# Use of Phase Change Materials for Food Applications--State of the Art in 2022
## 2 Food Applications of PCM
### Food Storage and Transport
#### 2.2.10. Compartments That Are Fixed on a Van, Truck, or Trailer  
Compartments for the transport of temperature sensitive goods fixed on a truck, train etc. are common. Historically, ice as ice blocks, which melted and was then flowing away, was first used for their cooling. With the invention of heating and cooling devices like electrical heaters and compression coolers these became the new standard. Their advantages are significant: wide range and variable service temperature, as well as unlimited service time as long as energy for running them is available. Common on trucks and vans today is a diesel-driven compression cooler, installed outside the refrigerated space, typically on the front side somewhat above the driver compartment, with cold release inside the refrigerated space where e.g., food is transported by a heat exchanger and a fan for air motion. R&D on the use of PCM in that application area is already going on for more than a decade, as literature reviews in [48, 50, 51, 68]. Overall, several different approaches are discussed in R&D to modify cooling on trucks, differing in where and how the PCM is integrated, and also how it is charged. The smallest modification is just adding PCM to the overall system. Ref. [69] looked at PCM integrated into the walls, and found that it reduces heat input from the outside to the interior between 11 and 43%. Further R&D on integrating PCM into the walls are [70] (numerical). Ref. [71] make a detailed investigation for Malaysia. They compare the integration of PCM with that in buildings, specifically walls, to cut down average and peak heat transfer from the outside environment to the refrigerated space. According to their simulations, already 80 kg of PCM yield substantial load reductions and energy savings. Generally, because of the different thermal resistances, it can be expected that PCM in the walls buffers mainly heat input from outside, while PCM installed in the refrigerated space buffers the load in the refrigerated space in general thus also including door openings but not only. Ref. [72] (see [48]) investigated the configuration where a van with a regular  
Figure 10: PronGO® bag and box (source: both PLUSS Advanced Technologies Ltd.) and va-Q-tainer for large volumes (source: va-Q-tec AG, Würzburg, Germany). cooling unit was additionally equipped with PCMs slabs installed under the ceiling of the refrigerated space. Investigation was by numerical modeling, looking at the general performance and performance upon door openings. The investigations looked at the use of paraffins with melting points a few \({}^{\circ}\)C above freezing, and showed significant performance improvements during door openings. While just adding PCM to the overall system is a rather small modification of the overall system, larger modifications involve the change of the means of cold production or even its complete shift off the van or truck to external facilities and non-driving times. Ref. [73] experimentally studied cooling of the refrigerated space by a plate installed inside the refrigerated space, on the ceiling, filled with water as PCM, and a fan to improve convection between the surface of the plate and the refrigerated space. Refrigeration was achieved by a tank with Liquefied Natural Gas to (LNG) to run the car engine, however before getting there, the evaporated cold gas flowing through tubes immersed in the plate that contain the PCM. Ref. [74] investigated cooling the refrigerated space by PCM installed inside the refrigerated space, at its front. Experimental investigations were performed in tropical climate, on a stationary prototype, with the refrigeration unit outside attached to the refrigerated space. Initial cool down to \(-40\,^{\circ}\)C was done using off-peak electricity at night when the vehicle is stationary. Afterwards, independent cooling by the PCM was tested. The PCM used changes phase at \(-30\,^{\circ}\)C, has a latent heat of 175 kJ/kg, and was used in an amount of 275 kg.