Hygrothermal absorption and desorption of deep underground hydropower station envelopes

The heat and moisture environment of hydropower stations underground plants will directly affect the useful life and safe running of electromechanical devices. Engineers need to calculate the transient heat and moisture loads due to the storage and transport of heat and moisture in the porous cavern envelopes. In order to avoid complex dynamic calculations and save design time, this paper gives monthly mean hygrothermal absorption and desorption indexes and regression formulas of limestone envelopes with no-lining. These indexes are obtained by means of numerical calculation method based on the air temperature and moisture fluctuation ranges controlled by air-conditioning systems and hygrothermal parameters of cavern envelop. And then, validity and reliability of hygrothermal absorption and desorption indexes are verified by using monitored data of main plants in Dachaoshan and Jiangkou hydropower stations in China. The results show that the heat and moisture indexes can be applied in real project design and operation management.

Research highlights
► Hygrothermal effect of cavern envelopes of deep underground hydropower stations is simulated.
► The hygrothermal effect is mainly due to indoor air temperature and moisture fluctuations.
► The monthly hygrothermal absorption and desorption indexes and regression formulas are provided.
► The indexes can be applied in practical engineering design and operation management.