as well as the load, to the desired transit temperature prior to loading. And both refrigeration equipment manufacturers and the U.S. Department of Agriculture recommend shutting the unit off during loading. Yet some operators and their customers are not always comfortable with that approach.
An alternative is to balance the needs of the shipper’s cargo requirements with the hauler’s fuel economy needs in a practical and intelligent manner. Enter one of the newest reefer apps from Carrier Transicold, Door Man, which the company said can be programmed to optimize unit operation and fuel consumption based on outside ambient conditions that the shipper and hauler agree upon. "People are beginning to realize the value of this compromise," said Fragnito. "Haulers save fuel, which holds down costs. At the same time, shippers get the temperature integrity they require for their product. It’s a ‘win-win.’"
Door switches have been available for years and are used to shut down the refrigeration unit when trailer doors are opened. Carrier said its Door Man app adds control flexibility that allows the unit to be programmed to run in low speed, high speed or not at all, based on exterior temperatures. This can help conserve fuel while satisfying user cargo temperature requirements.
When choosing trailer door switches to optimize unit operation and control fuel consumption, Carrier suggests looking for switches that:
• Monitor and record door-opening events. Door switches can record all door openings in the unit microprocessor’s integrated data logger. Not only can this information be a helpful verification of deliveries, but it also can help to identify occurrences of potential break-ins, cargo theft or cargo tampering.
• Shut the unit off to save fuel when the doors are open during loading or deliveries, which is the traditional use of reefer door switches.
• Save fuel in low-speed mode. Locking out high-speed can cut fuel consumption dramatically while the doors are open, and yet still keep the unit operating per customer preferences.
• Automatically decide when and how to run the refrigeration unit to optimize fuel economy. Depending on outside temperatures, the refrigeration unit can be programmed to automatically shut down or run in low- or high-speed modes during door openings, adding automated, intelligent decision making to the process.
The shipper and the hauler agree on a range of outside temperatures at which the unit is allowed to run in low- and high-speed modes, or shut off completely. When the doors of the trailer are opened, the unit should automatically adjust its operation as programmed.
The best switches ensure that shutdown will occur when the doors are open and outside temperatures are below 39.5˚ F. Carrier said that programming its Door Man options can be done using the keypad of individual refrigeration unit controls—APX or Advance. Alternately, it can be programmed with a PC, using Carrier’s TRU-Tech software. One of the key advantages of PC setup is the ability to quickly load the configuration into multiple refrigeration units, the company added.
Given the importance of fuel conservation balanced with refrigerated product protection, the decision to use door switches and intelligent reefer control truly is an open and shut case!
