In food processing, thermal transfer is like gravity: What goes up must come down. For many liquids and solids, down is somewhere south of 5°C/40°F, making refrigeration a core process.

Freezing and cooling finished goods require energy, and better managing energy inputs is a priority. Green initiatives, lean programs and rising utility costs are prodding manufacturers and their supply partners to consider alternative approaches that boost thermal-transfer efficiencies. Whether the objective is to lock in positive attributes with freezing or preserve fresh food at refrigeration temperatures, innovative technologies are finding a receptive audience.

Hydro cooling is a case in point. Refrigerated soups, side dishes and other commissary-style products traditionally use refridgerated air at -10°F  to lower the temperature of packaged foods below 40°F. Management at Lima, OH start-up Kettle Creations were inclined to go that route two years ago when local authorities ruled out an anhydrous ammonia system because of the close proximity of a heart clinic. The project engineer had a better idea: Why not leverage the superior heat-transfer of water to lower energy demand? Campbell Soup pioneered the process two years earlier at its StockPot division (see “Soup’s on at Stockpot,” Food Engineering, December 2008) when it installed four spiral coolers from Coastline Equipment Inc. Concluding what worked for soup in Everett, WA should work for mashed potatoes in Lima, Kettle’s owners opted for hydro cooling.

About 3,000 stainless steel nozzles spray cold water directly on 170°F filled containers as they wend their way down the 30-tier spiral, according to Rene Janzen, sales engineer at Bellingham, WA-based Coastline, spraying 4,000 gallons a minute. A treatment system filters, ozonates and recirculates the water. Dwell time is 90 minutes. The process is gentler on the product than frigid air, Janzen maintains, and cold air can turn the corners of the packages brittle and susceptible to cracking.

General contractor Keith Pohlman, president of All Temp Refrigeration Inc., Delphos, OH, plumbed the spiral system to a centrifugal chiller and added another energy enhancement: a heat exchanger that extracts latent heat from the containers and reuses it to heat the floors.

Pohlman’s chiller uses 134a refrigerant, the replacement for the chlorofluorocarbon (CFC) R22 (see related story below).

The ozone depletion caused by CFCs led to a worldwide ban on Freon production, and programs like the EPA’s GreenChill that encourage retailers to find replacements for CFCs and hydrochlorofluorocarbon (HCFC) are gaining steam. Critics like Bruce Badger, president of the International Institute of Ammonia Refrigeration, maintain “the new refrigerants being concocted to reduce ozone depletion are significantly less efficient” than the coolants they replace. An EPA spokesman sharply disagrees, pointing out “the energy-efficiency of a refrigeration system depends on many factors.” Hawaiian inventor Richard Maruya recently gained EPA approval for HCR188c, the first pure hydrocarbon refrigerant. In a comparison with 134a, Maruya demonstrated his refrigerant draws 48 percent less power and requires only one-fourth the charge.

Maruya targeted automotive air conditioning and home refrigerators for his blend of propane, butane and other hydrocarbons, which carries the ASHRAE designation R441A. Engineers have greeted his coolant with skepticism, particularly over flammability issues, but Maruya insists the refrigerant’s small charge “makes the risk assessment a nonfactor.” To prove the skeptics wrong, he plans to charge a 50-ton system outfitted with a safety valve to automatically lower pressure in the event of a leak at the state fairgrounds in Sacramento, CA this summer.

                                                                                                         Source: www.foodengineeringmag.com