The effect of software version on the rate of temperature pulldown in Starcare banana shipments

Summary

This report covers a series of climate chamber tests addressing the question why software version 0349_07 yields faster temperature pulldown in Starcare CA shipments of bananas than software version 035l_23. On beforehand three possible reasons were postulated: 1. Change in evaporator fan speed control. 2. Change in maximum refrigeration capacity. 3. Change in supply air temperature distribution across the width of the container. A series of 20 tests was ran in the period from 11-04-2017 till 23-04-2017. During all tests 56 temperature sensors (PT100) recorded temperatures at a one minute interval. In principle each test was only terminated after all temperatures had been in steady state for at least four hours. Based on the results it is concluded that: 1. There indeed is a change in evaporator fan speed control. This may explain a difference in temperature pulldown occurring in the later stages of the pulldown, after Treturn reduces below Tsupply + 1.2 °C. 2. There seems to be a change in maximum refrigeration capacity, which could explain the difference in temperature pulldown. It is not believed this difference has much impact on the rate of temperature pulldown in banana shipments, because usually in those shipments the unit hardly needs to call upon the maximum refrigeration capacity. 3. The software version does not affect the supply air temperature distribution across the width of the container. To find out which effect is strongest, the difference in evaporator fan speed control or the reduction in maximum refrigeration capacity, it is recommended to perform a ‘big data’ analysis on numerous Starcare CA downloads (RCM data) of software 0349_07 and later software versions.