AQUEOUS SODIUM HYDROXIDE SEASONAL THERMAL ENERGY STORAGE

摘要

Seasonal storage of sensible thermal energy in materials is a challenge in respect to thermal lossrncorresponding to low volumetric energy density. In a process involving absorption and desorptionrnlower heat losses and higher energy densities can be reached. The working pair sodium hydroxidern(NaOH) and water can be employed to this purpose. A possible application of such a system can be arnsingle family passive energy building that requires a maximum power output of approximately 8 kW.rnThe required absorption/desorption zone can be designed as a falling film tube bundle, using eitherrnHu’s or Owens’ correlations. To meet the required power the tube bundle can be built of 300 mm longrntubes with an outer diameter of 12 mm in a configuration of either 3 rows of 18 tubes or 2 rows of 25rntubes. During desorption one row of 18 tubes or 3 rows of 6 tubes are sufficient. In the absorption orrndischarging process a mass flow of 2 to 4 kg/h of aqueous NaOH with a concentration of 50 wt%rnNaOH is required. In the reverse process 18 to 30 kg/h of aqueous NaOH at a concentration of 30 wt%rnare necessary. The mass transport is performed without recirculation, reducing the parasitic powerrnconsumption. Initial experiments conducted with a less reactive substitute liquid showed goodrnhomogeneous distribution.