Chapter 24

Winery Refrigeration

Refrigeration System

Mechanical refrigeration, often referred to simply as refrigeration, is a process by which heat is removed from a location using a man-made heat-exchange system. The most widely used refrigeration cycle method is mechanical compression. It has applications in both air conditioning and commercial and industrial refrigeration. As the name suggests, these types of systems transfer heat by mechanically compressing refrigerant into a low-pressure, cold liquid and expanding it into a high-pressure, hot gas. Refrigerants are substances that can boil at a wide range of temperatures with the application or removal of pressure.

Refrigeration Cycle

The job of the refrigeration cycle is to remove unwanted heat from one place and discharge it into another. To accomplish this, the refrigerant is pumped through a closed refrigeration system. Refrigerants, are chemical compounds (e.g., freon, ammonia, brine, or glycol) that are alternately compressed and condensed into a liquid and then permitted to expand into a vapor or gas as they are pumped through the mechanical refrigeration system to cycle.

Sizing a Refrigeration Unit

There are various ways to estimate the size of a refrigeration system needed for a winery. One simple rule of thumb is that 1 tonR is needed for each 1,000 cases of wine or beer to be produced. For instance, a 40,000-case winery will require a 40 tonR refrigeration unit. Another way to estimate refrigeration needs for wineries is to use a prediction of grape delivery during the course of harvest to calculate peak fermentor refrigeration loads on each harvest day based on expected fermentation kinetics.

Direct Expansion versus Secondary Loop System

In designing the refrigeration system, the winemaker can either choose a primary refrigerant system, often referred to as direct expansion, or a secondary refrigerant system. Primary refrigeration systems always have lower power requirements than secondary refrigeration systems. Secondary refrigerants are liquids (e.g., glycol, brine) cooled by a primary refrigerant, and which absorb heat from the product without a change in phase.

Direct Primary Refrigeration System

As already noted, direct expansion relies on the refrigerant undergoing a change of state from a liquid to a vapor as it moves through the evaporator.

Secondary Refrigerant System

A secondary refrigeration system is made up of 2 subsystems. Stage 1 of the system is a direct expansion system which chills the coolant utilized in stage 2 of the process. The coolant can either be water or a mixture of water/ glycol or brine which absorbs heat through the heat exchangers.

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