Lecture+9.++Heat+Exchangers - UNIVERSITY OF CALIFORNIA...

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UNIVERSITY OF CALIFORNIA Department of Viticulture and Enology VEN 135 WINE TECHNOLOGY AND WINERY SYSTEMS 9. HEAT EXCHANGERS WINERY USES FOR HEAT EXCHANGERS Heat exchangers are used in winemaking in a range of different applications: 1. Must and juice cooling prior to skin contact or fermentation. 2. High temperature, short time (HTST) denaturation of oxidative enzymes in juices. 3. Temperature control during and after fermentation 4. Chilling wines for bitartrate stabilization. 5. Heat recovery from cold wines. The type of heat exchanger that is best suited to perform a particular function will depend on the special features of the particular task. For example, the cooling of musts will require large diameter tubing to minimize plugging by skins and stem fragments and the chilling of wines will require scraped-surface units to limit ice and bitartrate deposition in the unit. TYPES OF HEAT EXCHANGERS 1. JACKETS A common method of heat transfer in a winery setting is a jacketed tank. Jackets can be ordered in various configurations. The most common types of jackets are open jackets that may have baffles to direct flow, half-pipe arrangements where a half-pipe is welded onto the tank surface in a helical fashion, and dimpled where a pattern of spot welds interrupts the coolant flow to increase heat transfer. Any of these geometries can be “zoned” (multiple inlets/multiple outlets) for more efficient heat transfer. Advantages and disadvantages of the various types of jackets can be found in Figure 9.1 (from Precision Stainless). 2. TUBE IN TUBE/SHELL AND TUBE EXCHANGERS. Tube-in-tube heat exchangers are the simplest form of shell and tube exchanger. A small diameter tube (usually 25 to 50 mm) carrying the fluid to be cooled (or heated) is mounted within a larger diameter tube. The cooling (or heating) medium moves in a counter direction in the outer annular region. Tube-in-tube units with 75 mm diameter tubes are used for must cooling and those with tubes >50 mm in diameter are suitable for juice and wine cooling. They can also be used for cooling fermentations by being placed
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in the line that is used for the pump-over operation. An example of a tube-in- tube must chiller is shown in Figure 9.2. Shell and tube units used for juice and wine applications often have many tubes within the shell. If both fluids flow in one direction (i.e. without any change of
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Lecture+9.++Heat+Exchangers - UNIVERSITY OF CALIFORNIA...

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