3. Low Evaporation Temperature Absorption Heat Pump

Three novel heating systems based on low evaporation temperature absorption heat pumps (AHPs) were proposed with an improved primary energy efficiency and reduced pollutant emissions in comparison to the conventional fuel-based heating systems. The ASAHP can be configurated as direct air source, indirect air source, spay-type air source and energy-tower air source systems, whereas the GSAHP can be configurated as buried-borehole and underground-water systems. The performance characteristics of NH₃/H₂O ASAHP under various driving source temperatures, ambient air temperatures, and produced hot water temperatures were simulated. A prototype of the low evaporation temperature AHP using NH₃/H₂O was developed to validate the energy-saving potential. Experimental investigations were conducted under standard conditions, different off-design conditions, and different adjusting methods. In addition, a comparative analysis of the heating performance (first-law and second-law of thermodynamics) and emission characteristics (CO₂ and NO_x) of the proposed heating systems to existing heating systems was conducted to determine the benefits of the modifications.