空气源跨临界CO₂热泵中回热器影响的研究

The impact of the internal heat exchanger (IHX) on a transcritical CO₂ heat pump is investigated based on both theoretical and experimental methods. A thermodynamic analysis is conducted to study the influences of the IHX’s heat transfer efficiency at different gas cooler outlet temperatures and discharge pressures. The theoretical results show that whether the IHX improves the system performance coefficient depends on the gas cooler outlet temperature. Experiments are performed on a transcritical CO₂ heat pump prototype, and the results indicate that IHX can reduce the optimal discharge pressure, and the degree of this reduction is enhanced with the decrease of ambient temperature and the increase of inlet and outlet water temperatures. Applying IHX brings an increase of 6.65％ in the coefficient of performance and a decrease of 6.22％ in power consumption at most, but it leads to a higher compressor discharge temperature, hence it must be restricted at lower ambient temperature. Moreover, the differences between theoretical and experimental results are analysed, and a numerical correlation of the reduced value of optimal discharge pressure with the ambient temperature, inlet and outlet water temperatures is established based on the experimental data.