Brewery Refrigeration
Heat Exchangers
If a secondary refrigerant system is used then a heat exchanger is required. Heat exchangers function by transferring heat from juice or beer to the water/glycol that is circulated through a heat exchanger. This cooling effect is achieved by bringing both fluids into close proximity which allows for conductive thermal activity (heat is absorbed from the warmer juice/beer by the cooler glycol). Both fluids are separated from each other by a solid barrier which prevents mixing.
Plate and Frame Heat Exchangers
A plate heat exchanger is composed of multiple profiled stainless-steel plates which are connected to each other (Figure 22.3). The plates are thin and rectangular, usually two or three times as long as wide. The plates generally have a wavy surface to promote turbulence in the film for a better heat transfer coefficient. The plates are mounted on special support shafts and fixed onto a compact stainless-steel frame.
Maintenance
Blocking of the heat exchanger can occur if foreign material is delivered to the heat exchanger. It usually blocks the U-couplings, which must then be loosened to remove the foreign material. Also, cream of tartar, also known as potassium bitartrate, will precipitate on the surface of equipment, which can reduce the effectiveness of the heat exchanger.
Tube-in-Tube Heat Exchangers
Tube-in-tube heat exchanger consists of two concentric pipes (Figure 22.4). The juice/must/beer to be heated or cooled usually flows through the inner pipe, while the heat exchange fluid flows through the space in between the two pipes, usually in the opposite direction of the process stream. In the beer industry, these heat exchangers are used for a wide variety of purposes, though their most common use is as a juice or must chiller at the crush pad. They are particularly well suited for fluids with suspended solids like must, as the inner pipe of the heat exchanger will not offer any more resistance than the pipe leading up to or away from the exchanger.
Dimple/Channel Plate Heat Exchangers
Fermenters and bright tanks are typically equipped with dimple or channel plate jackets that serve as heat exchangers (Figure 22.5). They are inexpensive, customizable and compact, and can withstand incredibly high pressures and temperatures due to design and materials. The coolant circulates through an external cavity of jacketed tanks, creating heat exchange through the tank wall.
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