By Eamonn Ryan
Refrigeration and air conditioning are vital for both commercial and industrial applications, ensuring that perishable goods are preserved and indoor environments remain comfortable. On a recent episode of Taking the Temperature on HVACR, host Jamie Kitchen brought together Jörg Saar and John Broughton, two leading experts in the field, to discuss the distinctions and interconnections between stationary and mobile refrigeration systems. This is part one of a seven-part series.
Kitchen opened the discussion by highlighting the commonality of stationary systems: “You go to your supermarket, you have your house in air conditioning, you have your hotel or mall – all of these have what you would call stationary systems.” Stationary systems are generally fixed installations designed for consistent environments, such as supermarkets, hotels, office buildings or industrial cold rooms. These systems are engineered to maintain a constant temperature over long periods, with little concern for vibration or extreme environmental fluctuations.
However, mobile refrigeration – used in trucks, ships and buses – faces a dramatically different operational landscape. Saar explained: “The major difference when we talk about systems that are moving while they are in operation, it’s the vibration… and then all the potential faster temperature changes in the environment compared to stationary systems.” Broughton provided a relatable analogy, referencing vehicular systems: “You’re driving along, it’s 32°C, then you come to a dead stop – that does not happen in a stationary application.” Unlike a supermarket chiller, a truck or bus must constantly adjust to ambient temperature swings, sun exposure, wind and road conditions.
Despite these differences, stationary and mobile systems share fundamental refrigeration principles, including compressor operation, refrigerant flow, pipe velocity and oil management. Both types require careful attention to component sizing, lubrication, and system pressures to ensure reliable performance. As Saar emphasised, “Even though mobile applications face additional challenges, many of the same things you consider in a stationary system – like pipe velocity, oil transport, and valve sizing – still apply.”
Mobile refrigeration plays a crucial role in the cold chain, a global logistics network that preserves perishable goods from source to consumer. Products such as frozen food, fresh produce, and pharmaceuticals rely on precise temperature control during transport. Any failure in mobile refrigeration can lead to spoilage, financial loss, and potential public health concerns. John noted, “Maintaining the cold chain is critical. If the system fails or doesn’t perform as expected, the goods are at risk before they even reach the customer.”
For HVACR professionals, understanding these differences is essential. Designing stationary systems requires ensuring stability and energy efficiency over long operational periods. In contrast, mobile systems must balance reliability, flexibility and durability under constantly changing conditions. Vibration, temperature swings, and frequent start-stop cycles must be accounted for in every design choice, from compressor selection to piping layout.
The discussion also touched on industry trends. As fleets of electric buses and refrigerated trucks expand, power systems are evolving, but the fundamental challenges of mobility remain. Systems must still be robust, efficient and maintain product integrity despite motion and environmental stressors.
Ultimately, the conversation underscored the importance of understanding context in refrigeration design. Whether stationary or mobile, each application has its own operational realities that require specialised engineering. For students, engineers and logistics managers, this episode of Taking the Temperature on HVACR offers an insightful primer on how refrigeration technology adapts to the unique challenges of movement, temperature variance and cold chain management.