Is there a formula to calcluate temperature rise within a shipping container due to direct sunlight?

Answer 1

Kind of.

There are a bunch of equations involved because several factors work together.

• You have to determine the angle of the sunlight because (you may have noticed this) sunlight at a shallow angle is less intense than sunlight coming straight down from directly overhead.
• You have to determine the geometry of the shipping container and how it is oriented relative to the incoming sunlight.
• You have to know the reflectivity of the surface of the shipping container.
• You have to know the thickness of the walls of the shipping container and the thermal conductivity of those walls.
• You have to know the heat capacity of the contents of the shipping container - whether it contains cargo or just air.
• You have to know the initial temperature of the shipping container and its contents.
• You need to know the temperature of the surroundings and whether there is a wind in order to be able to account for convective heat transfer to or from the container.
• You may have to know the emissivity of the shipping container and the temperature and absorbing capacity of the surroundings.

As you might guess, this gets a little complicated so, yes you could come up with a single formula but it would require knowing a lot of constants and variables and would not be simple or easy to use and the form of the equation would change as the environment changed and different factors increased and decreased in their relative importance. Most likely you would have to solve a system of equations to get your answer. You would probably get an answer a lot quicker that would serve most purposes by just going out to a shipping yard or dock and asking someone who has worked with freight for several years to give you an estimate based on their experience.