In-line milk cooling

In-line cooling uses 50% less electricity, cools milk faster

Milk leaves a cow's body at 98° Fahrenheit and needs to be cooled quickly to less than 40°. Knowing this, it is easy to believe that milk cooling makes up about 18 percent of a Wisconsin dairy's total energy costs. By installing an in-line plate cooler, milk temperature is lowered before entering the bulk tank to be cooled further. This technology has proven its worth for two decades, and recent studies find it can reduce cooling costs by almost 50 percent. In-line cooling also cools milk faster, which helps lower bacteria counts and is easier on the compressors. An in-line milk cooler is one of the best investments you can make in your dairy operation.

Less electricity is used

By partially precooling milk before it hits the refrigerated bulk tank, the bulk tank compressors don't need to work as hard to cool milk down to storage temperature.

In fact, in-line cooling has been found to cut the electrical cost of cooling milk by almost 50 percent. This savings is possible because milk is precooled up to 30° or more, requiring that the compressors run approximately 10 to 15 minutes. Conventional cooling, in which all cooling is done in a bulk tank, requires that the compressors run approximately 30 to 45 minutes to cool the milk.

Enhance your dairy's bottom line by using less electricity while milking. Simply by using well water to partially cool milk prior to entering the bulk tank, an in-line cooling system can pay for itself in two years.

A recent study found that almost any size dairy can cut its electrical use for milk cooling by almost 50 percent with in-line cooling. Milk cooling is one of the largest energy draws on a dairy, so this could mean big savings. A different study looked at total annual energy savings from in-line cooling for different size dairies. It found that the larger the dairy, the more in-line cooling can reduce the total annual electric bill. This makes sense because the larger the dairy, the more milk cooling is done, and the savings potential is greater.

Number of cows Reduction of total energy use due to processing kWh/yr reduction
60 15% 3,500 kWh/yr
200 25% 11,400 kWh/yr
400 29% 22,500 kWh/yr

R.W. Peebles, D.J. Reinemann, R.J. Straub, Presented as ASAE Paper No. 93-3535.

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Milk is cooled faster

In-line precooling significantly reduces cooling and agitation time. When precooled milk is pumped in, the bulk tank compressors finish the cooling in only 10 to 15 minutes. Faster cooling increases the capacity of the bulk tank because a higher volume of milk can be cooled at once. Without precooling, a large volume of warm milk poured too quickly into the tank makes it difficult to cool the milk and keep it cool-especially when warm milk is blended with cooled milk. In-line cooling also reduces the wear and tear of the cooler's refrigeration system by giving it a big head start.

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Improves milk quality

Improper milk cooling is one of the leading causes of high bacteria counts in milk. The faster milk is cooled once it leaves the cow, the better: storage below 40 degrees stops or substantially reduces most bacterial growth. In-line cooling uses well water to cool milk by 10, 20 or 30 degrees or more before it enters the bulk tank, enabling the compressors to finish cooling the milk in less time. Dairy operators using in-line cooling can be assured that their milk meets these temperature regulations:

  • Milk pumped into the bulk tank should be cooled to 50 degrees within the first hour and to 40 degrees within the second hour
  • Milk added at subsequent milkings should not raise the temperature of the total milk in the bulk tank to above 40 degrees

In-line Milk Cooling

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In-line technology is proven

In-line milk cooling is not a new technology; it has been gaining in popularity on dairy farms for two decades. In-line coolers are typically installed between the transfer jar and bulk tank. A widely used in-line cooler design is in the form of a plate cooler. In-line plate coolers run well water and milk in opposite flow channels over a series of metal plates. Milk is cooled as its heat is transferred to the cool water on the opposite side of each plate. Depending on the system, in-line plate coolers can drop milk temperature by 30 degrees or more. Variables include the temperature of the well water, the ratio of water to milk in gallons per minute, and how many times the milk passes the cold-water channels. There are many sizes of plate coolers available to fit any size dairy: from stanchion barns to double-50 parlors.

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Warmed water can be reused

In-line cooling has been called "virtually free cooling" because the well water used to cool milk would have been used anyway for the livestock or barn chores. The warm water resulting from milk cooling can easily be used to water livestock, heat the milk room or perform other chores. One idea is to pipe the water to a tank in the holding pen so cows have warm, fresh water while they wait to be milked. Since cows prefer warm water to cold, they may drink more water and, subsequently, produce more milk.

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Variable-speed pump teams well with in-line cooling

Variable-speed milk pumps save a lot of energy by adjusting the speed of milk through the lines. When teamed with an in-line cooler, the variable-speed pump can maximize precooling by slowing the milk's speed through the cooler. This allows more time to transfer heat to the well water. Your WPS Agricultural Consultant can give you more details about variable-speed pumps.

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Pays for itself in about two years

The money saved by installing an in-line cooler depends on several factors such as herd size, number and size of compressors, type of Freon used, and the age of the bulk tank. WPS estimates that the investment can pay for itself in as little as two years.

Use the milk precooler calculator to show how you can save on energy costs by using a milk precooler.

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For more information

To learn more about how in-line cooling can help you reduce the cost of cooling milk, call WPS at 877-444-0888. You may want to ask about additional energy-saving measures that can help you realize higher profits on your dairy operation.

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