Temperature characteristics
Preservation and stabilization of the product temperature
The thermal covers with middle closure system or insulated covers are used to preserve or stabilize the temperature of the products, which are protected by the thermal cover, as long as possible. The time that the temperature can be preserved of stabilized, or the speed of temperature increase or decrease, is depending on the insulation quality. Thermal covers or insulated covers with middle closures are manufactured with a certain Temax insulation material which have a certain insulation quality (R-value or U(k)-value). The higher or thicker the insulation quality, the longer the time of temperature preservation or the slower the speed of temperature change of the products inside the thermal cover.
External convection flows due to open thermal bridges – cold bridges
Next to the insulation quality of the thermal cover with middle closure, the stability or deviation speed of the temperature of the product is also depending on the presents of open thermal bridges or open cold bridges on the thermal cover and packaging set-up. Open thermal bridges are locations in the design or set-up of the thermal cover where an external convection flow (air flow) can exist which has a very big impact on the speed of temperature change. It is therefore very important that open thermal bridges are avoided at all times.
Adding extra thermal energy generators - Gel Packs – Dry Ice – PCM’s Phase Change Materials
When conditioned or time-temperature sensitive products are protected from external temperature influences with a passive cooling systems such as thermal covers with middle closure systems, the goal is to purely use the available thermal energy of the products to maintain and stabilize the temperature of the products as long as possible. As we know, the result of this stabilization is depending on the insulation quality of the thermal cover combined with possible convection flows and the thermal energy of the products combined with the temperature difference (inside-outside). If the temperature cannot be maintained according to the preferred time-frame, the time can be extended by increasing the available thermal energy. This extra energy can be generated by all kind of passive cooling systems such as gel packs – ice packs – dry ice – PCM’s Phase Change Materials.
Insulating the bottom of the pallet
Most roller containers have bottoms which are not completely closed so a convection flow (air flow) can appear meaning that the air can flow through these openings. Therefore it is very important to seal or insulate the bottom of the container before loading the chilled or frozen products. An insulated bottom will increase the temperature results significant. To insulate the bottom a on-way use insulation or cardboard can be used.
Air in the roll container = negative effect on the available thermal energy
When roll containers are filled with conditioned products, it can happen that the roll container is not completely filled. Yet the roll containers have sidebars which stand higher than the filled goods. This means that lots or air can go into the roll container when the thermal cover is placed over the side-bars. Therefore it is very important that this air is kept to a minimum or an insulated blanket is being placed on top of the goods to protect it from the air above. Also it is important to bring-on the cover in the cold storage room so the air above the goods is the same as the temperature of the goods. Hot air combined with chilled products will have a negative temperature result.
Thermal equilibrium: Always remember that two different temperatures combined in a single thermal packaging system will create a natural thermal equilibrium in which a mutual temperature is created. The final temperature is depending on the thermal energy of each individual product or substance
Insulation qualities
