Performance investigation of a solar-steam dual-source driven double-effect absorption heat pump for coal slime drying

The application of solar-driven absorption heat pumps in the industrial heating field has long been limited by the intermittency and instability of solar energy. To address these challenges, this paper constructs a dual-heat-source double-effect lithium bromide absorption heat pump system integration scheme driven complementarily by solar thermal and industrial steam, and builds a simulation model based on the Aspen Plus platform (validation error < 1.13%). Research shows: under the drive of 230 °C rated heat transfer oil, the system has a reasonable dilute solution inlet concentration of 58%; as the solar thermal contribution ratio increases from 50% to 90%, the expansion of the solution concentration lift and the decrease of the circulation ratio prompt the system coefficient of performance (COP) to steadily increase from 2.05 to 2.31. To mitigate the impact of the all-weather solar irradiation fluctuations, this paper proposes and verifies a "solar thermal first, steam peak-shaving" heat pump system solar thermal ratio regulation strategy with a 10% steam heating lower limit. 24-hour simulation shows that this strategy constrains the process hot air temperature between 61.2 and 66 °C, and the all-day average COP stabilizes at 2.12. Environmental and economic benefit evaluation confirms that, compared to the baseline scheme with a fixed 50% steam ratio, this strategy, under the premise of not increasing extra hardware investment, can net save 50184 MJ of steam daily, which translates to an annual comprehensive operating expense (OPEX) reduction of approximately 1.3952 million yuan, and reducing 1714.62 tons of carbon dioxide emissions. This study clarifies the thermodynamic mechanism of the cascade coupling of dual heat sources, and provides a theoretical basis for industrial heating systems to efficiently and stably consume renewable energy.