How Vacuum Cooling Works - A H Ridsdale

What can you cool?

Vacuum cooling can be used sucessfully to cool a number of different products:-

Salads
Leafy vegetables
Mushrooms
Herbs
Soft fruits
Sweetcorn
Bread
Bakery products
Cooked meats
Cut flowers
Lawn turf
Soups and sources

The process draws heat out of every part of the surface area of the product being cooled
equally therefore even products that are placed in boxes or crates and stacked on pallets can be cooled efficiently and uniformally.

Suitable products for vacuum cooling are ones which readily give up a percentage of their water, without affecting product quality.

Contact us to discuss how vacuum cooling can be used to help your business.

Advantages

Fast
Extended shelf life
Consistent product temperature
Even product temperature
Efficient energy consumption

Vacuum cooling is a very much faster method of cooling compared to blowing cold air around the products in a bulk fridge – and uses considerably less energy to achieve target storage temperature.

Typical cycle times of 20-30 minutes for total product cooling.

Achieving the best storage temperature as fast as possible after harvest or production can obviously increase the quality of any perishable product as the time spent at risk of deterioration is reduced. Vacuum cooling has been show to reduce wastage, improve the quality and greatly extend the shelf life and use by life.

Benefits of faster temperature stablisation can give other unexpected advantages. Goods can be transported further and for longer transit times without compromising quality or food safety.

How does it work?

Vacuum cooling works because of the reaction of water to the surrounding air pressure.

As we all know water will turn into water vapor (steam) if it reaches a temperature of 100 degrees celsius at atmospheric air pressure (1013mbar at sea level). If we were to take the same water to the top of Mount Everest we would find that due to the elevation above sea level of 8848m (29029ft) the air pressure will have reduced to around 346mbar. At this air pressure the water would vaporise at 71°C. In the same way, if we place the water in an vacuum chamber and reduce the air pressure even further, for example down to 7mbar, the water would vaporise at 2°C.

As the liquid changes to a vapor it needs heat energy to complete the change of state, this is known as latent heat of vaporisation. The vaporising water in the product takes this heat from the surounding mass of product therefore reducing the heat energy contained within the item, and hence the product is cooled.

In the vacuum cooling process we can achieve the pressure conditions needed to make the water inside the products to be cooled evaporate under our control. In fact the control is so accurate we can set the exact required product temperature and achieve it reliably time after time.

Machines for different applications

Vacuum coolers can be constructed to suit a wide range of applications from a single pallet space or bakery trolly to much larger machines which can accommodate larger loads (eg.20 pallets).

A small number of coolers have also been produced that can contain a bulk tipper trailer complete with its load of around 30 tonnes to be cooled.

Product can be placed in and out of the cooler vessels by a variety of methods.

With the larger coolers different types of powered conveyor sytems are available dependent on the type or mass of the pallets or other product transport systems.

Coolers can be specified to have either 1 or 2 doors. The 2 door machines can be combined with infeed and outfeed conveyor systems allowing automatic operation.