Question

In a psychrometric process, the sensible heat added is 30 kJ/s and the latent heat added is 20 kJ/s. The sensible heat factor for the process will be:

• A. 0.60
• B. 0.67
• C. 1.50
• D. 1.67

Hint:

The SHF can never be greater than 1.0. If your calculation results in a number like 1.50 or 1.67, it usually means you accidentally placed the total heat in the numerator instead of the sensible heat.

Answer 1

The Correct Option is A

1. Identifying the Components:

• Sensible Heat (SH): This is the heat that causes a change in the dry-bulb temperature of the air without changing its moisture content. Given as 30 kJ/s.

• Latent Heat (LH): This is the heat that causes a change in the moisture content (humidity) of the air without changing its dry-bulb temperature. Given as 20 kJ/s.

2. Calculating Total Heat (TH): The total heat added to the system is the arithmetic sum of the sensible and latent heat components: $$\text{Total Heat (TH)} = \text{SH} + \text{LH}$$ $$\text{TH} = 30 + 20 = 50 \text{ kJ/s}$$

3. Applying the SHF Formula: The Sensible Heat Factor is defined by the following ratio: $$\text{SHF} = \frac{\text{Sensible Heat}}{\text{Total Heat}} = \frac{\text{SH}}{\text{SH} + \text{LH}}\lt strong\gt 4. Final Calculation:\lt /strong\gt \text{SHF} = \frac{30}{30 + 20} = \frac{30}{50}$$ $$\text{SHF} = 0.60$$ A Sensible Heat Factor of 0.60 indicates that 60% of the total heating load is being used to raise the temperature of the air, while the remaining 40% is being used to increase its humidity.