Design methodology for combined production and distribution for domestic hot water and space heating

Abstract

As local heat demand is reducing due to an increased insulation rate, investing in sustainable heat production becomes less interesting. Nevertheless a substantial demand of heat remains in which the thermal energy needed for the generation of domestic hot water grows relatively in importance. In the last two years standards to size production and distribution systems were revised and methods based on tap patterns were elaborated. Nevertheless, some aspects were not covered yet, e.g. how to deal with decentralized storage and how to use these results and new insights in combined heating systems, taking into account that modifications in standards for both space heating and domestic hot water installations are reducing the oversizing. In this paper, first some critical points of attention due to this evolution are illustrated with a case example. Next it is shown how different rules of thumb often developed by different manufacturers deal with these aspects, but lacking however compatibility with existing standards and/or new insights. Finally, a methodology is proposed and illustrated how to size distribution and production systems for combined heating systems taking into account central and decentralized storage and different kind of end users. The method can be used to size heating systems in collective housing or in district heating networks.

Grouped Charging of Decentralised Storage to Efficiently Control Collective Heating Systems: Limitations and Opportunities

“…In [32], it was found that the locations of the temperature sensors had a larger influence on lowering the return temperature than controlling the charging flow rate ( ṁch ). Nonetheless, a lower ṁch reduced the return temperature by 5 to 8 • C. In [33], the control strategy of [32] was further optimised to lower the peak demand in the DH and lower the return temperatures by up to 16.4 • C. Additionally, other researchers stated that the design has a major impact on energy performances [34,35]. Lyu et al [36] stated that the size of the central storage tank has a large influence on the efficiency of the central HP.…”

“…To size the central energy system, the new sizing method for CHDCs [53] was used, which was recently validated in [54]. The sizing method gives all possible combinations of thermal power in kW and "active" storage capacity in kWh to meet the peak heat demand.…”