This article discusses how heat pumps can extract heat from sources like air and water to provide heating. Researchers aimed to reduce the complexity and cost of heat pumps by investigating ways to minimize the amount of refrigerant used while maintaining performance. They studied different compressor lubrications, tested compact heat exchangers, and created new mini-channel heat exchangers. The findings show that using these mini-channel heat exchangers can help reduce the refrigerant needed in a small-capacity heat pump without sacrificing efficiency. This innovation could make heat pumps more competitive and environmentally friendly alternatives to traditional heating systems.