Development of an efficient water-heating waste heat boiler

Introduction. Problems of waste gas heat recovery are relevant in the course production activities. Secondary thermal ener­gy resources are the most widely spread type of energy waste. Efficient recovery of waste heat will reduce energy costs. The building of a cafeteria, that has a water-heating waste heat boiler (WHB) represents a widely spread type of industrial buildings in eastern countries, where hot water and heating can be provided by using heat waste recovered from groups of tandoor furnaces. The purpose of the research is to study unsteady convective flows of heat passing through the pipe of a tandoor heat exchanger and to develop a simple design of a small-sized, easy to manufacture, economical and safe model of a water heating device for the needs of the national economy. Materials and methods. The research is based on a comprehensive methodology employed to study, analyze and gene­ralize thermophysical processes based on the study of convective unsteady heat flows in heat exchanger pipes of tandoor furnaces. Results. The research result represents higher thermal efficiency of the WHB installed in the building of a cafeteria due to the heating, accumulation and heat transfer by vertical finned steel heat-exchanger pipes in the cylindrical boiler in the course of convective heating by the outlet gas used as the heat carrier without returning heat to the water heating boiler. Conclusions. The cafeteria building has scientifically and practically grounded design of a WHB tandoor group, which is a vertical cylindrical tank filled with water, in which vertical outlet heat exchange pipes are placed. Heat, emitted during the operation of tandoors, is used to bake flatbreads and bread by burning wood, coal, natural gas or electric heaters. This heat heats boiler sections to supply hot water to consumers and heat the building premises. The method of finned pipes extends the field of application of the device, increasing the coefficient of heat capacity and heat exchange, as well as the capacity of equipment.