Calculating CFM & Tons of Refrigeration | Getting Back to Basics!

In this podcast episode, we get back to basics and show you how to calculate CFM and tons of refrigeration.

Here is what you will learn.

Section 1 Air Mixing. Mixing air on the psychrometric chart.

Section 2 Calculating SHR. The sensible heat ratio is one of the most important HVAC aspects of the psych chart.

Section 3 Calculating CFM utilizing the sensible heat equation.

Section 4 Calculating tons of refrigeration using enthalpy and the total cooling equation.

Bonus section: Why systems fail at part load.

You can watch the full video version of this podcast on our YouTube Channel: ⁠⁠⁠⁠⁠https://www.youtube.com/@HVAC-TV⁠⁠⁠⁠⁠

The Engineers HVAC Podcast: ⁠⁠⁠⁠⁠https://anchor.fm/engineers-hvac-podcast⁠⁠⁠⁠⁠

Insight Partners (Commercial HVAC Products in NC, SC, GA): Website: ⁠⁠⁠⁠www.insightusa.com⁠⁠⁠⁠⁠

Hobbs & Associates, Inc. (Commercial HVAC Products in VA, TN, MD, AL): ⁠⁠⁠⁠⁠www.hobbsassociates.com⁠

Designing systems for full load is easy, but part load is not so much. Understanding the Sensible Heat Ratio, the Sensible Heat Equation, and the Total Cooling Equation is fundamental to understanding what happens at part load.

To get the most out of this class and follow along, you can print out a copy of our Psych Chart here: https://www.insightusa.com/psychcharts

The sensible heat ratio (SHR) is a term used in heating, ventilation, and air conditioning (HVAC) design to describe the ratio of sensible heat to total heat (sensible plus latent heat) in the air. It is an important parameter to consider when designing HVAC systems because it helps engineers and designers understand the thermal characteristics of the air and make informed decisions about system capacity and performance.

In HVAC design, the SHR is essential for several reasons:

Equipment Sizing: The SHR helps determine the appropriate capacity of heating and cooling equipment. Air conditioning systems should be sized to provide the necessary sensible cooling (temperature control) and latent cooling (humidity control). A higher SHR indicates a greater need for sensible cooling.

Comfort Control: Knowing the SHR helps HVAC designers create indoor environments that are comfortable and meet occupant requirements. For example, in a dry climate with a low SHR, more emphasis may be placed on sensible cooling to maintain a comfortable temperature.

Energy Efficiency: Understanding the SHR can help optimize HVAC system performance. By designing systems with the right balance of sensible and latent cooling, energy consumption can be minimized, leading to cost savings.

Dehumidification: In areas with high humidity levels, it's crucial to consider the latent cooling capacity of the HVAC system to effectively remove moisture from the air and prevent issues like mold growth and discomfort.

In summary, the sensible heat ratio (SHR) is a key parameter in HVAC design that helps determine the balance between sensible and latent heat in the air. It guides equipment sizing, energy efficiency considerations, and comfort control strategies to ensure effective temperature and humidity control in indoor spaces. Different regions and applications may require different SHR values, making it an important factor to consider when designing HVAC systems.