Practical thermal resistance and ice requirement calculations for insulating packages

Several styles of insulating packages were studied, ranging in size from 0.5 to 5 cubic feet and varying in construction from the ordinary expanded polystyrene cooler to various liner-in-box arrangements with and without aluminium foil surfaces. Ice-melt tests were conducted to measure package insulating ability and the results were used to determine the thermal resistance (R-value). The R-value was then related to details connected with package construction including wall thickness, number of layers and number of foil surfaces through a simple equation so that it can be estimated for any construction. The system R-value can then be used to estimate refrigerant requirements and temperature holding times for known shipping environments. Examples are included. Copyright © 1999 John Wiley & Sons, Ltd.