Air Temperature Rise Calculator

Temperature Rise Formula:

\[ \Delta T = \frac{Q}{\dot{m} \times c_{air}} \]

Temperature Rise (ΔT): °F

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1. What is an Air Temperature Rise Calculator?

Definition: This calculator determines the temperature increase of air when heat is added, based on heat input, mass flow rate, and air's specific heat capacity.

Purpose: It helps HVAC engineers and technicians understand how much air temperature will rise when heat is added to an airflow stream.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ \Delta T = \frac{Q}{\dot{m} \times c_{air}} \]

Where:

\( \Delta T \) — Temperature rise (°F)
\( Q \) — Heat input (BTU/h)
\( \dot{m} \) — Mass flow rate (lb/h)
\( c_{air} \) — Specific heat of air (BTU/lb·°F, default 0.24)

Explanation: The heat input is divided by the product of mass flow rate and specific heat to determine temperature increase.

3. Importance of Temperature Rise Calculation

Details: Accurate temperature rise calculations are crucial for proper HVAC system design, heat exchanger performance, and ventilation requirements.

4. Using the Calculator

Tips: Enter the heat input in BTU/h, mass flow rate in lb/h, and specific heat (default 0.24 BTU/lb·°F for dry air). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: How do I convert CFM to lb/h for airflow?
A: Multiply CFM by 4.5 (for standard air at 70°F and sea level) to get lb/h.

Q2: What's the specific heat of moist air?
A: It's slightly higher than dry air - typically about 0.25 BTU/lb·°F for average humidity.

Q3: Why is temperature rise important in HVAC?
A: It helps determine heating capacity needs and ensures proper air distribution.

Q4: How does altitude affect the calculation?
A: At higher altitudes, air density decreases, requiring adjustments to mass flow rate.

Q5: Can this be used for other gases?
A: Yes, but you must use the correct specific heat value for the particular gas.