Relevance of external factors in choosing a special vehicle for the perishable freight conveyance

Abstract

Introduction. The new Rules for the perishable freight conveyance have changed the structure of freight flows towards higher volumes of transportation in special isothermal vehicles. When choosing them, the shipper should know the estimated period of transportation of perishable food, where the temperature of the latter would remain within the range of established transportation and storage temperatures.Materials and methods. The calculation of the permissible transportation period uses the overall heat transfer coefficient of the body of a special vehicle determined by thermal tests using internal heating or cooling methods with mathematical dependencies that factor in the calculated change in the heat transfer coefficient during movement in train set.Results. The authors calculated the permissible transportation period of bottled beer in a special isothermal vehicle in summer for permissible storage temperatures of perishable food from 0 to 10 °C in the range of average train speeds from 0 to 120 km/h. The calculation results show that the permissible transportation time with the heat transfer coefficient obtained in thermal tests amounted to 69.4 hours, and the calculation using external factors showed 57.1 hours, i. e. decreased by 12.3 hours, or approximately 18 %.Discussion and conclusion. The permissible period of perishable freight conveyance in special isothermal vehicles depends on the average transportation speed and the infiltration of outside air and solar radiation into the vehicle. The shipper should consider these circumstances while selecting the parameters of special vehicles in order to prevent food fromdeterioration or spoilage.

Keywords

• perishable freight conveyance
• special vehicle
• overall heat transfer coefficient
• thermal insulation
• heat-enclosing structures
• heat emission coefficient
• infiltration
• permissible transportation period