# Temperature of shipping container

1. Sep 10, 2013

### woody726

How do I calculate the surface temperature of a shipping container's roof over 24 hours? All weather and sun parameters are known and I use an energy balance equation, but the contribution of the inside of the container causes the calculated values (rise too fast) to differ from the measured ones.

2. Sep 10, 2013

### dauto

• The unknown contentents of the containers will produce - well - unknown effect on the result

3. Sep 10, 2013

### SteamKing

Staff Emeritus
Sometimes, the contents of shipping containers have been known to ignite (see calcium hypochlorite). That could really throw off your calculations.

If you are treating the container as a 'black box' (where the contents are unknown), I don't know if it is feasible to construct a very accurate model, since you have no practical way to account for the heat absorption of the contents during the day.

4. Sep 11, 2013

### woody726

The container is empty (air), and I use a model considering solar (shortwave) absorption, longwave atmospheric irradiance aborption, graybody emission from the container and convection. But the contribution of the inside of the container is what I am not sure of since currently the roof is considered simply as a sheet of metal. I assume net heat flux=0 for a given set of environmental parameters that are known for every minute over 24 hours: air temperature, solar irradiance, relative humidity, air pressure, wind velocity. The thermodynamic parameters for the container roof are also know: specific heat capacity (600 J/(kgK)), conductivity (50 W/(mK) ), density (7000 kgm-3), short (0.88) and longwave (0.9) absorption coeff, emissivity (0.88), and thickness (3mm).