# Approaching optimum COP by refrigerant charge management in transcritical CO2 heat pump water heater

> Research article (International Journal of Refrigeration, 2020) · cited 21× · AI/ML

**Wikidata**: [openalex:W3036712365](https://www.wikidata.org/wiki/openalex:W3036712365)  
**Source**: https://4ort.xyz/entity/approaching-optimum-cop-by-refrigerant-charge-management-in-transcritical-co2-heat-pump-water-heater