The webinar, hosted by Cody Dorris and presented by Bob Sandberg from InTest Thermal, focused on the benefits and applications of using liquid nitrogen (LN2) for cooling in various industries.
Bob presented on the benefits and applications of LN2 (liquid nitrogen) cooling. He explained that LN2's extremely low evaporation temperature of 196°C and high heat absorption capacity make it significantly more effective than other refrigerants like R508B, LCO2, and R448A for achieving rapid cooling to temperatures below -80°C. Bob demonstrated through practical examples that LN2 systems can cool a 90-liter thermal chamber 14 times faster than mechanical refrigeration systems to reach -60°C, and 16 times faster to reach -80°C, while also requiring significantly less physical footprint and electrical power compared to traditional chillers. He discussed practical examples demonstrating LN2's faster cooling rates and smaller footprint compared to mechanical refrigeration systems.
Bob explained that N2 exhaust can be recycled but must be carefully managed to avoid creating back pressure that could limit liquid nitrogen flow to the cooling target. He detailed various LN2 systems including direct injection control systems, thermal plates, and thermal chambers, noting that thermal plates can achieve temperature changes of 50°C per minute and operate within a range of -100°C to +200°C. Bob also discussed facility requirements for LN2 systems, explaining that consumption varies significantly depending on the system type, with thermal plates using approximately 60 pounds per hour compared to 737 pounds per hour for an LN2 chiller, which affects the size of storage tanks needed.
Cody asked Bob about LN2 usage patterns, specifically whether consumption doubles when heat load doubles and if it remains linear during temperature transitions. Bob explained that LN2 consumption is not perfectly linear due to system losses, but it does decrease significantly once the target temperature of minus 100°C is reached, from 60 pounds per hour during ramping to around 5 pounds per hour at steady state. Bob also discussed safety considerations for LN2 systems, including the need for proper exhaust ventilation and oxygen sensors to prevent oxygen depletion, as well as recommended safety precautions like using cryogenic gloves and goggles.
Bob presented on the safe use of liquid nitrogen (LN2), explaining key safety considerations including pressure management and temperature limitations to prevent liquid oxygen formation. He discussed various LN2 systems available including thermal plates, chambers, and fluid chillers, and addressed questions from Cody about equipment connections, gaseous nitrogen purging, chamber sizes, and lead times. Cody confirmed that chamber sizes range from 10 liters to 765 liters with typical lead times of 10-12 weeks and noted that while thermal streams currently don't use LN2, custom LN2-based thermal stream solutions are available.
The Q&A session touched on topics like LN2 usage linearity, system connections, and the use of gaseous nitrogen for purging.