Developing the art of transport cargo refrigeration from the primitive days of dumping blocks of ice aboard trailers to today’s sophisticated systems and their efficient condensers, environmentally-friendly refrigerants, and precise microprocessor-based controllers has been a long, arduous, and, you might say, pretty cool saga.

But the two major players in today’s reefer market are by no means resting on their perishable, temperature-controlled laurels. Both Thermo King and Carrier Transicold see this market as a constantly changing matrix of desires, demands, and technology.

“Today’s reefer units are far more powerful and efficient than those of past decades-but then, they must be, because customer demands have increased, too,” says Dick Smith, veteran sales and marketing executive at Thermo King, based in Minneapolis. “It wasn’t that long ago that fleets were running 96-inch-wide, 45-foot-long trailers, and the insulation was three to four inches thick. Now many of the units are 102 inches wide, 53 feet long, and the walls have been thinned to maybe an inch and a half of insulation.

“That obviously helps with the cubic space for cargo . but it’s a lot more challenging to refrigerate. The ‘UA Factor’ measure of a trailer’s ability to resist warming of the interior air, which was maybe 110 with those earlier units, is now at least 140, and in some cases it’s as high as 200.”

That’s why Thermo King developed a reefer system they call the Magnum, which employs a reportedly first-in-the-industry powerful “screw” compressor-with 80% fewer moving parts than a reciprocating design-that can generate 30,000 Btu/hr to establish a minus-20 degrees F environment even when outside air temperature is 100 F.

“That’s quite a jump in capacity, when you think that for most of the Sixties and Seventies our traditional families of NWD-nose-mount, water-cooled, diesel-reefers produced about 11,000 Btu per hour to achieve that minus-20 level, and even a typical current unit will produce about 21,000 Btu,” Smith notes. “But the types of ‘boxes’ operators are running these days demand a lot more effort from the reefer system.”

Thermo King’s current line-up of trailer systems also includes the SB-III SR (featuring an Electronic Throttling Valve and the MP-VI controller, combining to provide a claimed 40%-faster temperature pulldown than would be possible without the ETV); the Super-II SR (top of the “Smart Reefer” family with built-in performance-monitoring microprocessor); and the electrically powered NWE Max II (cools or heats, and can be mounted on a trailer or in the wall of a warehouse). A quartet of straight-truck units-producing from 4500 to 10,000 Btu/hr to maintain -20 F-similarly covers off the P&D world. All these units employ R-404a refrigerant.

The challenges of identifying and meeting the needs of reefer operators are just as intense at rival Carrier Transicold, headquartered in Syracuse, N.Y. Down at Carrier’s production complex in Athens, Ga., director of marketing Neal Walsh shares some observations:

“There’s a demand for higher capacity,” he begins, “but a specific type of higher capacity. Contract carriers want to be able to pick up a load of lettuce one day, and go down the street and get a load of ice cream the next day. They want equipment with the flexibility to let them do that. And at the same time, of course, they don’t want their maintenance costs to go up, or to suffer any compromise in reliability.

“Basically, they want to be able to do everything with a 53-foot trailer that they could do with a 48-footer.”

In the daycab world, Walsh sees a long-term trend towards “composite”, multi-compartment/multi-temperature distribution, where radically different cargoes (say, “perishables” at +35 F and frozen meat at -20 F) need to be carried at the same time in the same trailer.

“In past designs, reefer systems tried to just channel the same cooled air by ductwork to each compartment the trailer might be subdivided into, using adjustable louvers to restrict the output so a compartment that needed a higher temperature would simply have more ambient air mixed in,” Walsh explains.

“But this didn’t produce consistent temperatures,” he recalls. “The solution was to install a separate evaporator in each compartment,” he adds. “That gives you the basic evaporator up front, handling the nearest compartment, and-further back along the ceiling-as many more as the configuration demands. Each can be set to a different temperature.”

