Winery Refrigeration
Heat Exchangers for Wineries
If a secondary refrigerant system is used then a heat exchanger is required. Heat exchangers function by transferring heat from juice or wine 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/wine by the cooler glycol).
Types of Heat Exchangers
A heat exchanger refers to any equipment that transfers heat between two fluids, these are very useful, if not necessary, for several processes in wine production. Various heat exchangers are available for use in different industrial cooling applications. The most commonly used types are: (1) tube-in-tube heat exchangers, (2) plate heat exchangers, and (3) dimple or channel plate heat exchangers.
Tube-in-Tube Heat Exchangers
Tube-in-tube heat exchanger consists of two concentric pipes (Figure 24.3). The juice/must/wine 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 wine 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.
Plate Heater Exchangers
A plate heat exchanger is composed of multiple profiled stainless-steel plates which are connected to each other (Figure 24.4). 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.
Dimple or Channel Plate Heat Exchangers
Dimple or channel plate heat exchangers offer the best of both above kinds of heat exchangers - they are inexpensive, customizable and compact, but can withstand incredibly high pressures and temperatures due to design and materials (Figure 24.5). In general, dimple or channel plates are a good option for passive heating or cooling a tank where refrigeration or heating would otherwise be expensive.
Maintenance
Blocking of the heat exchanger can occur if foreign material is delivered in the grape loads and move through the grape crusher to the heat exchanger. It usually blocks the U-couplings, which must then be loosened to remove the foreign material.
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