Abhijeet Mohan Vaidya

Steady State and Transient Characteristics of Natural Circulation Loop

A natural circulation loop (NCL) consists of a heat source at lower elevation, heat sink at higher elevation and connecting piping. It is representative of primary heat transport system of a nuclear reactor or a solar power plant. The study of steady state and transient characteristics of the NCL is hence important. In this work, a 1D simulation code is developed to model the NCL. The effect of heater power on steady state mass flow rate and temperature rise across heater is studied and compared with experimental data for validation. Further, the code is applied to obtain the flow initiation transients of various configurations of the NCL.

Investigation on Heat Transfer Behaviour of Molten Salt Natural Circulation Loop using Numerical Simulations

Molten salts are used as a coolant/heat transfer fluid in various high temperature engineering systems owing to their high boiling point at low pressure. Natural circulation of molten salt is being preferred in some systems like solar thermal power plant or in some nuclear reactors. Such systems can be studied with the help of a natural circulation loop. In this work, heat transfer characteristics of Molten Salt Natural Circulation Loop (MSNCL) are studied using 3D CFD simulations. Molten Nitrate salt, NaNO3+KNO3 (60:40 ratio by weight), is used as a fluid in MSNCL. In the MSNCL, in heater section, flow is developing and also mixed convection flow regime exists. The local Nusselt number variation in heater is calculated from computed data and is compared with that from Boelter correlation. Steady state heat transfer characteristics are obtained over a wide range of Reynolds number using CFD simulations. Unsteady heat transfer characteristics in the oscillatory flow formed in MSNCL with horizontal heater configuration are also studied and are found to be different as compared to vertical heater placed in vertical heater horizontal cooler configuration.

Effect of Inlet Configuration on Moderator Velocity and Temperature Distribution Inside the Calandria of a Heavy Water Reactor

Computational study of the moderator flow in calandria vessel of a heavy water reactor is carried out for three different inlet nozzle configurations. For the computations, PHOENICS CFD code is used. The flow and temperature distribution for all the configurations are determined. The impact of moderator inlet jets on adjacent calandria tubes is studied. Based on these studies, it is found that the inlet nozzles can be designed in such a way that it can keep the impact velocity on calandria tubes within limit while keeping maximum moderator temperature well below its boiling limit.Copyright