Heat transfer and performance enhancement investigation of biomimetic honeycomb gas coolers in transcritical CO₂ heat pumps

CO₂ air source heat pump heating technology has characteristics of strong adaptability to outdoor temperature in cold areas and high outlet temperature, which is widely used in heating and domestic hot water supply. A gas cooler is one of the crucial components in CO2 heat pump systems, while its performance and different structural forms will directly affect the performance of the whole CO2 heat pump system. In order to improve its heat transfer efficiency, a biomimetic honeycomb gas cooler is proposed in this paper, the steady-state simulation model of the biomimetic honeycomb gas cooler is established, and the reliability of the model is verified by experimental data. In addition, the effect of structural parameters and operating parameters on the heat transfer performance is studied, also the heat transfer performance of the biomimetic honeycomb gas cooler is compared with that of the internal spiral tube gas cooler and triple tube-in-tube gas cooler. The results show that the performance of the biomimetic honeycomb gas cooler can be effectively improved by reducing the water flow rate. Under the same working condition, the performance evaluation criteria¹ of the 1st, 2nd and 3rd layer biomimetic honeycomb gas cooler s are about 193.4%, 239.9% and 357.0% higher than that of the internal spiral tube gas cooler, and about 197.2%, 205.9% and 237.7% higher than that of triple tube-in-tube gas cooler. This research is helpful to provide the reference for the design and optimization of this type of gas cooler and is conducive to the popularization and application of CO₂ air source heat pumps.