity) is heated without adding moisture, its humidity ratio remains constant, but its relative humidity decreases significantly.

This occurs because warm air can hold more water vapor. As temperature increases, the saturation humidity ratio increases, meaning the air's capacity to hold moisture becomes larger.

Result:

This principle explains why indoor air becomes dry during winter heating.

2. What Happens to Dew Point When Air Is Heated?

If air is heated without adding or removing moisture, its dew point temperature remains constant.

Dew point depends only on the actual moisture content (humidity ratio), not on dry-bulb temperature.

However, relative humidity decreases because the saturation pressure increases with temperature.

Key Insight: Heating changes relative humidity but does not change dew point unless moisture content changes.

3. What Happens When Air Is Heated While Passing Through a Stream of Water? (Cooling Tower Principle)

When warm air passes over or through water, evaporation occurs. Water evaporation absorbs latent heat from the air and surrounding liquid.

This process:

This is the core principle of cooling towers and evaporative coolers. The wet-bulb temperature becomes the limiting temperature for cooling.

Cooling towers operate by transferring heat from warm water into air through evaporation, reducing water temperature toward the ambient wet-bulb temperature.

4. How Do Hair Dryers Dry Hair?

Hair dryers accelerate evaporation by increasing air temperature and air velocity.

Heating the air:

Without heating, drying still occurs but at a slower rate because the air's moisture-holding capacity is lower.

Higher air temperature significantly reduces drying time by increasing evaporation rate.

5. How Do Air Fryers Work? (Psychrometric Perspective)

Air fryers use rapid convection of hot air to remove moisture from food surfaces.

High-temperature, low-relative-humidity air:

The drying effect combined with Maillard reactions produces the crispy texture typically associated with frying.

6. Why Do Air Conditioning Units Produce Water?

Air conditioning systems cool indoor air below its dew point temperature. When this happens, water vapor condenses on the evaporator coil.

This process:

This is an example of cooling with condensation on a psychrometric chart.

7. How Does Rain Form? (Cooling and Condensation of Rising Air)

As warm air rises in the atmosphere, it expands and cools due to lower atmospheric pressure.

When the air temperature drops to its dew point:

Further cooling leads to droplet growth and eventual precipitation (rain).

8. Additional HVAC & Engineering Insights

Keywords Related to Air Heating and Cooling

HVAC psychrometric process analysis, sensible heating calculation, cooling with condensation, humidity ratio change, evaporative cooling, cooling tower principle, dew point temperature, moist air enthalpy, dehumidification process, HVAC coil design, air drying mechanisms.