Calorie (IT) per Minute per Square Centimeter [cal(IT)/(min·cm²)]

The unit calorie (IT) per minute per square centimeter, written as cal(IT)/(min·cm²), measures heat flux density or thermal power per unit area using the International Table calorie (1 cal(IT) = 4.1868 J). It represents the amount of heat energy transferred through 1 cm² of surface every minute.

This unit is commonly used in laboratory calorimetry, solar energy experiments, and material testing where small surface areas and the calorie unit are convenient. Typical applications include:

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  Measuring solar radiation intensity on small surfaces

  
  
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  Calorimetry experiments with samples

  
  
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  Thermal testing of materials under concentrated energy flux

  
  

Mathematically, the heat flux is expressed as:

where q is heat flux in cal(IT)/(min·cm²), Q is energy in calories, A is area in cm², and t is time in minutes.

Conversion to SI units:

While SI units like W/m² are standard, cal(IT)/(min·cm²) remains convenient in small-scale experiments and historical calorimetric studies, providing an intuitive measure of energy transfer per minute per small surface area.

CHU/Hour/Square Foot

The unit CHU/hour/square foot is used to measure Cooling Heat Units per hour per square foot, commonly applied in air conditioning and refrigeration calculations. It indicates the amount of cooling energy, in CHUs, that passes through or is required for one square foot of a surface area over an hour. This measurement helps engineers and designers assess cooling loads, select appropriate air conditioning systems, and ensure thermal comfort in buildings. A higher CHU/hour/square foot value shows greater heat gain, meaning more cooling is needed, while a lower value indicates better insulation or lower cooling requirements. It is essential in designing energy-efficient HVAC systems and optimizing equipment sizing, helping reduce operational costs and maintain desired indoor temperatures. By using CHU/hour/square foot calculations, building designers can balance comfort, energy efficiency, and sustainability effectively.