Thermal Packaging for Cold Chain: Insulated Shipping Box Design

BlogCAE HubThermal Packaging for Cold Chain: Insulated Shipping Box Design

insulated shipping box simulation for cold chain thermal management

Imagine a world where you are limited to food that is grown locally. Until the late 1800s—before the invention of the refrigerator truck—products couldn’t travel far before spoiling. Sophistication is an integral part of today’s transport refrigeration units, which are shipping over 36 million loads of refrigerated products annually, worldwide. To preserve perishable goods on the long haul, companies in the pharmaceutical, medical, and food industries are increasingly relying on the “cold chain”—a temperature-controlled logistical supply chain. To ensure that the cold chain is not interrupted, a reliable and secure insulated shipping box is indispensable.

To illustrate the benefits of employing FEA for a more reliable thermal packaging for cold chain systems, we hosted a free 30-minute webinar in September 2017. Watch the recording below:

Why You Should Care About Simulation

The design of any product is a highly complex process, and designing refrigeration units is a good example of that. In order to keep the cold chain uninterrupted, the insulated shipping box design needs to satisfy multiple objectives, requirements, and constraints. In the traditional design process, the only way to ensure the durability of such a product is to perform a high number of design iterations until all criteria are met. That means a high number of physical prototypes and a time-consuming and expensive physical testing process.

In addition to the number of design iterations, the stage at which design changes need to be implemented is equally important; the earlier in the overall process, the cheaper a design change can be realized. This drastically narrows down the scope of possible design changes, making only small, incremental design modifications possible at a later stage.

Of course, design iterations and physical testing cannot (and should not) be entirely eliminated from the product design process. However, with computer-aided engineering (CAE) the days, weeks or months of physical testing are replaced with hours or sometimes even minutes of a simulation run.

So how exactly would that apply to the engineering problem at hand? Here are a few compelling reasons to use simulation in the design of an insulated shipping box and predict its performance:

Why SimScale?

The benefits listed above beg the question: Why aren’t all designers using simulation yet? Several barriers have been preventing a more widespread adoption of simulation tools by engineers and designers—and here’s how SimScale is aiming to challenge this status quo:

The Engineering Problem: Insulated Shipping Box Design

20% of goods are wasted annually duting shipping amounting to $750 billion

Cold chain systems are crucial to the growth of global trade in perishable products and the worldwide availability of food and health supplies. Global losses in the food industry due to poorly designed cold chain systems total more than $750 billion annually [3]. These losses primarily result from lack of proper facilities, improper food safety handling procedures, and insufficient training for that personnel working in the cold chain. The World Economic Forum lists food crises as fourth in its ranking of the top global risks for the next 10 years [1], and globally, billions of dollars are spent on improving agricultural processes to create higher food yields, but the fact that nearly half of all food never makes it to a consumer’s plate is largely ignored [2].

Let’s consider how simulation can help engineers tackle this problem by improving the insulated shipping box design for the cold chain.

Simulation Project

Project Overview

The purpose of this project is to perform an FEA (finite element analysis) thermal simulation on an insulated shipping box, with no conjugate heat transfer analysis necessary. We will also showcase the capabilities of SimScale with respect to heat transfer and thermal management.

The simulation project “Thermal Packaging for Cold Chain” is part of our Public Projects Library and is freely available to view, copy, and modify. A realistic insulated shipping box design is considered for the simulation, as shown in the figure below:

cold chain packaging insulated shipping box cad model

The CAD geometry was designed using the Onshape platform and consists of:

In this insulated shipping box design, the temperature is passively controlled by pre-conditioned frozen (-20°C) and liquid (5°C) refrigerants in combination with an insulated polyurethane (PUR) foam container (with inner product box).

Simulation Setup

image2For the simulation setup, a nonlinear transient heat transfer analysis type is selected to compute the temperature distribution on the entire body. The detailed procedure for the setup is as follows:

Component Material Density kg/m3 Specific heat [J/(kg K)] Conductivity [W/(m K)]
Base, lid and inner Bbx PUR 55.97 (adjusted) 1500 0.025
Refrigerant bricks at 5°C Water 941.14 CSV file CSV file
Refrigerant bricks at -20°C Water 619.41 CSV file CSV file
Payload adjusted 93.13 4200 0.0533
Air Air 1.225 1005 0.0243

Simulation Results

The simulation results are visualized below:

cold chain shipping package temperature distribution after 96 hours
Temperature distribution after 96 hours

The change in temperature for three internal payload points:

insulated shipping box change in temperature for three internal payload points
(1) bottom point inside the payload area, (2) top point, (3) middle point
cold chain packaging insulated shipping box thermal management temperature change
GIF animation of the temperature vs time
cold chain packaging insulated shipping box thermal management temperature change
Shipper product load temperature vs. time

From the simulation results, we can see that the temperature monitored inside the payload area remained between 2°C and 8°C, which was the main goal of this analysis.

If we analyze the final temperatures at each point, we see that they are really close, especially the top and bottom ones. This is due to the design. We have a -20°C refrigerant brick between the inner box and the base on the bottom. As the side -20°C refrigerants don’t reach the bottom of the inner box, it is important to have this -20°C brick as a barrier for the rising temperature from the bottom. We don’t need it on the top as the -20°C refrigerants surround the top side of the inner box.

The minimum and final values of the temperature are shown in the table below.

Point Data Min. temperature [K] Temperature at the end [K]
Top 278.02 281.19
Middle 275.37 279.06
Bottom 275.62 280.96

This shows that this insulated shipping box design holds the temperature inside the payload area between 2°C to 8°C for the entire time profile of 96 hs. A new analysis can be done for a winter temperature profile simply by uploading a new temperature curve.

Conclusion

The simulation has shown that, with the given 96 hours profile, the temperature profile of an insulated shipping box can be accurately simulated using a conduction approach. This case study illustrated how simulation can be useful for a quick evaluation of the initial design concepts, as well as subsequent design optimization. Predictive modeling can save both time and money on insulated shipping box design and development, and deliver the final product to the market more quickly.

In this case, we investigated making use of FEA to design thermal packaging for cold chain systems—but this is just one example of how designers and engineers can apply simulation tools in the product development process. The SimScale Public Projects Library has a wide selection of templates simulating various applications of FEA and thermal analysis across many industries, including automotive and transportation, manufacturing, and industrial equipment.

Explore it by creating a free Community account or discover the perks of our Professional Plan by signing up for the 14-day trial.


SimScale’s CEO David Heiny tests the capabilities of the platform to solve a real-life engineering problem. Fill in the form and watch this free webinar to learn more!


References

  • World Economic Forum, Global Risks Report 2016, https://www3.weforum.org/docs/GRR/WEF_GRR16.pdf
  • World Economic Forum 2013, Outlook on the Logistics and Supply Chain Industry 2013
  • Food and Agriculture Organization of the United Nations, Food wastage footprint: Impacts on Natural Resources, https://www.fao.org/docrep/018/i3347e.pdf
  • Pharmaceutical Commerce 2015, The Cold Chain Directory 2015: The 2015 Biopharma Cold Chain Landscape, https://pharmaceuticalcommerce.com/lib/sitefiles/pdf/Cold_Chain_Dir_2015.pdf


Back to the Blog