HDEvapCooler application icon HDEvapCooler Evaporative Cooler Sizing & Performance Calculator

HDEvapCooler is a desktop tool for sizing and analyzing direct evaporative coolers used in commercial and industrial HVAC systems. Whether you are selecting a new unit, verifying an existing installation, or optimizing media depth for a target efficiency, HDEvapCooler allows you to calculate the correct results.

HDEvapCooler supports three calculation modes, letting you work from whatever parameters are already known:

  • Size Mode — enter the cooler media height and width and HDEvapCooler calculates the face velocity and resulting efficiency from its built-in media curves.
  • Efficiency Mode — specify a target saturation efficiency and HDEvapCooler back-calculates the required media area and selects an appropriate model size.
  • Leaving Dry Bulb Mode — enter the desired supply-air temperature and HDEvapCooler derives the implied efficiency and sizes the media accordingly.

In all modes the psychrometric state of the leaving air is fully resolved and the program reports energy transfer, water consumption, air pressure drop, overall equipment dimensions, and shipping weight.

KEY FEATURES

  1. Three calculation modes — Size, Efficiency, and Leaving Dry Bulb — cover every common design scenario without manual iteration.
  2. Built-in media efficiency curves for five standard media thicknesses: 4, 6, 8, 12, and 16 inches (10, 15, 20, 30, and 40 cm in SI mode); efficiency is calculated from empirical polynomial fits, not generic assumptions.
  3. Full IP and SI unit support — toggle between cfm/F/in. and l/s/C/cm with a single click; input values are automatically converted and results are reported in the selected unit system.
  4. Complete psychrometric analysis of entering and leaving air states — humidity ratio, specific volume, density, and enthalpy — with total, sensible, and latent energy transfer reported separately.
  5. Air pressure drop calculated from calibrated media resistance curves for each thickness, reported in inches (or cm) of water column.
  6. Water system sizing — evaporation rate (volume and mass), recirculating water flow rate, and minimum pump size are computed automatically.
  7. Equipment sizing — overall cooler height and width (media plus frame allowance) and tabulated dry and wet shipping weights for a wide range of unit sizes.
  8. Auto-generated EC model number (e.g., EC-72x60x8) identifies the selected unit for specifications and submittals.
  9. PDF report generation — produces a cleanly formatted summary of input conditions and all calculation results, ready to attach to any project submittal.
  10. Clipboard copy — exports all inputs and results as tab-delimited text for pasting directly into spreadsheets or project reports.
HDEvapCooler main form showing input conditions and calculation results

CALCULATION RESULTS

For every set of inputs, HDEvapCooler reports the following output values in the selected unit system:

  • Model — auto-generated EC model number (Height × Width × Thickness)
  • Media Area — active face area of the evaporative media (sq.ft. / sq.m)
  • Face Velocity — air velocity through the media (fpm / m/s)
  • Efficiency — saturation effectiveness of the media (%)
  • Total Energy — total cooling capacity (Btu/hr / W)
  • Sensible Energy — sensible cooling component (Btu/hr / W)
  • Latent Energy — latent (evaporative) component (Btu/hr / W)
  • Leaving Air Dry Bulb — supply-air dry-bulb temperature (°F / °C)
  • Leaving Air Wet Bulb — supply-air wet-bulb temperature (°F / °C)
  • Air Pressure Drop — static resistance across the media (in. WC / cm WC)
  • Evaporation Rate — volume of water evaporated per hour (gph / l/h)
  • Evaporation Mass — mass of water evaporated per hour (lb/hr / kg/hr)
  • Water Flow — recirculating water flow rate (gpm / l/m)
  • Pump Size — minimum recirculating pump capacity (hp / W)
  • Overall Height — total unit height including frame (in. / cm)
  • Overall Width — total unit width including frame (in. / cm)
  • Weight – Dry — shipping weight, empty (lbs. / kg)
  • Weight – Wet — operating weight with water (lbs. / kg)

MEDIA THICKNESS OPTIONS

HDEvapCooler covers the five standard cellulose media depths used in commercial evaporative coolers. Each thickness has its own set of empirically derived efficiency and pressure-drop curves, so results reflect the actual performance of that specific media type rather than a generic approximation. Thicker media achieves higher saturation effectiveness at a given face velocity but also carries greater air-side resistance — HDEvapCooler quantifies both so the engineer can make a fully informed selection.

View more app screenshots here.

System Requirements

  • Windows 10 or Windows 11
  • .NET 8 Runtime (included in installer)
  • 50 MB disk space
  • Standalone or integrated with HDPsyChart

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