CFD Analysis on Waste Heat Recovery Unit for Boiler Plant

A waste heat recovery unit (WHRU) is an energy recovery heat exchanger that recovers heat from hot streams with high energy contents. In this study, the modification of the design of the waste heat recovery unit which receives flue gases from the boiler in order extract the heat from flue gases and enhance the heat transfer rate. Generally, the body of the waste heat recovery unit of the boiler is made up of Aluminium which receives exhaust gases from the boiler plant through two inlets of different sizes which connected to exhaust outlets of the plant. This unit assists to extract the heat from the flue gases with help of rubber jacket wrapped around it which has inlet and outlet for circulation of water in order to extract the heat from the flue gases. Due to wear and tear of the rubber jacket which leads leakage of the water and steam, leads to poor exchange of heat and hence needs frequent replacement instead of service. To overcome the problems of rubber jacket life, an attempt is made by replacing the rubber jacket with coiled pipes on both the ducts of the unit, further by increasing the rigidity of the body with improved thickness in order to have reduced vibrations. Using CFD analysis the velocity streamlines before and after modification of the design are compared and hear transfer rates are evaluated for analysis using Duct temperature contours for both counter and parallel flow approaches.