Analysis of more efficient and sustainable future district heating networks

In this paper use of plate heat exchanger in the municipal district heating for the development of more sustainable hot water supply systems is analysed. To reduce the cost of coolant and the cost of its transportation a two-stage mixed scheme has been proposed, allowing the use of warm return water heating system to preheat the cold water source. Moreover, to make solution more sustainable, effective selection of heat exchanger in the same scheme could utilize low temperature sources such as geothermal, solar or waste heat. Two-stage hot water circuits are more expensive and its value relative to the parallel circuit is 2-2.5 times higher, depending on the ratio of heating and hot water loads. Application of two-stage scheme allows for the same load of hot water to save up to 30% of the carrier relative to its consumption for the conventional parallel scheme. So the benefits from getting higher efficiencies and lower operation costs must be weighed against the higher costs of installations. Effectiveness and reliability of the proposing method is demonstrated on the real heat point calculation while the possibilities for installation in combination with renewable low heat sources are analysed for Ukraine, Croatia and Hungary. The sustainability of solution is reflected trough economical, environmental and evaluation of security of supply.