The topic of the effectiveness of styro shippers (heat only) comes up occassionally on the MB, but there has been no hard data – until now. I cobbled together a Particle Photon wifi dev module with a couple of temp sensors, a standard DHT22 sensor for air temp and a DS18B20 waterproof temperature probe for liquid temperature. Here is a graph of the results:
The experiments were carried out in my garage during the first heatwave of the summer.
The first part of the chart shows the bottle in open air, clearly showing the bottle temp closely following the ambient temp. With this as a baseline, I cooled the bottle (filled with water) to 63F and placed in in the styro shipper in its shipping box. As you can see, it does a pretty good job until the air temp climbs into the nineties. I think this shows that styro shippers are very effective unless it is extremely hot, but you can draw your own conclusions.
Paul, thanks for the input. I would love to see the same thing with a pulp cardboard shipper.
From the pictures, it looks as if you did not have the styro in a cardboard shell, which would add another buffer against ambient temperature swings. Also if the bottle was chilled to 55 degrees or so, the way a winery might ship, it would probably have a lower peak temp during a 2-3 day transit.
Charlie, if it starts at 63 and peaks at 83 after 3 days in the ambient 90’s, I would guess that starting at 55 might keep the peak well under 80. Sure, it won’t make any difference after a week or more, but for short term shipping, it sure can’t hurt.
Very nice data, but the second (right) half of the data doesn’t make sense to me.
Let’s look at the part where the top & bottom temps are stabilized.
Why is it that the liquid warms up by about 3-4 degrees when the temperature differential is over 20 degrees, and then cools down over about the same time period by 4-5 degrees but with a temp differential of only 5-6 degrees? What is it that makes it easier to cool down as opposed to warm up? Inside the styro shipper the heat transfer up or down should be the same, no?
5 to 8 years ago, Leslie Fisher did some experiments with putting some kind of temperature tracking device in a styro case and shipping it by plane. I do not remember the details but it would be good to have both sets of data. IIRC, her results showed that with a normal plane flight the risks were minimal.
Great work, by the way. I always love it when someone actually checks data instead of just speculation. What I find interesting is that the lag between outside peak and bottle peak seems to be about 8 hours, after which the styro actually keeps things warmer until the next daily cycle.
Interestingly enough, Shawnda and I are about to do an experiment in a similar fashion, but to determine which material is ‘superior’ - Styrofoam vs. corrugated cardboard as an insert - for The Wine Check. We don’t have as accurate of equipment, by a long shot, but when we have the comparisons we’ll definitely post here on this same thread as another data point.
Let me preface this with it has been many years since I took thermodynamics in college so counting on my memory is risky. I agree that starting for a lower bottle temperature won’t hurt but I don’t think it is going to make much difference after the first day for a single bottle in a case shipper. The lower the starting temperature of the bottle the greater the delta T between the bottle and the air in the styro shipper and this should probably stabilize close to the same temperature that the 63F bottle did before the ambient temperature impacts the air temperature in the shipper and then from there everything would be the same. Changing the thermal mass from one bottle to twelve should have a more drastic impact and would probably keep the peaks lower due to the greater energy required to raise the temperature of the greater mass. Of course, a full shipper starting at 55 would be the best.