A Heat Pump Dual Temperature Display Cabinet Using Natural Refrigerants

•A dual-temperature display cabinet was developed to harvest condensing heat.•R744 is more efficient than R290 when ambient temperature is lower than 20 °C.•R744 prefers gas coolers with double tube banks of R290 condensers.•R290/R600 mixture is more efficient than R290, R744, and R600 at any temperature.•R290/R600 mixture can be a drop-in replacement for R290 in heat-recovery DTODCs.