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Pharmaceutical Manufacturing and Packing Sourcer

Ready, Steady, Vapourise

Richard Harrop at SCA Cool Logistics gives an insight into the benefits of evaporative cooling and its wide range of applications

There are more of us than you may think: people who believe that owning a classic car is the route to all happiness. I bought mine on a cold January afternoon and drove it every day until summer. What eventually stopped me was the result of sunlight on black PVC seat covers. A few weeks of hunting around for a company that could retro-fit air conditioning into classic cars finally led me to discover an item called a ‘swamp cooler’. This clever device is mounted on a side window of the car, half in and half out. It is filled with water, which evaporates over the course of the journey as air is blown across it, resulting in a much cooler interior. This, of course, relies on the car being in motion (which is not always possible in a busy city) and, as my wife learnt, can result in one side of your face becoming pretty numb after a long, fast drive.

The car and I have since parted company. I quickly realised that true happiness would never burn money so quickly, and I soon tired of ending journeys with more oil on me than in the engine. The swamp cooler however, and its simple process of evaporative cooling, fascinated me enough to explore the history of evaporation further.

If you look back through history, and even at nature, you can see many examples where the evaporation of water has been used as a cooling mechanism. The Romans and Egyptians would cool tents by hanging large wet sheets in the doorway, miners in the desert would cover boxes of food with wet burlap, trees interact with the environment by transpiring water through pores in their leaves, and even you and I cool ourselves through evaporation each time we perspire.

Today, evaporation is used extensively to cool everything from entire buildings to kegs of beer. What drives our desire to make use of this process is its high level of efficiency. If we use the beer keg as our example, I would need approximately seven times the amount of water moving from a solid (frozen) to liquid state to cool the beer as I would need if moving the water from its liquid to vapour state.

If we consider the process of evaporation of water in the context of our industry, and more specifically the temperaturecontrolled distribution of pharmaceutical products, it is here that we can see some significant benefits when compared with the more passé approach of using the process of melting.

The numbers alone show that it takes 334kj/kg to take water through the melting phase, which as I mentioned previously is increased by almost seven times to 2,260kj/kg when moving through the evaporation phase. However, using this very efficient process to maintain pharmaceutical products within a range of 2°C to 8°C is where the challenge really lies.

It is at this juncture that we need to look at how we can move the point at which evaporation occurs, and the most logical process is to lower pressure. A good way to think of this (as I am often told by the people who choose to risk life and limb climbing mountains) is to look at the boiling point of water at altitude. If you were to climb Mount Everest, for example, the boiling point of water is nearer to 70°C than it is to 100°C. This example shows that a high performance cooling process is a genuine possibility if the correct pressure can be created.

But what advantage can it bring beyond increased cooling capability? Let’s look at the benefits individually and relate them to today’s temperature-controlled packaging world.

PRECONDITIONING

The task of lowering the temperature of cooling elements prior to their assembly into temperature-controlled packaging may need to be done 10 to 15 days in advance of shipment in order to ensure that the parts have fully reached their optimum temperature.

This stage is critical when working with materials that are required to melt, but presents quite the logistical burden, as well as opening up some of the first risks related to the final quality of the packed solution – risks related to errors such as incorrect fridge/freezer set point, damage during loading, unloading and of course, machine failure. Further, there is a need to consider the environmental impact of running this equipment. Europe alone generates 60 million tonnes of CO2 each year from fridges and freezers.

An evaporative process driven by a pressure change removes the need for preconditioning, and devices such as this can start at the press of a button.

SIZE

With great power comes great efficiency, and this is also true when we consider the size of a system using evaporation. If applied correctly, a system that uses evaporation rather than melting can hold the same volume of payload but offers a reduction in the overall system size by up to 40 per cent. This is a great advantage when we consider that traditional temperature-controlled solutions have, in some situations, only been able to offer five per cent payload space in relation to total system size. This benefit becomes even greater when you start to combine evaporation with more cutting edge insulation, such as vacuum insulation – a material that at 25mm offers the same thermal protection as 100mm of expanded polystyrene.

RISK REDUCTION

This is something I touched on earlier but it is worth expanding upon. If we walk through the process of packing up and shipping a temperature-controlled solution, we are presented with numerous risks, many of which happen in environments outside of our site and control.

Like most things, the highest risk area is right at home, and this is no different in the world of temperature-controlled packaging. In addition to preconditioning, there is also a risk of the system being packed in the wrong order or for the wrong season, or placing the packed solution into a 5°C environment while it waits to be picked up. This last example poses a threat to a solution designed to work in an environment above 5°C.

In addition to ‘at home’ risks, numerous factors can lead to system failure and product excursion. These can be as simple as a delay in shipment, extended exposure times on hot runway tarmac, and unplanned storage in cold rooms at transport hubs. Customs interference might result in having to disassemble the product for x-ray, which could potentially be followed by the incorrect reassembly of component parts. In some more extreme cases, I have heard of holes being drilled into boxes as a way to take internal air readings.

As a safeguard, coupling an evaporative cooling system with a thermostatic control device will allow the thermostat to regulate the temperature within. If placed in a refrigerator, the thermostat will close and the process of heat absorption will almost cease, placing the system in a hibernation-like state and resulting in no further drop in temperature below that of the refrigerator’s set point.

Equally, a system working with evaporative cooling would be a sealed unit. There would be no extra parts to load in the correct order meaning that at customs, the chance of incorrect reassembly is eliminated. I am afraid however that even an evaporative system would not be able to withstand the drill.

CONCLUSION

Although evaporative cooling is not the newest of ideas, the application of this method within the world of temperaturecontrolled packaging is a significant step, offering a huge improvement in product protection and an overall reduction in the costs to move a product. It may not replace conventional solutions overnight, but this technology is already having an impact on the market. Whether we look to consider the growing need to ship for longer durations, to more hostile climates or at reduced freight costs, it is for these issues that a solution that uses evaporative cooling truly supersedes the systems of today.


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Richard Harrop is the Product Development Manager of SCA Cool Logistics and has been involved in the temperature control packaging industry for six years, initially in packaging design and then moving into the commercial field. Qualified in structural packaging design, Richard previously worked as technical designer for the FMC sector before moving into the world of temperature-controlled packaging, where he has worked predominately within packaging technology. He has developed and implemented several successful temperature-controlled solutions for many of the world’s leading pharmaceutical and biotech corporations.
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