Energy saving of optimum insulation thickness according to heating degree-days in pipe insulation applications

Nowadays, due to limited energy resources, rapid energy consumption and environmental impacts arising from the use of fossil resources, thermal insulation is the topic of great interest and importance to many countries and thermal engineers. In particular, the complicated and costly piping and insulation applications are considered in buildings, mechanical installations and industry.On the one hand, insulation is designed to be the best way to reduce the energy consumed in the buildings, mechanical installations and industrial systems. On the other hand, it plays an important role in the reduction of energy consumption (heat loss)regarding transmitting portion of heating and cooling loads in the buildings, mechanical installations and industrial systems. When viewed from this perspective, itcan be seen as one of the most important ways to achieve, energy efficiency and environmental sustainability of the modern cities and systems.This study aims at optimizing the insulation thickness in thepipes for different materialtypes of pipe. The discussed pipes consist of steel, plastic and copper materials. As case study, when some fuel types (coal, natural gas and fuel oil) and various insulation materials (rock wool, EPS and XPS) under theAfyonkarahisar (Turkey) climatic conditions are used, evaluation of the annual total cost, energy saving and payback period associated with insulation applications in pipes with different diameters were performed. The life-cycle cost analysis based on the degree-days (1000, 3000, 5000 and 7000 °C-days) for the optimization process was used.Firstly, the results showed that the most saving fuel type and insulation material was found as coal and XPS, respectively. The insulation priorities of the pipe material types are listed as steel and plastic materials. For reasons of their low thermal conductivity of plastic pipes, the method of this study is not a suitable method for determining the optimum thickness. Considering all the variable parameters in the analysis method, the optimum insulation thickness for steel pipe varies between 5 and 16 cm. Thus, a constant thickness of insulation can be used in large diameter steel pipe. As a result, the optimum thickness value for all pipe diameters increases with increase heating degree-days.