Experimental Dataset for Rapid Monitoring of Concentration and Scaling Tendency in Recirculating Cooling Water Using Paper-Based Colorimetric Tests

Recirculating cooling systems require reliable control of water concentration to limit scaling while avoiding unnecessary water losses associated with excessive blowdown and make-up water demand. This study developed and evaluated a paper-based colorimetric approach for rapid monitoring of concentration and scaling conditions in recirculating cooling water. The experimental validation was performed using make-up water from the cooling-water system of the Rivne Nuclear Power Plant and a laboratory-scale installation simulating progressive water concentration by controlled evaporation. Test A was used for chloride determination and subsequent calculation of the concentration factor (CF), whereas Test B was used for total hardness (TH) determination. The proposed measurements were validated against ISO 9297 and ISO 6059, respectively, and the concentration–hardness precipitation index (CPI) was calculated from the expected and measured TH values. In addition, the Langelier Saturation Index (LSI) and Ryznar Stability Index (RSI) were calculated to provide complementary scaling assessments. The colorimetric tests showed strong agreement with the reference methods, with Pearson correlation coefficients of 0.996 for Cl−, 0.997 for TH, and 0.9996 for CF (p < 0.0001). CPI, LSI, and RSI showed a consistent shift towards increasing scaling tendency with increasing CF. The proposed approach therefore provides a simple screening tool for operational control of recirculating cooling water and may support more efficient water use and circular water management.