Carrier’s answer to this is the “Genesis” line of remote evaporators (available in the TM1000 and TM900 models). Walsh claims that these units offer 100% more air flow than traditional remote units, and cooling capacities 80% to 100% greater.

“Now, if you want to put ice cream in the back and freeze it solid, but lettuce in the front compartment and just keep it cool, you can,” he asserts.

“Traditionally, remote evaporators simply didn’t have the capabilities to really provide sub-zero temps in the rear of the trailer.”

Carrier’s other offerings range from the Ultima 53 (specifically designed for the thin-wall 53-foot-trailer environment), through the workaday, multi-application Ultra and Ultra XL family, to the Extra and Optima (these last two are targeted at the non-frozen perishable cargo world rather than sub-zero-F requirements, although they can handle extra-low temps in smaller-sized trailers). The Supra, Tempra, and Integra lines address straight-truck needs.

Most of these Carrier products employ older but more economical R-22 refrigerant as standard, although R-404a is available as an option. Since R-22 still contains a small amount of ozone-depleting chlorine (unlike R-404a), international environmental agreements will see it discontinued in newly built equipment in the year 2010, and even for replenishing units in the field come 2020. Walsh doesn’t see this as a drawback for Carrier’s current customers or prospects, however.

“I’d say the typical service life of a reefer unit is maybe 15 years for daycab applications and eight to nine years in the over-the-road environment,” he estimates. “So anyone buying an R-22-equipped unit today could still look forward to a full lifespan, with no concerns at all about that refrigerant.

“And, in fact, looking back to when the chlorine-heavy R-12 and R-502 refrigerants were phased out, manufacturers like DuPont came up with acceptable synthetic look-alikes that allowed R-12/502 equipment to keep on running to the end of their normal service cycle anyway,” he adds. “When the year 2020 comes along and R-22 is eliminated, I wouldn’t be surprised if similar options are offered.”

Looking ahead to future demands in the reefer marketplace, Neal Walsh expects to see customers refocusing on issues like maintenance cost, operating cost, and reliability.

“As 53-foot trailers became permitted in more and more jurisdictions, it seemed to be enough for reefer operators to simply show that they could offer temperature-controlled service in those bigger units,” he suggests.

“But now that the novelty has worn off and 53-footers are commonplace, operators are getting back to the basics, demanding products that give them maximum efficiency.”

Pressure will continue for even thinner-walled insulated trailers to maximize payload in both cube and tare weight. This will be part of a major push for still-higher-payload trailers in the future. And both Carrier and Thermo King appreciate the impact of computerization on their products, and expect even more sophistication in areas like continuous monitoring of reefer operation and cargo temperature, with automatic reporting back to the carrier and even directly to the customer through data-logger units that employ satellite communications.

“Two-way communication presents some possible concerns, though,” one industry professional notes.

“If it were possible to remotely command a reefer unit to turn back on once a signal is received that it’s stopped operating, what if at that moment a technician or the driver were working on the unit, and had his hands against a drive belt or other moving part? You’d want to have an absolute fail-safe feature so no injuries could occur.”

Another wrinkle is the concept of a self-regulated ability to guarantee the “thermal integrity” of temperature-controlled cargoes: i.e., developing a system that could confirm that any given cargo was at all times kept within the temperature limits specified by the shipper.

This is part of a larger concept called HACCP (Hazard Analysis Critical Control Points), a detailed procedure that stipulates the points in a process (for example, keeping meat products safely chilled right from the slaughterhouse to the supermarket, to eliminate growth of bacteria that could harm the end user) where dangerous conditions are likely to develop.

A HACCP (pronounced “hasp”) plan would specify what conditions must be maintained in a given activity or process, and what constitutes acceptable confirmation that these were met. “You’ll see significant developments among all the players in the ‘cold chain’ needing to police themselves to guarantee their performance,” this observer states.

“Unless there’s some revolutionary breakthrough in processing that does away with the need to refrigerate cargoes at all, I expect we’ll all have to be prepared to ensure that carriers can demonstrate 100% compliance with the shipper’s thermal demands.”