Temperature rise in chilled fluids due to ambient air temperature rise

[Richard Chivers]

We are based in the UK and have a chilled storage facility that holds 1500 tonnes of fruit juices and fruit pulps, contained in double lined bags within steel barrels, at lower than 5 centigrade.

I would like to carry out a risk assessment on ambient temperature rise and its ability to raise the temperature of our product. I’m imagining complete failure of our refrigeration due to power loss. What I don’t know how to calculate is the amount of heat needed to raise the temperature of 1500 tonnes of fluid by one degree centigrade. A quick Google search told me that:

The specific heat capacity of water is 4,200 joules per kilogram per degree Celsius (J/kg°C). This means that it takes 4,200J to raise the temperature of one kg of water by 1°C.

A Joule is one 3600th of a watt-hour, how do I convert that to ambient air temperature and how can I relate that to product temperature rise?

I appreciate the shape of the containers and the specific heat of the product will have an effect, but I would like to get an idea of the probability of an issue arising but at that point I became lost anyway.

As an example, I would like to be able to carry out my risk assessment and say ‘It will take X hours per degree centigrade in the ambient air to raise the temperature of 1500 tonnes of fluid by one degree.’

Can anyone give me a direction on this?

Yours hopefully,


Richard Chivers