Plate Coolers

A plate cooler is a simple heat exchanger that captures the heat of warm milk and transfers it to the cold incoming water. There are two distinct benefits: First, the milk is pre-cooled - by the time is reaches the refrigerated storage tank. Second, water that needs heating for varied uses is pre-warmed.

What does a plate cooler do?

Milk leaves a cow’s body at 98 degrees Fahrenheit and needs to be cooled quickly to less than 40 degrees. Milk cooling is a significant percentage of a dairy farm’s electricity costs. An in-line plate cooler lowers the milk’s temperature before milk enters the bulk tank to be cooled further. Plate coolers cool milk quickly, which helps lower bacteria counts and is easier on compressors. An in-line cooler is one of the best energy investments in a dairy operation.

How does a plate cooler save money?

In-line precooling significantly reduces cooling and agitation time. When precooled milk is pumped into the bulk tank, compressors usually finish the cooling in only 10 to 15 minutes. When the bulk tank has to do all the cooling, the compressors may run 30 minutes or more.

How does it work?

In-line coolers are typically installed between the transfer jar and the bulk tank. A widely used in-line cooler design is in the form of a plate cooler. In-line plate coolers run 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, plate coolers can drop milk temperature by 30 degrees or more. Variables include the temperature of the water, the ratio of water to milk in gallons per minute, and how many times the milk passes through the cold water channels. In line cooling has been called virtually free cooling because the water used to cool milk would have been used anyway for the livestock or barn chores.

Water that is warmed from the milk cooling process can easily be used to heat the milk room, or perform other chores. One idea is to pipe the water to a tank in the holding pen so the cows have fresh warm water while they wait to be milked. Since cows prefer warm water to cold, they may drink more water and, subsequently, produce more milk. The money saved by installing an in-line plate 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.

In all likelihood the investment will pay for itself in as little as two years.

Your electric company may provide incentives for the installation of variable frequency drives on vacuum pump motors and ventilation systems. CET staff will help you with the process as needed.

The Energy and Small Farm Sustainability program is made possible by a grant from the Northeast Sustainable Agriculture Research and Education Program.

This material was adapted from "In-line Milk Cooling" by Wisconsin Public Service. Sign up for a free energy assessment of your small farm. Find out how you can save money on your electric bills and if your farm is a good choice for producing renewable energy.