[I am a little confused by your remark: 'the product (which has internal temperature controls) at say 5 degrees'. Using the averaging of 'rate' to get the MKT, instead of just the temperature, has been found to correlate better with shelf-life studies, so is preferred in some industries. Alternately if you have a list of temperatures pulled at various times (hourly, every 15 mins, etc) you could compile them and calculate the 'rate constant' for each period and then average, take natural log and get the 'effective temp' (MKT) Yes, a transit time for each period (all in the same unit) will work. If I understand what you have said above would it be more meaningful to add transit times to my waypoints, for example collection at origin to export gateway 5 hours at 20 degress, Flight to import gateway 12 hours at (a guess because I cannot find any cabin temperature at the moment) 25 degress, 5 hours to clear and deliver at say 25 degrees and the product (which has internal temperature controls) at say 5 degrees. I just posted a reply and it has gone the same thing happened the other day, so maybe 2 will turn up (like buses) The equation is a little misleading in that it assumes equal time periods, but it is easier to calculate with weighted periods when you have sections of time time intervals (like the egg example). Sdckapr wrote:Does this help? Your example does not give what Activation energy they used, It appears to be about 83.14 so I assumed 83.11472 so it was related to the gas constant. You need to enter times for each period to calculate the MKT, otherwise you are indicating that it just spent 48 hours at one temperature and then you don't need the to average at all. I put the numbers from your workbook example, but it only lists the time at origin (48 hours) so the MKT is the origin temp. I included the range of temperatures (with a range of kinetic energies) and also show the calculation for the weighted mean temperature which is much lower than the MKT in this example. this makes it easier to calculate if you have periods of different duration. The attached shows the cals for the egg example as individual 7 time units (7 hours) and the weighted scheme 2, 4,1 hours. Does this help? Your example does not give what Activation energy they used, It appears to be about 83.14 so I assumed 83.11472 so it was related to the gas constant.

Mkt calculation spreadsheet