Analysis of “Conti” pre-insulated pipes with diffusion barrier versus traditional pre-insulated pipes used in district heating networks

Pre-insulated pipes have reduced heat losses, compared to those that are insulated on the field by using different materials, such as mineral wool. The advantages are offered mainly by the polyurethane foam, which has low thermal conductivity rates. This material is not the only source of energy savings. Companies keep trying to develop more and more energy efficient solutions, by innovative production methods. This paper presents technical and economical comparative information on pre-insulated pipes realized in the traditional way (discontinuous production method) and a new method based on continuous foaming, which is used in production of “Conti” pipes. Analysis of heat losses is made for a real dimensioned district heating network in two cases: case study 1 that focuses on pipes produced through the discontinuous method and case study 2 that focuses on pipes produced through the continuous method. According to LOGSTOR experiments, the ageing process increases the thermal conductivity rates of traditional pre-insulated pipes, while “Conti” pipes maintain the initial rates during the entire lifetime. Results underline that in the studied situation, heat losses are reduced by 20.9% when “Conti” pipes are used instead of traditional pre-insulated pipes. Concluding, investments in “Conti” pipes have less than 10 years payback period, which fully recommends the new production method.