| Abstract [eng] |
In this paper, eutectic transport refrigeration system with R290 (propane) is analyzed. In eutectic refrigeration systems phase-change material (eutectic liquid) is used to absorb heat from the refrigerated compartment. Due to the fact that propane has almost no global warming potential and no ozone depletion potential, it is held in high regard when the ever more demanding environmental requirements are considered. On the other hand, propane and other hydrocarbon refrigerants are flammable and considered to be class A3 refrigerants. For this reason, additional requirements and safety regulations are put into effect which mainly limit the allowed refrigerant charge in the system. According to IEC 60335-2-89, the maximum allowed hydrocarbon refrigerant charge in a commercial refrigeration system currently is 150g, though this limit is expected to rise to 500g soon. The main aim of the calculations provided in this paper is to determine whether the analyzed transport propane refrigeration system can meet these requirements. To achieve this, a mathematical model for two- phase flow with Premoli correlation for slip ratio was used. The results showed that regardless of ambient temperature, the charge in the system exceeds the 500g limit and is close to 750g. As an alternative to propane, propylene was also analyzed – results were similar to propane. This means that these systems need further charge optimization. In addition to charge calculations, experiments to determine pull-down times and energy consumption were also carried out. The results showed, that the propane system can perform a pull-down from −20°C to −33°C in 4.5 hours and consume almost 6 kWh of electricity (when the ambient temperature is equal to 20°C). |
