Desiccants Melt Away Frost Problems in LA Facility
K-Pac's 18-acre development offers an array of transportation services to importers, exporters, and domestic shippers of refrigerated commodities. Core services include cold storage, distribution, transloading, United States Department of Agriculture inspection, electronic data interchange (EDI), off-dock container freight stations, computerized inventory management, and direct rail service via Union Pacific/Southern Pacific and Burlington Northern/Santa Fe railroads.
The facility was constructed using a "rack-supported" design or built from the inside out. Its freezer building measures 120,940 sq ft and includes two small coolers to temper fruits and vegetables and one large freezer for storage of frozen foods and blast freezing of unfrozen foods. The facility has 28,935 sq ft of chilled capacity and 92,005 sq ft of frozen capacity.
The coolers have a 65?F range, between -30? and 35?, depending on product cooling needs, while the large freezer is maintained at a constant -30º. The combined freezers offer a total of 26,000 pallet positions.
Humidity + Cold = ProblemsIn 1999, K-Pac faced a number of operations difficulties that were directly tied to high humidity levels. As is the case with any cold storage facility experiencing high humidity, moisture condensation caused ice to form on floors and doors and hindered loading and unloading operations. The ice posed a threat to employee safety and had to be chipped or melted off by hand - a time-consuming job for workers and an added labor cost.
"Whenever you have a big temperature differential, you automatically have high humidity," said Bill Johns, facility manager for K-Pac. "We were seeing a lot of ice and frost build up on and around our freezer doors because of the high humidity. This extra moisture increased our defrost cycles. On a regular basis, we had to use ice chippers to remove the ice from around the doors."
"Ice that formed on the floor made it difficult for our forklift operators to brake on the slippery surface. This slowed down loading and unloading operations," added Johns. "The efficiency of our operations and safety of our employees were definitely being affected by the humidity levels."
K-Pac also realized that it could reduce energy costs by purchasing a system to help take the water load out of the air. With a dry loading dock, refrigeration coils operate more efficiently and defrost less frequently, reducing electrical power costs.
Trial Run Paves the TrailK-Pac decided to take action. After speaking with Munters Corporation (Selma, TX) engineers about desiccant dehumidification for refrigeration plants, K-Pac requested an in-plant demonstration. "We ran the demonstration unit for three or four weeks in June and part of July ," said Johns. "The Southern California Gas Company (SCGC) monitored the loading dock temperature and humidity during the demonstration and participated in the evaluation." Near the end of 1999, K-Pac managers approved a proposal for installation of a FreezAire F30, a FreezAire F10, and a gas-driven engine.
K-Pac hired Precision Refrigeration (Los Angeles) to install the FreezAire units. The job took about three days and went extremely smooth because of extensive preplanning, says Igor Cherdak, Precision Refrigeration's president. "We hadn't installed this system before, but it was pretty straightforward, there were no problems, and we were on schedule," he says.
In May 2000 the installation was complete. The F30 unit was mounted on the roof at the north end of the facility above the loading dock with a weathertight seal and thermal barrier and the F10 unit was installed on the smaller south dock of the facility.
The gas-driven engine passed Air Quality Management District testing and is close to being certified for operation. Once it is running, the jacketed water from the gas-driven engine will be used to heat water and to preheat the reactivated air of the F10 unit. When the hot water is available, it will reduce the load for the reactivation air gas burner and save energy.
Cool BenefitsAccording to Johns, the Munters dehumidifier is performing as planned. "We noticed the benefits of installing the FreezAire F30 system during the first week," said Johns. "Currently, the loading dock is maintained at 50 to 55¿ and the humidistat is set at 40% rh. The unit cycles on and off and keeps the rh between 40 to 50% by the freezer doors, right where we want it to be," he adds. By removing moisture from the air in loading dock areas and preventing humidity from condensing on floors or invading storage areas, the units have increased efficiency and safety of operations.
"The forklifts brake much better with dry floors and they run a little faster now," said Johns. "And icicles and snow no longer develop on the ceiling. In addition to providing a safer working environment for employees, the units have decreased truck loading and unloading times by keeping the loading dock dry, and improved product quality by preventing frost build-up through consistent temperatures," said Johns. "And there's less of a need to defrost because moisture is removed through desiccant attraction, rather than through condensation."
Steve Rawski, senior account executive for SCGC says that while data is still being analyzed, the system has without a doubt provided noticeable energy and cost savings. "The people in K-Pac Operations are of the perception that the system has saved them money, but we're probably still a few months from being able to quantify it," he says.
"We are very pleased with the performance of the Munters dehumidifiers," says Johns, adding that the company is considering adding another FreezAire unit to an uncontrolled loading dock on the other side of our building that's frequently opened during the week.