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Integrated waste heat recovery from converter valves using a vapor-compression heat pump and single-effect LiBr absorption chiller
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DOI：10.3389/fenrg.2026.1835257.png)
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Abstract
En 中文
Converter valves in ultra-high-voltage direct current (UHVDC) converter stations continuously release megawatt-level low-grade waste heat; which is typically rejected through cooling towers; resulting in energy loss and substantial auxiliary electricity consumption for valve-hall air conditioning. This study develops a cascade waste-heat utilization system in which converter-valve waste heat is upgraded by a vapor-compression heat pump (VCHP) and subsequently used to drive a single-effect LiBr–H2O absorption refrigeration (AR) subsystem for chilled-water production. A coupled thermodynamic model is established for the cooling-water loop; VCHP cycle; AR cycle; and solution heat exchanger (SHX); with explicit temperature–pressure–concentration closure and crystallization-avoidance constraints. Under representative 24 h operating disturbances; the VCHP evaporator absorbs 3.88 MW of waste heat; the condenser delivers 5.13 MW of upgraded heat; and the compressor consumes 1.25 MW; resulting in a mean heating coefficient of performance; (COPHP); of 4.10. The AR subsystem provides 2.0 MW of chilled-water capacity with a mean COPAR of 0.74; while the corresponding cooling-only COPsys is 0.56. The strong-solution SHX outlet temperature remains within 51.3–54.9 °C; indicating crystallization-safe operation. Compared with a baseline configuration that rejects waste heat through cooling towers and satisfies cooling demand using electrically driven chillers; the proposed system improves normalized integrated performance by approximately 40% across winter; summer; and transition scenarios. The results demonstrate the thermodynamic feasibility of the proposed VCHP–AR cascade under the modeled operating conditions and indicate its potential to improve energy utilization in UHVDC converter stations.
Keywords:
waste heat recovery
converter valve
crystallization-safe operation
LiBr absorption chiller
normalized integrated performance
vapor-compression heat pump
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