Flexible heat pump or chiller with hybrid water/LiBr absorption/compression cycle

摘要

The concept and general considerations for the design of a hybrid absorption/compression cycle are presented. An electrically driven high-speed turbo compressor which is directly integrated in a single-stage water/LiBr absorption heat pump cycle provides a pressure lift for the refrigerant vapor transmitted from the evaporator to the absorber or from the desorber to the condenser, resulting in increased flexibility of the cycle for operation under non-standard boundary conditions. By detailed steady-state thermodynamic process simulation, three main operation modes are investigated concerning the required temperature level of the cooling water and the driving heat source as well as the increase of the chilled water capacity. Characteristic data for compression ratios between 1 and 3 are presented. Depending on the specific electrical input a significant change of the operating limits is observed. In order to assess the influence on the overall system efficiency, selected key figures such as driving power of the compressor, temperature lift, driving heat temperature level, as well as thermal and mechanical COP, are determined and discussed.