Led by Jason Long and Jacob Wolfe with M&M Carnot, focuses on the use of CO2 as a natural refrigerant and the potential benefits of free cooling for HVAC systems. The session emphasizes the increasing need to adopt environmentally friendly refrigerants and more energy-efficient cooling technologies due to the upcoming phase-out of synthetic refrigerants like R134a and R410A.
Jacob begins by discussing the three operational modes of CO2 cooling systems: transcritical, subcritical (condensing), and free cooling. The transcritical mode is the least efficient, occurring when the outdoor temperature is above 88°F. In this mode, the system cools gas, and any flash gas is re-cooled through a gas cooler. Adiabatic gas coolers can reduce transcritical operation, improving efficiency. The subcritical mode occurs when the temperature is below 88°F, where the system operates more efficiently than traditional synthetic refrigerant systems by condensing refrigerant.
The most energy-efficient mode is free cooling, which occurs at low outdoor temperatures. In this mode, the system can operate without mechanical compression by using thermosiphon or refrigerant migration, relying on gravity to circulate the CO2. This reduces energy consumption and operational costs significantly. This feature is particularly useful in climates with cooler outdoor temperatures, such as Denver, where free cooling can be utilized for a significant portion of the year.
The presentation also covers different CO2 product offerings, including crack perimeter units and in-row cooling systems with capacities ranging from 15 to 75 tons. These systems offer energy savings through free cooling and provide a more environmentally sustainable solution by using CO2, which has a global warming potential (GWP) of just 1. This makes it immune to future phase-out regulations.
Jacob highlights the benefits of using CO2 as a refrigerant, such as its high-pressure differential, which allows for more efficient heat transfer and smaller system footprints. He also emphasizes that CO2 systems are safe, with non-toxic and non-flammable properties, and do not require additional safety measures beyond those needed for synthetic refrigerants. Additionally, CO2 systems can achieve longer vertical pipe runs, making them suitable for various installation environments.
The webinar concludes by discussing the advantages of CO2 systems over synthetic refrigerants, including better energy efficiency, lower operational costs, and the avoidance of future regulatory restrictions. Despite CO2 systems being about 1.5 times more expensive than traditional systems, their long-term savings, particularly in energy costs and heat recovery, make them a viable and attractive option for environmentally conscious building managers.
In summary, the use of natural refrigerants like CO2 and free cooling technology provides an energy-efficient and sustainable alternative for HVAC systems. As synthetic refrigerants are phased out, CO2-based systems offer a future-proof solution that helps reduce carbon footprints while maintaining high performance in various building applications.
