Life Cycle Assessment of Dispersed Phase Change Material Heat Accumulators for Cooperation with Buildings in the District Heating System

Abstract

The wide use of energy-efficient district heating systems allows for decreased atmospheric pollution resulting from lower emissions. One of the ways to increase the efficiency of existing district heating systems, and a key element of new systems using renewable energy sources, is modern heat storage technology—the utilization of dispersed PCM heat accumulators. However, the use of different solutions and the inconsistency of selection methods make it difficult to compare the obtained results. Therefore, in this paper, using TRNSYS software, a standardization of the selection of dispersed PCM heat accumulators for cooperation with buildings in the DHS was proposed along with a Life Cycle Assessment. Life Cycle Assessment could be a good, versatile indicator for new developments in district heating systems. A new contribution to the research topic was the Life Cycle Assessment itself as well as the range of heat output of the substations up to 2000 kW and the development of nomograms and unitary values for the selection of individual parameters based on the relative amount of heat uncollected by buildings. The technical potential of heat storage value, %ΔQi,st, was from 49.4% to 59.6% of the theoretical potential of heat storage. The increases in the active volume of the PCM heat accumulator, dVPCM, and the mass of the required amount of PCM, dmst, were, respectively, 0.8 × 10−2–4.0 m3/kW and 1.3–6.7 × 10−2 kg/kW. Due to dispersed heat storage, an increase in system efficiency of 41% was achieved. LCA analysis showed that a positive impact on the environment was achieved, expressed as negative values of the Eco-indicator from −0.504 × 10−2 to −6.44 × 10−2 kPt/kW.