By Eamonn Ryan
Mobile refrigeration systems require reliable power sources, which can vary widely depending on the vehicle type and operational requirements. In a recent episode of Taking the Temperature on HVACR, Jamie Kitchen, with experts Jörg Saar and John Broughton, explored how power solutions differ for trucks, buses and ships. This is part three of a seven-part series.
Traditionally, compressors in mobile systems were belt-driven from the main diesel engine, with an electric clutch controlling engagement. Saar explained, “You have a belt drive onto the crankshaft of the compressor… and an electric clutch to switch it on or off.” While effective, this approach is limited by idling restrictions in many regions, which prevent engines from running continuously while stationary.
Electric buses offer a modern alternative. Compressors can draw power directly from the battery pack, eliminating the need to idle a combustion engine. “You power the compressor from the battery pack; the load of the compressor is calculated into your overall battery management,” Saar noted. This allows operators to maintain interior climate control without relying on the engine, enhancing energy efficiency and meeting environmental regulations.
Auxiliary diesel generators remain common in certain mobile applications, particularly for trucks or trailers that must maintain refrigeration while parked. These smaller engines provide just enough energy to run the refrigeration unit efficiently without powering the main drive engine.
Maritime systems present unique challenges. Large container ships often carry hundreds or thousands of reefer containers. Broughton explained, “You can hook up the reefer container to the ship’s electric system, but for longer trips, additional generators may be needed.” Ships may run multiple hundreds-of-kilowatt generators to meet both vessel and refrigeration power demands, ensuring continuous operation throughout the journey.
Powering mobile refrigeration is not just about energy supply – it is integral to maintaining the cold chain. Consistent power ensures goods remain within safe temperature ranges, preserving quality and compliance. Failures can result in financial losses, regulatory penalties and compromised product safety.
The podcast also emphasised operational planning, such as calculating load demands for battery-powered buses, integrating diesel backups for trucks, and designing shipboard power systems capable of supporting thousands of containers. These considerations highlight the complexity of mobile refrigeration beyond simple component selection, underscoring the need for comprehensive engineering expertise.