Case Studies in Thermal Engineering (Nov 2024)
Performance evaluation and optimization guidance for steam generating heat pumps with significant temperature lift
Abstract
Steam generating heat pumps (SGHPs) offer a promising alternative to coal-fired boilers. To address the lack of general optimization strategy of autocascade SGHP (ASGHP) for variable operating conditions and variable cycle configurations, this paper models an ASGHP with the addition of an IHX and the use of steam injection instead of the injector whose performance is more sensitive under variable operating conditions. The general optimization strategy of ASGHP was analyzed and proposed using the advanced exergy analysis method to evaluate the feasibility and reliability of the system under the significant temperature lift condition comprehensively. Subsequently, an optimization analysis of the system was conducted in accordance with the proposed strategy. The results indicate that the ASGHP efficiently uses a low-temperature heat source (10–20 °C) to generate high-temperature steam, achieving a substantial temperature increase and notably lowering the compressor discharge temperature. The optimization sequence for ASGHP involves prioritizing the compressor, evaporator, and condenser in that order. The average steam mass flow rate increases by 3.2 % when the evaporator heat transfer efficiency rises by 10 % at a heat source temperature of 20 °C. Furthermore, a 5 % increase in the condenser heat transfer area results in a 4.1 % increase in the average steam mass flow rate. These results can provide theoretical guidance for the design and optimization of ASGHPs.
