While the visible plume from a cooling tower is not a pollutant, it can affect the surrounding environment. Moreover, the accompanied evaporation loss has a great potential for wastewater recovery. In the present study, a novel coupling technology for water conservation and plume abatement was proposed, and its feasibility was verified by using thermodynamic analysis. A surface-type heat exchanger was designed and a thermodynamic calculation model was established. Next, based on the principle of “no plume,” the effect of the number of heat exchanger units (N) and the circulating water volume (G) on the water conservation and plume abatement was evaluated under design condition. Results showed that the optimized parameters for the operation of the cooling towers were N = 8 and G < 3000 m³/h, which have a good effect on water conservation and plume abatement. Furthermore, as per the condensation calculation model, the average water conservation amount was 1.105 kg/s and the annual water conservation amount reached 2.8641 × 10⁷ kg.

Experimental investigations on the heat transfer performance of supercritical water flowing in the subchannel of supercritical water-cooled reactor (SCWR) simulated by a triangular channel were conducted at pressures of 23–28 MPa, mass flow rates of 700–1300 kg·m⁻²·s⁻¹, and inner wall surface heat fluxes of 200–600 kW·m⁻². An 8 mm diameter fuel rod with a 1.4 pitch to diameter ratio was used. The effects of pressure, mass flow rate, and heat flux on the heat transfer performance under the resistance of a standard grid spacer were analyzed. Experimental results showed the significant positive influence of the grid spacer on the supercritical water in the subchannel. Moreover, in the presence of the grid spacer, the parameters influenced the heat transfer with different degrees of strengthening reaction. In view of the phenomenon in the tests, the rule of the supercritical heat transfer was further revealed by the comparison between empirical formulas and experimental data. This paper mainly studied the positioning grid function and the fluid flow characteristics downstream of the subchannel under the influence of the standard grid spacer and the impact mechanism of each parameter on the whole heat transfer process coefficient.

The pressure drop characteristics of subcooled water were experimentally investigated in a circular cooling channel with and without a twisted tape (TT) under high heat fluxes, which was designed for the water-cooling structure of the divertor target in a tokamak device. The working medium was deionized water, and the main parameters were mass flux G = 3000–8000 kg·m⁻²·s⁻¹, inlet pressure of the test section p = 3, 4.2, 5 MPa, equivalent one-side heating flux q_e = 5~10 MW·m⁻². The off-center circular channel is electrically heated to simulate the unilateral radiation heating on the divertor target by high-temperature plasma. The pressure drop experiment of vertical upward circular cooling channels under high and unilateral heat flux is carried out. The influences of the TT and system parameters such as q_e, G, and p on the pressure drop of the test section (Δp) were discussed in detail. In the single-phase (SP) flow region, Δp is mainly affected by the TT, G, and q_e. The pressure drop with a TT is significantly higher than that without a TT, a higher G and a lower q_e lead to a greater Δp. In the subcooled boiling (SB) flow region, Δp is correlated with the TT, q_e, G, and p: the influence of the TT and G decreases, while the influence of p increases. The higher the q_e, the higher the G, and the lower the p, the larger the Δp. The results show that almost all of the SP pressure drop correlations for heated circular channels overestimate the experimental pressure drop coefficient ratio for a given viscosity ratio. According to the test results, a new correlation of SP pressure drop under high and unilateral heat fluxes has been proposed, the average error (AE) and root mean square error (RMSE) of which are 0.26% and 3.17%, respectively.

To study the pressure drop characteristics of hypervapotron, which was designed as a water-cooling structure in the divertor dome of the fusion reactor, the pressure drop tests of subcooled water were carried out in a vertically upward hypervapotron. To simulate the one-side radiant heating condition in the engineering application, the non-uniform heat fluxes were obtained by using the off-center electrically heating method. The system parameters were as follows: mass flux G = 2000–5000 kg·m⁻²·s⁻¹, inlet pressure p = 2–4 MPa, and equivalent one-side radiating heat flux q_e = 0–5 MW·m⁻². The effects of the parameters on the pressure drop were discussed in detail. It was observed that in the single-phase (SP) region, the pressure drop was little influenced by the inlet fluid temperature (T_b,in). However, in the subcooled boiling region, the pressure drop increased rapidly with the increasing T_b,in. A higher G leads to a high pressure drop. In the SP region, the influence of p on the pressure drop is not obvious, and the pressure drop decreased with the increasing q_e. The test data are used to evaluate the typical pressure drop correlation, and the results show that none of these correlations can predict the pressure drop well under the test conditions. Therefore, a new pressure drop correlation is proposed for subcooled water in a hypervapotron under high and non-uniform heat fluxes. The new correlation has a high prediction accuracy for the test data, and the mean relative error (MRE) and root mean square error (RMSE) are 0.72% and 4.33%, respectively. The test results have a reference value for the design of the water-cooling structure of the diverter.