Thermal performance enhancement of a heat exchanger using metal chain as a novel turbulator

Enhancing heat transfer in a heat exchanger system is critical to many industrial applications. There are many problems that require in-depth studies to find solutions. One of the main problems is the poor heat transfer rate, due to the fluid flow behavior inside the tubes, and to increase the heat transfer rate, the flow behavior inside the heat exchanger tubes must be changed. This study presents an experimental and numerical approach to enhance heat transfer in a heat exchanger tube using new types of turbulator (metal chains) inserted in the heat exchanger tube to change the flow behavior. Fifteen (15) configurations of metal chains were tested; three ratios of the wire diameter/tube diameter, (t/D = 0.1, 0.15 and 0.2), with five lengths of the chainrings represented by the ring length/tube diameter, (P/D = 1, 2, 3, 4 and 5). The experimental system (test rig) consisted of a 2000 mm thermal insulated carbon steel tube exchanger test section, in which the inner and outer diameters were 20 mm and 26 mm respectively. The fluid used was heavy fuel oil, with a fully developed turbulent flow, Reynolds number, (Re = 5000 to 15000), and uniform heat flux on the external wall of 6000-Watt. A 3D computational fluid dynamics calculation was also made to study the effect of metal chains on the fluid flow behavior inside the tubes on the overall thermal performance. Both experimental and simulation results showed that the insertion of the metal chain into the heat exchanger tube increases the thermal performance factor (η), the Nusselt number (Nu), and the friction factor (f). The thermal performance factor (η) decreased with the increase in Reynolds number for all cases. The highest thermal performance factor (η) was found at t/D = 0.15 and P/D = 3, while both the highest Nusselt number (Nu) and friction factor (f) were found at t/D = 0.2 and t/D = 1. The numerical study unveiled that the use of metal chains inside the tube leads to path changes and splits in the fluid flow. It is crucial to generate large longitudinal and transverse vortices inside the tube. These vortices play a substantial role in enhancing heat transfer

Improvement of the operation and safety of nuclear power plants

This study investigated the importance of heating processes within a nuclear power plant. The application of Fourier’s law of heat conduction enables determining temperature distributions within the nuclear fuel rods. In contrast, convective cooling occurs on the road surface. The coolant, cladding, and fuel temperature distributions through a reactor are determined. In addition to heat transfer in the reactor core, some power plants engage heat exchangers to produce steam that is fed to a turbine-generator to produce electricity. Thermal power plants reject condenser heat to the environment through mechanisms such as cooling towers as according to a consequence of the second law of thermodynamics. These investigations provide a possible modeling approach and load the following control strategies for problematic nuclear power plants to provide an assessment of the concept designs. A load frequency control strategy and average temperature control mechanism are studied to get load following nuclear power plants. This study reports on the development and analysis of some novel versions and approximations of the fractional-order (FO) point reactor kinetics model for a nuclear reactor with slab geometry. These models evolve from the FO point reactor kinetics model, which has been derived from the FO Neutron Telegraph Equation for the neutron transport considering the subdiffusive neutron transport. This study also proposes a water level control system for a nuclear steam generator (SG). The control system consists of a feedback controller and a feedforward controller. The feedback controller comprised in the first order, the feedforward controller is of second order, and parameters of the two controllers are linked with the parameters of plant model; thus scheduling is easily implemented in practice. A model was developed for the thermal analysis of closed feedwater heaters in which wet steam is extracted from the steam turbine (and piped into the heater). Application of this model is of relevance to nuclear power plant diagnostics where the fluid flowing through the steam turbine is wet steam