SEARCH Articles Figures Tables CO2 as a Working Fluid for Heat Pump Systems Closed-loop heat pump systems Coupling Reactions and Chemical Heat Pump System Heat pump Heat pumping Heat pumps hybrid systems using Heat pumps system using Heat systems Heating heat pumps Heating systems/heat pumps Heating systems/heat pumps Hybrid heat pump systems Open-loop heat pump systems Pump systems Pump, pumping system Pumping heat pump systems Pumping heat pump systems Pumping systems