Granted Patent EP4281714 : A Feasible Architecture for Direct Warm Liquid Subcooling Defrost in Air-Source Heat Pumps

**NOTICE: This version contains errors in the data/text. Please refer to the latest version for the correct information The invention establishes the technical feasibility of the Direct Warm Liquid Subcooling Defrost approach to eliminate defrost-related inefficiencies in air-source heat pumps. It recovers the unutilized thermal energy inherently present in the warm condensed liquid refrigerant by routing the flow directly to a selected evaporator section targeted for defrosting, while the remaining parallel sections continue operating in standard evaporation mode. In the streamlined patented embodiment, this architecture significantly reduces defrost-specific energy consumption. In the advanced ejector-based embodiment, defrost inefficiencies are effectively eliminated by enabling the compressor suction pressure to correspond to the higher evaporating pressure of the non-defrosting sections, which operate at different evaporation pressures due to unequal frost accumulation. In future implementations, the ejector may be replaced by an expander, enabling further optimization of overall system efficiency.