Editor's note: This contributed article explores in detail the specific uses, physical design characteristics, energy consumption considerations and the on-going maintenance of heat exchangers in modern dairy installations.

In today's supermarkets consumers can pick from a wide variety of dairy products with new offerings appearing on a regular basis. This has necessitated subtle design changes of heat exchangers used in the dairy industry. While a heat exchanger is in essence a basic piece of equipment, manufacturers have incorporated specific designs to accommodate the specialized requirements of dairy processors.

Plate heat exchangers are used for a variety of purposes in dairy processing operations. Some major applications include HTST units (for milk, cheese-milk, ice cream), raw milk receiving coolers, and by-product (yogurt, cream) heater/coolers. Scraped surface heat exchangers are used for large particulate laden products or products which tend to crystallize during processing. There are numerous factors governing the design of a heat exchanger. For instance the product type, flowrate, temperature profile, pressure drop considerations and future expandability requirement are important design criteria when sizing a unit.

Heat Exchanger manufacturers strive for constant improvement in designs to enhance plant productivity. The physical designs of plates have evolved over the years. For fluid milk products, a herringbone or chevron plate pattern will allow the most efficient heat transfer and reduce consumption of utilities such as hot water, chilled water or glycol. More viscous products such as ice-cream mix and yogurt require reduced flow resistance; hence the use of 'wide-gap' style plates that allow lower pressure drops and increase CIP response. An expanded inlet design and a wider or "dairy size" gap is preferable for such applications to resist fouling. For very viscous products such as mayonnaise or sweetened condensed milk an expanded inlet design and wide gap/high pressure plate is suitable for heating or cooling.